Step-down power supply circuit

Abstract

To suppress a drop in an output voltage of a step-down power supply circuit when the load increases.SOLUTION: A step-down power supply circuit includes at least a first inductor (L1), a second inductor (L2), a first LS switch (SL1), a second LS switch (SL2), a first HS switch (SH1), a flying capacitor (CFLY1), a second HS switch (SH2), an output voltage drop suppression capacitor (CA), and an output voltage drop suppression switch (SA). A current flows through the load by switching between a first phase, a second phase, and a third phase during the steady operation of the step-down power supply circuit in which SA is turned off. When the load of the step-down power supply circuit increases, which is when the current flowing through the load increases as the resistance of the load decreases, SA is turned off, and a current flows from an input DC power supply to the load through at least SH1, CFLY1, and L2, while the charge stored in CA during steady operation of the step-down power supply circuit flows to the load through at least SA and L1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a step-down power supply circuit. [Background technology]

[0002] Recently, switched capacitor (SC) power supplies have been attracting attention due to their high step-down voltage and capacitance. There are various types of SC circuits, such as series-parallel, ladder (Cockcroft-Walton), Dickson, and Fibonacci types. In any SC circuit, a single inductor may charge or discharge two or more flying capacitors in parallel. In this case, the imbalance is eliminated by charge redistribution (hard charging) via a switch at the start of each phase, but this results in losses due to hard charging.

[0003] As a method for avoiding such hard charging and further improving the step-down ratio, a dual-inductor hybrid Dickson converter with two inductors L1 and L2 has been proposed (see Non-Patent Documents 1 and 2). In a dual-inductor hybrid Dickson converter, the current flowing through each flying capacitor is matched to the current through the inductor to prevent hard charging, while the output voltage is kept at DV IN / (2N), which doubles the step-down ratio compared to a single inductor. In addition, because the load current can be divided between the two inductors L1 and L2, it is possible to increase the load current without increasing the inductor size. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Ratul Das, Gab-Su Seo and Hanh-Phuc Le “A 120V-to-1.8V 91.5%-Efficient 36-W Dual-Inductor Hybrid Converter with Natural Soft-charging Operations for Direct Extreme Conversion Ratios” 2018 IEEE Energy Conversion Congress and Exposition (ECCE) [Non-patent document 2] Tianshi Xie, Ratul Das, Gab-Su Seo, Dragan Maksimovic and Hanh-Phuc Le “Multiphase Control for Robust and Complete Soft-charging Operation of Dual Inductor Hybrid Converter” 2019 IEEE Applied Power Electronics Conference and Exposition (APEC) Summary of the Invention [Problem to be solved by the invention]

[0005] Although the dual inductor hybrid Dickson converter has these excellent features, there is a problem when it comes to load response. LOAD When suddenly increased, the inductor current I flowing through inductors L1 and L2 L1 , I L2 is the increased output load I LOAD Half of (I LOAD / 2) for each inductor current I L1 , I L2 is the switching node V X1 , V X2(the connection point of inductors L1 and L2) is at a high level (when the inductor is charging). However, this dual-inductor hybrid Dickson converter uses both switching nodes V X1 , V X2 Since it is not permitted for both of these to be at a high level, the control circuit X1 , V X2 Therefore, both inductor currents I L1 , I L2 cannot increase simultaneously, and the output load I LOAD Half of (I LOAD / 2), during which time the output smoothing capacitor C OUT Charge continues to be supplied to the load from OUT temporarily drops significantly below the target voltage.

[0006] In view of the above-mentioned problems, the present invention provides a method for reducing the voltage V at the connection point between the first inductor L1 and the second inductor L2 and the load when the load increases. OUT It is an object of the present invention to provide a step-down power supply circuit capable of suppressing a decrease in power consumption. [Means for solving the problem]

[0007] One aspect of the present invention is a step-down power supply circuit including at least a first inductor connected to a load, a second inductor connected to the load in parallel with the first inductor, a first low-side switch, a second low-side switch, a first high-side switch connected to an input DC power supply, a first flying capacitor connected to the first high-side switch, a second high-side switch connected to the first high-side switch in parallel with the first flying capacitor, an output voltage drop suppression capacitor connected in parallel to the first high-side switch, and an output voltage drop suppression switch connected in series to the output voltage drop suppression capacitor, wherein one end of the first inductor and one end of the second inductor are connected to the load, the other end of the first inductor is connected to one end of the first low-side switch, the other end of the first low-side switch is connected to ground, the other end of the second inductor is connected to one end of the second low-side switch, the other end of the second low-side switch is connected to the ground, and the output voltage drop suppression switch During steady operation of the step-down power supply circuit, when the switch is in an off state, at least a first phase in which a current flows from the input DC power supply to the load via at least the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the ground to the load via the first low-side switch and the first inductor, a second phase in which a current flows from the ground to the load via the second low-side switch and the second inductor, and a current flows from the ground to the load via the first low-side switch and the first inductor, and a third phase in which a current flows from the ground to the load via the second low-side switch and the second inductor, and a current flows from the first flying capacitor to the load via at least the second high-side switch and the first inductor, is switched, whereby a current of a first magnitude flows to the load, and the current flowing to the load increases as the resistance of the load decreases, and the output voltage drop suppression switch is turned on;A fourth phase is entered in which a current flows from the input DC power supply to the load via at least the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the input DC power supply to the load via at least the output voltage drop suppression capacitor, the output voltage drop suppression switch, and the first inductor, and a current of a second magnitude larger than the first magnitude flows through the load.

[0008] In one aspect of the step-down power supply circuit of the present invention, one end of the output voltage drop suppression capacitor is connected to the input DC power supply, the other end of the output voltage drop suppression capacitor is connected to one end of the output voltage drop suppression switch, and the other end of the output voltage drop suppression switch is connected to the other end of the first inductor, and in the fourth phase, the output voltage drop suppression switch and the first high-side switch are turned on, and the second high-side switch, the first low-side switch, and the second low-side switch are turned off, so that a current flows from the input DC power supply to the load via the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the input DC power supply to the load via the output voltage drop suppression capacitor, the output voltage drop suppression switch, and the first inductor.

[0009] A step-down power supply circuit according to one aspect of the present invention may include a second output voltage drop suppression capacitor, one end of which is connected to the input DC power supply, the other end of which is connected to one end of the output voltage drop suppression switch, the other end of which is connected to one end of the second output voltage drop suppression capacitor, and the other end of the second output voltage drop suppression capacitor is connected to the other end of the first inductor, and in the fourth phase, the output voltage drop suppression switch and the first high-side switch are turned on, and the second high-side switch, the first low-side switch, and the second low-side switch are turned off, thereby causing a current to flow from the input DC power supply to the load via the first high-side switch, the first flying capacitor, and the second inductor, and also causing a current to flow from the input DC power supply to the load via the output voltage drop suppression capacitor, the output voltage drop suppression switch, the second output voltage drop suppression capacitor, and the first inductor. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a step-down power supply circuit that can suppress a drop in voltage at the connection point between the load and the first inductor and the second inductor when the load increases. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of a circuit in which the step-down power supply circuit 1 of the first embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 2] 2 is a diagram for explaining phases of the step-down power supply circuit 1 of the first embodiment. FIG. [Figure 3] 2 is a diagram for explaining phases of the step-down power supply circuit 1 of the first embodiment. FIG. [Figure 4] 3 is a waveform diagram showing an example of an operating waveform in a steady state of the step-down power supply circuit 1 of the first embodiment. FIG. [Figure 5]3 is a waveform diagram showing an example of an operating waveform when the load of the step-down power supply circuit 1 of the first embodiment suddenly increases. FIG. [Figure 6] 1 is a diagram showing a circuit in which a step-down power supply circuit of a comparative example is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 7] 10 is a waveform diagram showing the operating waveforms of the step-down power supply circuit of the comparative example when the load suddenly increases; [Figure 8] FIG. 10 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the second embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 9] FIG. 10 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the third embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 10] FIG. 10 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the fourth embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 11] FIG. 10 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the fifth embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 12] FIG. 10 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the sixth embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 13] FIG. 13 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the eighth embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 14] FIG. 13 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the ninth embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 15] FIG. 22 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the tenth embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 16]FIG. 23 is a diagram showing a first example of a circuit in which the step-down power supply circuit 1 of the eleventh embodiment is applied to an input DC power supply VIN, a load LD, and an output smoothing capacitor COUT. [Figure 17] FIG. 1 is a diagram illustrating an outline of a simulation circuit. [Figure 18] FIG. 2 is a diagram showing an outline of the inside of a control circuit (Control). [Figure 19] FIG. 4 is a diagram showing waveforms of a control circuit. [Figure 20] FIG. 10 is a diagram showing a simulation waveform of VOUT during load fluctuation when VIN=24 V, VOUT=1 V, and the switching frequency is 2.5 MHz. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the step-down power supply circuit of the present invention will be described.

[0013] First Embodiment FIG. 1 shows a step-down power supply circuit 1 according to a first embodiment of the present invention. IN , load LD and output smoothing capacitor C OUT 2 and 3 are diagrams illustrating the phases of the step-down power supply circuit 1 of the first embodiment. In detail, FIG. 2(A) shows phase "Phase A1" of the step-down power supply circuit 1, FIG. 2(B) shows phase "Phase B" of the step-down power supply circuit 1, FIG. 3(A) shows phase "Phase A2" of the step-down power supply circuit 1, and FIG. 3(B) shows phase "Phase C" of the step-down power supply circuit 1. Fig. 4 is a waveform diagram showing an example of the operating waveforms in a steady state of the step-down power supply circuit 1 of the first embodiment. Fig. 5 is a waveform diagram showing an example of the operating waveforms of the step-down power supply circuit 1 of the first embodiment when the load suddenly increases.

[0014] In the example shown in FIGS. 1 to 5, the step-down power supply circuit 1 of the first embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1and the high-side switch S H2 and flying capacitor C FLY1 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 1) and one end of the inductor L2 (the end on the right side in FIG. 1) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 1) is connected to the low-side switch S L1 The low-side switch S L1 The other end of inductor L2 (the end on the left side of Figure 1) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 1) is grounded.

[0015] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 1) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in Figure 1) of the FLY1 (the upper end in Figure 1) and the high-side switch S H2 In other words, the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end of the high-side switch S (the lower end in FIG. 1) is connected to the other end of the inductor L2 (the left end in FIG. 1).H2 The other end (the end on the lower side in FIG. 1) is connected to the other end (the end on the right side in FIG. 1) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 1) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in Figure 1) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 1). A The other end (the end on the lower side in FIG. 1) is connected to the other end (the end on the right side in FIG. 1) of the inductor L1.

[0016] The steady-state operation of the step-down power supply circuit 1 of the first embodiment includes a phase "Phase A1" shown in Figures 2(A) and 4, a phase "Phase B" shown in Figures 2(B) and 4, and a phase "Phase A2" shown in Figures 3(A) and 4. During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, as shown in Figures 4 and 5, phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order of "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... As shown in Figure 2(A), in phase "PhaseA1", the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor CFLY1 In detail, as shown in FIG. 4, a current I flows through the inductor L2. L2 Also, as shown by the arrow on the left side of Figure 2(A), the low-side switch S L1 In other words, as shown in FIG. 4, the current I L1 In phase "Phase A1", the flying capacitor C FLY1 and inductor L2 enter a state of storing energy, and inductor L1 enters a state of releasing energy. The current I shown in Figure 4 LOAD / 2 is the current I flowing through inductor L1 L1 and the current I flowing through inductor L2 L2 and the average current I flowing through the load LD. LOAD This is equivalent to half of the total. In detail, as shown in Figure 4, in phase "PhaseA1", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 In addition, the flying capacitor C FLY1 Voltage V CFLY1 increases.

[0017] As shown in Figure 2(B), in phase "Phase B", the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 and high-side switch S H2 As a result, the low-side switch S L2 In other words, as shown in FIG. 4, the current I L2Also, as shown by the arrow on the left side of Figure 2(B), the low-side switch S L1 In other words, as shown in FIG. 4, the current I L1 In phase "Phase B," inductor L1 and inductor L2 enter a state in which they release energy. In detail, as shown in Figure 4, in phase "Phase B", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 Also, the flying capacitor C FLY1 Voltage V CFLY1 becomes high.

[0018] As shown in Figure 3(A), in phase "PhaseA2", the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 and the low-side switch S L1 As a result, the low-side switch S L2 In other words, as shown in FIG. 4, the current I L2 Also, as shown by the arrow on the left side of Figure 3(A), the flying capacitor C FLY1 From the high-side switch S H2 In detail, as shown in FIG. 4, a current I flows through the inductor L1. L1 In phase "PhaseA2", the flying capacitor C FLY1 Inductor L1 and inductor L2 enter a state of discharging energy, and inductor L1 enters a state of storing energy. In detail, as shown in Figure 4, in phase "PhaseA2", the low-side switch SL1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 Also, the flying capacitor C FLY1 Voltage V CFLY1 decreases. In the phase "Phase B" that is executed after the phase "Phase A2", the flying capacitor C FLY1 Voltage V CFLY1 becomes low. As shown in Figure 5, in the period before the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start of phase "Phase C"), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0019] The current I that flows through the load LD as the resistance of the load LD decreases LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" is interrupted and executed (started) when the current I LOAD The increase in, for example, the inductor current I L1 , inductor current I L2 , or the voltage V at the connection point between inductor L1 and inductor L2 and load LD OUT Figure 5 shows that the load on the step-down power supply circuit 1 increases during phase "PhaseA1" and S A This is an example where the output voltage drop suppression switch S A The time when the current I flows through the load LD decreases as the resistance of the load LD decreases, is not limited to the time when the current I flows through the load LD, for example, in the other phases, such as the phases "Phase B" and "Phase A2". LOAD may increase, and in that case, the output voltage drop suppression switch SA is turned on and the operation of phase "Phase C" is interrupted and executed. As shown in FIG. 3(B), in phase “Phase C” (i.e., while the operation of phase “Phase C” is being performed), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows to the load LD via the inductor L1 and the inductor L2. That is, as shown in FIG. 5, the current I L2 Also, as shown by the arrow on the left side of Figure 3(B), the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows to the load LD via the inductor L1 and the inductor L2. That is, as shown in FIG. L1 In Phase C, the flying capacitor C FLY1 and inductor L2 are in a state of storing energy, and the output voltage drop suppression capacitor C A and inductor L1 are in a state of storing energy. In detail, as shown in Figure 5, in phase "Phase C", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. As shown in Figure 5, from the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start of phase "Phase C"), the current I LOADbecomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value). The monitored inductor current I L1 , inductor current I L2 , or voltage V OUT When the output voltage drop suppression switch S A is turned off, the operation of phase "Phase C" ends, and the step-down power supply circuit 1 enters a steady state operation (steady operation).

[0020] Figure 6 shows the comparison example of a step-down power supply circuit with an input DC power supply V IN , load LD and output smoothing capacitor C OUT 7 is a waveform diagram showing the operating waveforms of the step-down power supply circuit of the comparative example when the load suddenly increases. The step-down power supply circuit of the comparative example shown in FIG. 6 includes the output voltage drop suppression capacitor C A and output voltage drop suppression switch S A There is no provision for this. As shown in FIG. 7, in the phase “Phase A1” of the step-down power supply circuit of the comparative example, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 and the low-side switch S L2 As a result, the current I flowing through the inductor L2 becomes equal to the phase "Phase A1" of the step-down power supply circuit 1 of the first embodiment shown in FIG. L2 increases, and the current I L1 decreases, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. As shown in FIG. 7, in the phase “Phase B” of the step-down power supply circuit of the comparative example, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 and high-side switch S H2 As a result, the current I flowing through the inductor L2 becomes equal to the phase "Phase B" of the step-down power supply circuit 1 of the first embodiment shown in FIG. L2 decreases, and the current I L1 decreases, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0021] As shown in FIG. 7, in the phase “Phase A2” of the step-down power supply circuit of the comparative example, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 and the low-side switch S L1 As a result, the current I flowing through the inductor L2 becomes equal to the phase "Phase A2" of the step-down power supply circuit 1 of the first embodiment shown in FIG. L2 decreases, and the current I L1 increases, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the comparative example of the step-down power supply circuit, the current I that flows through the load LD as the resistance of the load LD decreases LOADWhen the voltage Vcc increases, one of the phases "Phase A1", "Phase B" and "Phase A2" is executed in a preset order, without the operation of phase "Phase C" being executed as an interruption, as in the step-down power supply circuit 1 of the first embodiment. As shown in the example in Figure 7, during the execution of phase "PhaseA1", the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When increases, the current I L1 decreases, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, the current I L1 and the current I flowing through inductor L2 L2 The sum of these is the current I LOAD The voltage V at the connection point between inductor L1 and inductor L2 and load LD becomes smaller than the value of / 2. OUT will decrease significantly. In phase "PhaseA2" executed after phase "PhaseA1", the current I L2 decreases, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 is low, the current I L1 and the current I flowing through inductor L2 L2 The sum of these is still the current I LOAD The voltage V at the connection point between inductor L1 and inductor L2 and load LD becomes smaller than the value of / 2. OUT The decline will continue.

[0022] In contrast, in the step-down power supply circuit 1 of the first embodiment, as described above, the current I LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A In phase "Phase C", the operation of the input DC power supply V IN From the high-side switch SH1 and flying capacitor C FLY1 A current flows to the load LD via the inductor L2 and the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L2 and the load LD via the inductor L1. L2 As the current I flows through the inductor L1, L1 increases. Therefore, in the step-down power supply circuit 1 of the first embodiment, the voltage V at the connection point between the inductor L1 and the load LD and the inductor L2 when the load increases is smaller than that in the step-down power supply circuits of the comparative examples shown in FIGS. 6 and 7. OUT The decrease in the amount of In the example shown in Figure 1, the output voltage drop suppression capacitor C A One end of the (upper end in Figure 1) is connected to the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in Figure 1) of the output voltage drop suppression switch S A ) (the upper end of Figure 1), and the output voltage drop suppression switch S A The other end (the end on the lower side in FIG. 1) of the output voltage drop suppression switch S A One end of the input DC power supply V IN The output voltage drop suppression switch S A The other end of the output voltage drop suppression capacitor C A The output voltage drop suppression capacitor C A The other end of the output voltage drop suppression switch S A and output voltage drop suppression capacitor C A and may be connected in series.

[0023] The steady operation of the step-down power supply circuit 1 of the first embodiment shown in Figures 1 to 5 is similar to the steady operation of the step-down power supply circuit of the comparative example shown in Figures 6 and 7. During the steady operation of the step-down power supply circuit 1 of the first embodiment, the output voltage drop suppression switch S A In principle, there is no need to turn on the output voltage drop suppression capacitor C A When adjusting the voltage applied to the output, the output voltage drop suppression switch S A It is possible that the

[0024] As described above, in the step-down power supply circuit 1 of the first embodiment shown in FIGS. 1 to 5, the current I LOAD When the current I flows through the inductor L1, the operation of phase C is interrupted and executed. L1 and the current I flowing through inductor L2 L2 As a result, the current I flowing through the inductor L1 L1 and the current I flowing through inductor L2 L2 The sum of these is the current I flowing through the load LD. LOAD The time required for the voltage to follow the current I can be made shorter than that of the comparative step-down power supply circuits shown in FIGS. 6 and 7. LOAD When the voltage V OUT The decrease in the output voltage can be suppressed more effectively than in the comparative step-down power supply circuits shown in FIGS.

[0025] In the step-down power supply circuit 1 of the first embodiment shown in FIGS. 1 to 5, the current I LOAD When the current I flows through the inductor L1, for example, the operation of phase "Phase B" can be interrupted (the operation period of phase "Phase B" can be extended longer than usual) to reduce the current I L1 and the current I flowing through inductor L2 L2 The sum of these is the current I flowing through the load LD. LOAD This allows the company to quickly follow suit.

[0026] In another example, the output voltage drop suppression capacitor C A However, the high-side switch SH1 and high-side switch S H2 The capacitor may also function as a bootstrap capacitor for a driver (not shown) that drives the transistor.

[0027] Second Embodiment A second embodiment of the step-down power supply circuit of the present invention will now be described. Except for the points described below, the step-down power supply circuit 1 of the second embodiment is configured similarly to the step-down power supply circuit 1 of the first embodiment described above. Therefore, the step-down power supply circuit 1 of the second embodiment can achieve the same effects as the step-down power supply circuit 1 of the first embodiment described above, except for the points described below.

[0028] FIG. 8 shows the step-down power supply circuit 1 of the second embodiment. IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0029] In the example shown in FIG. 8, the step-down power supply circuit 1 of the second embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and flying capacitor C FLY1 and a flying capacitor C that functions as a second output voltage drop suppression capacitor. FLY2 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A As shown in this example, the flying capacitor used in the step-down power supply circuit can also function as the second capacitor for suppressing a drop in output voltage, which has the advantage of reducing the number of capacitor components. The same applies to other embodiments (embodiments corresponding to FIGS. 10, 12, 13, and 15) described later. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor COUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 8) and one end of the inductor L2 (the end on the right side in FIG. 8) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 8) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 8) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 8) is grounded.

[0030] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 8) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 8) of the FLY1 (the upper end in Figure 8) and the high-side switch S H2 8. That is, the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the lower end in FIG. 8) of the high-side switch S is connected to the other end (the left end in FIG. 8) of the inductor L2. H2 The other end of the MOSFET (the lower end in Figure 8) is connected to the high-side switch S H3 (the upper end of Figure 8) and the flying capacitor C FLY2 The high-side switch S H3The other end of the flying capacitor C (the lower end in FIG. 8) is connected to the other end of the inductor L2 (the left end in FIG. 8). FLY2 The other end (the end on the lower side in FIG. 8) of the (second output voltage drop suppression capacitor) is connected to the other end (the end on the right side in FIG. 8) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 8) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 8) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end (the upper end in FIG. 8) of the A The other end of the MOSFET (the lower end in Figure 8) is connected to the high-side switch S H3 (the upper end of Figure 8) and the flying capacitor C FLY2 8. The second output voltage drop suppression capacitor is connected to one end (the upper end in FIG. 8) of the second output voltage drop suppression capacitor.

[0031] 8, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", and a phase "Phase A3" to be described later. During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", and "PhaseA3" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 8, the high-side switch S H1 and the low-side switch SL1 is turned on, and the high-side switch S H2 , high-side switch S H3 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 8, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0032] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 8, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 and high-side switch S H3 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in phase "Phase B" of the step-down power supply circuit 1 shown in Figure 8, the low-side switch S L1 and the voltage V at the connection point with inductor L1X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0033] In phase A2 of the step-down power supply circuit 1 shown in Figure 8, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A2" of the step-down power supply circuit 1 shown in FIG. 8, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0034] In phase A3 of the step-down power supply circuit 1 shown in Figure 8, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A3" of the step-down power supply circuit 1 shown in FIG. 8, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 8, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0035] In the example shown in Figure 8, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 8 (i.e., during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 8, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 8, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0036] The step-down power supply circuit 1 of the second embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the step-down power supply circuit 1 of the second embodiment is shown in FIG. 8, in which the step-down power supply circuit 1 of the second embodiment is connected to an input DC power supply V IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0037] In the second example of the step-down power supply circuit 1 of the second embodiment, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S ADuring steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the second embodiment, the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H2 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the second embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0038] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the second embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2and high-side switch S H3 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the second embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0039] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the second embodiment, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, similar to the example shown in Figure 8, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2X2 becomes low. In the second example of the step-down power supply circuit 1 of the second embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0040] In the second example of the step-down power supply circuit 1 of the second embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the second embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the second embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the second embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0041] Third Embodiment A third embodiment of the step-down power supply circuit of the present invention will now be described. Except for the points described below, the step-down power supply circuit 1 of the third embodiment is configured similarly to the step-down power supply circuit 1 of the first embodiment described above. Therefore, the step-down power supply circuit 1 of the third embodiment can achieve the same effects as the step-down power supply circuit 1 of the first embodiment described above, except for the points described below.

[0042] FIG. 9 shows a step-down power supply circuit 1 according to the third embodiment, in which an input DC power supply V IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0043] In the example shown in FIG. 9, the step-down power supply circuit 1 of the third embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and flying capacitor C FLY1 and flying capacitor C FLY2 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S AIt is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 9) and one end of the inductor L2 (the end on the right side in FIG. 9) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 9) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 9) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 9) is grounded.

[0044] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 9) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 9) of the FLY1 (the upper end in Figure 9) and the high-side switch S H2 9. That is, the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the lower end in FIG. 9) of the high-side switch S is connected to the other end (the left end in FIG. 9) of the inductor L2. H2 The other end (the lower end in Figure 9) of the H3 One end of the (upper end of Figure 9) and the flying capacitor C FLY2The high-side switch S H3 The other end of the flying capacitor C (the end on the bottom side in FIG. 9) is connected to the other end of the inductor L2 (the end on the left side in FIG. 9). FLY2 The other end (the end on the lower side in FIG. 9) is connected to the other end (the end on the right side in FIG. 9) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 9) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 9) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 9). A The other end (the end on the lower side in FIG. 9) is connected to the other end (the end on the right side in FIG. 9) of the inductor L1.

[0045] 9, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", and a phase "Phase A3". During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", and "PhaseA3" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 9, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2, high-side switch S H3 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 9, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0046] In phase B of the step-down power supply circuit 1 shown in Figure 9, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 and high-side switch S H3 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 9, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2and the voltage V at the connection point with inductor L2 X2 becomes low.

[0047] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 9, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0048] In phase A3 of the step-down power supply circuit 1 shown in Figure 9, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in phase "PhaseA3", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 9, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0049] In the example shown in Figure 9, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 9 (i.e., during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch SA A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 9, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 9, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0050] The step-down power supply circuit 1 of the third embodiment is an input DC power supply V IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the step-down power supply circuit 1 of the third embodiment is shown in FIG. 9, in which the step-down power supply circuit 1 of the third embodiment is connected to an input DC power supply V IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0051] In the second example of the step-down power supply circuit 1 of the third embodiment, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the third embodiment, the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H2 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the third embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0052] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the third embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 and high-side switch S H3 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch SL1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the third embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0053] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the third embodiment, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the third embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current ILOAD / 2 is also a relatively small value).

[0054] In the second example of the step-down power supply circuit 1 of the third embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the third embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the third embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the third embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0055] <Fourth embodiment> A fourth embodiment of the step-down power supply circuit of the present invention will now be described. Except for the points described below, the step-down power supply circuit 1 of the fourth embodiment is configured similarly to the step-down power supply circuit 1 of the second embodiment described above. Therefore, the step-down power supply circuit 1 of the fourth embodiment can achieve the same effects as the step-down power supply circuit 1 of the second embodiment described above, except for the points described below.

[0056] FIG. 10 shows a step-down power supply circuit 1 according to the fourth embodiment. IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0057] In the example shown in FIG. 10, the step-down power supply circuit 1 of the fourth embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4 and flying capacitor C FLY1 and a flying capacitor C that functions as a second output voltage drop suppression capacitor. FLY2 and flying capacitor C FLY3 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUTare connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 10) and one end of the inductor L2 (the end on the right side in FIG. 10) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 10) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 10) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 10) is grounded.

[0058] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 10) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 10) of the FLY1 (the upper end in Figure 10) and the high-side switch S H2 10) is connected to one end of the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the end on the lower side in FIG. 10) of the high-side switch S is connected to the other end (the end on the left side in FIG. 10) of the inductor L2. H2 The other end of the high-side switch S H3 (the upper end of Figure 10) and the flying capacitor C FLY2 The high-side switch S H3 The other end (the lower end in FIG. 10) of the FLY3(the upper end in Figure 10) and the high-side switch S H4 The flying capacitor C is connected to one end of the FLY3 The other end (the end on the lower side in FIG. 10) of the high-side switch S is connected to the other end (the end on the left side in FIG. 10) of the inductor L2. H4 The other end of the flying capacitor C (the lower end in FIG. 10) is connected to the other end of the inductor L1 (the right end in FIG. 10). FLY2 The other end (the end on the lower side in FIG. 10) of the (second output voltage drop suppression capacitor) is connected to the other end (the end on the right side in FIG. 10) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 10) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 10) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 10). A The other end of the high-side switch S H3 (the upper end of Figure 10) and the flying capacitor C FLY2 10) (the second output voltage drop suppression capacitor).

[0059] 10, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", and a phase "Phase A4" to be described later. During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S ADuring steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", and "PhaseA4" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 10, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 10, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0060] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 10, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch SH3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 10, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0061] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 10, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A2" of the step-down power supply circuit 1 shown in FIG. 10, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch SL2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0062] In phase A3 of the step-down power supply circuit 1 shown in Figure 10, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A3" of the step-down power supply circuit 1 shown in FIG. 10, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0063] In phase A4 of the step-down power supply circuit 1 shown in Figure 10, the high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A4" of the step-down power supply circuit 1 shown in FIG. 10, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the example shown in FIG. 10, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0064] In the example shown in Figure 10, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 10 (i.e., during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 10, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 10, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0065] The step-down power supply circuit 1 of the fourth embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the fourth embodiment (the second example of the step-down power supply circuit 1 of the fourth embodiment) is a step-down power supply circuit 1 of the fourth embodiment shown in FIG. IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0066] In the second example of the step-down power supply circuit 1 of the fourth embodiment, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch SA During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0067] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the low-side switch S L1 and the low-side switch S L2is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0068] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the fourth embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0069] In the second example of the step-down power supply circuit 1 of the fourth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the fourth embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the fourth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the fourth embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0070] Fifth Embodiment A fifth embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the fifth embodiment is configured similarly to the step-down power supply circuit 1 of the third embodiment, except for the points described below. Therefore, the step-down power supply circuit 1 of the fifth embodiment can achieve the same effects as the step-down power supply circuit 1 of the third embodiment, except for the points described below.

[0071] FIG. 11 shows a step-down power supply circuit 1 according to the fifth embodiment, in which an input DC power supply V IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0072] In the example shown in FIG. 11, the step-down power supply circuit 1 of the fifth embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4 and flying capacitor C FLY1 and flying capacitor C FLY2 and flying capacitor C FLY3 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 11) and one end of the inductor L2 (the end on the right side in FIG. 11) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 11) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 11) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 11) is grounded.

[0073] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 11) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 11) of the FLY1 (the upper end in Figure 11) and the high-side switch S H2 11) is connected to one end of the high-side switch SH2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the end on the lower side in FIG. 11) of the high-side switch S is connected to the other end (the end on the left side in FIG. 11) of the inductor L2. H2 The other end of the high-side switch S H3 (the upper end of Figure 11) and the flying capacitor C FLY2 The high-side switch S H3 The other end (the lower end in FIG. 11) of the FLY3 (the upper end in Figure 11) and the high-side switch S H4 The flying capacitor C is connected to one end of the FLY3 The other end (the end on the lower side in FIG. 11) of the high-side switch S is connected to the other end (the end on the left side in FIG. 11) of the inductor L2. H4 The other end of the flying capacitor C (the end on the bottom side in FIG. 11) is connected to the other end of the inductor L1 (the end on the right side in FIG. 11). FLY2 The other end (the end on the lower side in FIG. 11) is connected to the other end (the end on the right side in FIG. 11) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 11) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 11) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 11). A The other end (the end on the lower side in FIG. 11) is connected to the other end (the end on the right side in FIG. 11) of the inductor L1.

[0074] 11, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", and a phase "Phase A4". During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", and "PhaseA4" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 11, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 11, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2becomes high.

[0075] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 11, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 11, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0076] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 11, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor CFLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0077] In phase A3 of the step-down power supply circuit 1 shown in Figure 11, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in phase "PhaseA3", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0078] In phase A4 of the step-down power supply circuit 1 shown in Figure 11, the high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch SH1 , high-side switch S H2 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA4", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the example shown in FIG. 11, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0079] In the example shown in Figure 11, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 11 (that is, during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch SH4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 11, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 11, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase "Phase C"). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0080] The step-down power supply circuit 1 of the fifth embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the fifth embodiment (the second example of the step-down power supply circuit 1 of the fifth embodiment) is a step-down power supply circuit 1 of the fifth embodiment shown in FIG. IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0081] In the second example of the step-down power supply circuit 1 of the fifth embodiment, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the fifth embodiment, the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the fifth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0082] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the fifth embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the fifth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0083] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the fifth embodiment, the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2and flying capacitor C FLY2 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the fifth embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0084] In the second example of the step-down power supply circuit 1 of the fifth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the fifth embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the fifth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the fifth embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0085] Sixth Embodiment A sixth embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the sixth embodiment is configured similarly to the step-down power supply circuit 1 of the fourth embodiment, except for the points described below. Therefore, the step-down power supply circuit 1 of the sixth embodiment can achieve the same effects as the step-down power supply circuit 1 of the fourth embodiment, except for the points described below.

[0086] FIG. 12 shows a step-down power supply circuit 1 according to the sixth embodiment, in which an input DC power supply V IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0087] In the example shown in FIG. 12, the step-down power supply circuit 1 of the sixth embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4 and the high-side switch S H5 and flying capacitor C FLY1 and a flying capacitor C that functions as a second output voltage drop suppression capacitor. FLY2 and flying capacitor C FLY3 and flying capacitor C FLY4 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 12) and one end of the inductor L2 (the end on the right side in FIG. 12) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 12) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 12) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 12) is grounded.

[0088] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 12) is connected to the input DC power supply V INHigh-side switch S H1 The other end (the lower end in FIG. 12) of the FLY1 (the upper end in Figure 12) and the high-side switch S H2 12) is connected to one end of the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the end on the lower side in FIG. 12) of the high-side switch S is connected to the other end (the end on the left side in FIG. 12) of the inductor L2. H2 The other end (the lower end in Figure 12) of the H3 One end of the (upper end of Figure 12) and the flying capacitor C FLY2 The high-side switch S H3 The other end (the lower end in FIG. 12) of the FLY3 (the upper end in Figure 12) and the high-side switch S H4 The flying capacitor C is connected to one end of the FLY3 The other end (the end on the lower side in FIG. 12) of the high-side switch S is connected to the other end (the end on the left side in FIG. 12) of the inductor L2. H4 The other end (the lower end in Figure 12) of the H5 One end of the (upper end of Figure 12) and the flying capacitor C FLY4 The high-side switch S H5 The other end of the flying capacitor C (the lower end in FIG. 12) is connected to the other end of the inductor L2 (the left end in FIG. 12). FLY4 The other end of the flying capacitor C (the end on the bottom side in FIG. 12) is connected to the other end of the inductor L1 (the end on the right side in FIG. 12). FLY2The other end (the end on the lower side in FIG. 12) of the (second output voltage drop suppression capacitor) is connected to the other end (the end on the right side in FIG. 12) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 12) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 12) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 12). A The other end (the lower end in Figure 12) of the H3 One end of the (upper end of Figure 12) and the flying capacitor C FLY2 12. The second output voltage drop suppression capacitor is connected to one end (the upper end in FIG. 12) of the second output voltage drop suppression capacitor. In another example, the output voltage drop suppression switch S A The other end (the lower end in FIG. 12) of the flying capacitor C FLY4 (the upper end in Figure 12) and the high-side switch S H5 12) and one end of the second wiring 11 (the upper end in FIG. 12). In yet another example, the output voltage drop suppression switch S A The other end (the end on the lower side in FIG. 12) may be connected to the other end (the end on the right side in FIG. 12) of the inductor L1.

[0089] 12, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", a phase "Phase A4", and a phase "Phase A5" to be described later. During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S ADuring steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", "PhaseA4", and "PhaseA5" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA5" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 12, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0090] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 12, the low-side switch S L1 and the low-side switch S L2is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and high-side switch S H5 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0091] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 12, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A2" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0092] In the phase "Phase A3" of the step-down power supply circuit 1 shown in Figure 12, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A3" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0093] In phase A4 of the step-down power supply circuit 1 shown in Figure 12, the high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch SH2 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 and flying capacitor C FLY4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A4" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0094] In phase A5 of the step-down power supply circuit 1 shown in Figure 12, the high-side switch S H5 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY4 From the high-side switch S H5 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A5" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 12, in the period before the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0095] In the example shown in FIG. 12, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 12 (i.e., during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S Aand flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 12, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 12, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase “Phase C”). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0096] The step-down power supply circuit 1 of the sixth embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the sixth embodiment (the second example of the step-down power supply circuit 1 of the sixth embodiment) is a step-down power supply circuit 1 of the sixth embodiment shown in FIG. IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0097] In the second example of the step-down power supply circuit 1 of the sixth embodiment, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the high-side switch S H1 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY4 From the high-side switch S H5 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0098] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2, high-side switch S H3 , high-side switch S H4 and high-side switch S H5 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0099] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4 and flying capacitor C FLY4A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the sixth embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0100] In the second example of the step-down power supply circuit 1 of the sixth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the sixth embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the sixth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the sixth embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0101] Seventh Embodiment A seventh embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the seventh embodiment is configured similarly to the step-down power supply circuit 1 of the sixth embodiment, except for the points described below. Therefore, the step-down power supply circuit 1 of the seventh embodiment can achieve the same effects as the step-down power supply circuit 1 of the sixth embodiment, except for the points described below.

[0102] As described above, the step-down power supply circuit 1 (Dixon type) of the sixth embodiment includes five high-side switches (specifically, high-side switches S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4and high-side switch S H5 ) and four flying capacitors (specifically, flying capacitors C FLY1 , flying capacitor C FLY2 , flying capacitor C FLY3 and flying capacitor C FLY4 ) and is equipped with. On the other hand, in a first example of the step-down power supply circuit 1 (Dixon type) of the seventh embodiment, the step-down power supply circuit 1 includes six or more high-side switches and five or more flying capacitors. More specifically, in the first example of the step-down power supply circuit 1 of the seventh embodiment, the step-down power supply circuit 1 includes (N+1) high-side switches (N is a natural number equal to or greater than 5) and N flying capacitors.

[0103] The first example of the step-down power supply circuit 1 of the seventh embodiment can be generalized as follows. Inductor L1 is connected to the voltage "V X1 (See Figure 12, etc.) and the voltage "V OUT (See Figure 12, etc.) The inductor L2 is located between the point indicated by the voltage "V X2 (See Figure 12, etc.) and the voltage "V OUT (See Figure 12, etc.) Low-side switch S L1 is the voltage "V X1 (See Figure 12) and ground. L2 is the voltage "V X2 (See Figure 12, etc.) and ground. To configure an N-stage step-down power supply circuit 1 (Dixon type), N flying capacitors (flying capacitors C FLY1 , flying capacitor C FLY2 , ..., flying capacitor C FLYN ) are required, and (N+1) high-side switches (high-side switch S H1 , high-side switch S H2 , …, high-side switch S HN+1 ) is required. (2M-1)th flying capacitor C FLY2M-1 (M is a natural number, and 2M-1 does not exceed N) is the voltage "V 2M-1 " and the voltage "V X2 (See Figure 12, etc.) 2Mth flying capacitor C FLY2M (M is a natural number, and 2M does not exceed N) is the voltage "V 2M-1 " and the voltage "V X1 (See Figure 12, etc.)

[0104] High-side switch S H1 is the input DC power supply V IN and the point indicated by voltage "V1" (see FIG. 12, etc.). The Kth high-side switch S HK (K is a natural number between 2 and N) is the voltage "V K-1 " and the voltage "V K " and is located between the points that can be expressed as ". When N is an odd number, the (N+1)th high-side switch S HN+1 is the voltage "V N " and the voltage "V X1 (See Figure 12, etc.) When N is an even number, the (N+1)th high-side switch S HN+1 is the voltage "V N " and the voltage "V X2 (See Figure 12, etc.) Output voltage drop suppression capacitor C A and output voltage drop suppression switch S A The branch in which these are connected in series is the input DC power supply V IN and voltage "V 2M (M is a natural number and 2M does not exceed N), or the input DC power supply V IN and voltage "V X1 (See Figure 12, etc.)

[0105] During steady operation of the first example of the step-down power supply circuit 1 of the seventh embodiment (when the output voltage drop suppression switch S A The generalized operating pattern for the MOSFETs (when the MOSFET is in the off state) is as follows: In phase "PhaseA2M-1" (M is a natural number and 2M-1 does not exceed N), the high-side switch S H2M-1 and the low-side switch S L1 is turned on. In phase "PhaseA2M" (M is a natural number and 2M does not exceed N), the high-side switch S H2M and the low-side switch S L2 is turned on. In phase "Phase B", the low-side switch S L1 and the low-side switch S L2 is turned on. During steady-state operation of the first example of the step-down power supply circuit 1 of the seventh embodiment, the phases are switched in the following order: "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → ... → "Phase AN" → "Phase B" → "Phase A1" → ... and this is repeated.

[0106] In the first example of the step-down power supply circuit 1 of the seventh embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, that is, when the load on the step-down power supply circuit 1 increases, the operation of phase "Phase C" is interrupted and executed (started). In phase "Phase C", the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 Therefore, the current I flowing through the inductor L1 L1 As the current I flows through the inductor L2, L2 As a result, the voltage V at the junction between the inductor L1 and the load LD increases.OUT This reduces the amount of drop in the voltage, thereby reducing the time it takes for the step-down power supply circuit 1 to return to a steady state, and improving the stability of the power supply including the step-down power supply circuit 1.

[0107] In the second example of the step-down power supply circuit 1 of the seventh embodiment, the step-down power supply circuit 1 is configured in the same manner as the first example of the step-down power supply circuit 1 of the seventh embodiment described above.

[0108] During steady operation of the second example of the step-down power supply circuit 1 of the seventh embodiment (output voltage drop suppression switch S A The generalized operating pattern for the MOSFETs (when the MOSFET is in the off state) is as follows: In phase "PhaseA1", the high-side switch S H1 , high-side switch S H3 , …, high-side switch S H2M-1 (M is a natural number and 2M-1 does not exceed N) and low-side switch S L1 is turned on. In phase "PhaseA2" (M is a natural number and 2M does not exceed N), the high-side switch S H2 , high-side switch S H4 , …, high-side switch S H2M (M is a natural number and 2M does not exceed N) and low-side switch S L2 is turned on. In phase "Phase B", the low-side switch S L1 and the low-side switch S L2 is turned on. During steady operation of the second example of the step-down power supply circuit 1 of the seventh embodiment, switching is repeated in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA1" → . . .

[0109] In the second example of the step-down power supply circuit 1 of the seventh embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, that is, when the load on the step-down power supply circuit 1 increases, the operation of phase "Phase C" is interrupted and executed (started). In phase "Phase C", the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 Therefore, the current I flowing through the inductor L1 L1 As the current I flows through the inductor L2, L2 As a result, the voltage V at the junction between the inductor L1 and the load LD increases. OUT This reduces the amount of drop in the voltage, thereby reducing the time it takes for the step-down power supply circuit 1 to return to a steady state, and improving the stability of the power supply including the step-down power supply circuit 1.

[0110] Eighth Embodiment An eighth embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the eighth embodiment is configured similarly to the step-down power supply circuit 1 of the second embodiment described above, except for the points described below. Therefore, the step-down power supply circuit 1 of the eighth embodiment can achieve the same effects as the step-down power supply circuit 1 of the second embodiment described above, except for the points described below.

[0111] FIG. 13 shows a step-down power supply circuit 1 according to the eighth embodiment, in which an input DC power supply V IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0112] In the example shown in FIG. 13, the step-down power supply circuit 1 of the eighth embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4and flying capacitor C FLY1 and a flying capacitor C that functions as a second output voltage drop suppression capacitor. FLY2 and flying capacitor C FLY3 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 13) and one end of the inductor L2 (the end on the right side in FIG. 13) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 13) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 13) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 13) is grounded.

[0113] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 13) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 13) of the FLY1 (the upper end in Figure 13) and the high-side switch S H2 13) is connected to one end of the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1The other end (the lower end in FIG. 13) of the FLY3 (the upper end in Figure 13) and the high-side switch S H4 13. The upper end of the first embodiment is connected to the other end of the second embodiment (the upper end in FIG. 13). High-side switch S H2 The other end (the lower end in Figure 13) of the H3 One end of the (upper end of Figure 13) and the flying capacitor C FLY2 The high-side switch S H3 The other end (the lower end in FIG. 13) of the FLY3 (the upper end in Figure 13) and the high-side switch S H4 The flying capacitor C is connected to one end of the flying capacitor C (the upper end in FIG. 13). FLY3 The other end (the end on the lower side in FIG. 13) of the high-side switch S is connected to the other end (the end on the left side in FIG. 13) of the inductor L2. H4 The other end of the flying capacitor C (the lower end in FIG. 13) is connected to the other end of the inductor L1 (the right end in FIG. 13). FLY2 The other end (the end on the lower side in FIG. 13) of the (second output voltage drop suppression capacitor) is connected to the other end (the end on the right side in FIG. 13) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 13) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 13) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 13). A The other end (the lower end in Figure 13) of the H3One end of the (upper end of Figure 13) and the flying capacitor C FLY2 13) (the second output voltage drop suppression capacitor).

[0114] 13, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", and a phase "Phase A4" to be described later. During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", and "PhaseA4" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 13, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 13, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0115] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 13, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 13, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0116] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 13, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L1As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A2" of the step-down power supply circuit 1 shown in FIG. 13, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0117] In the phase "Phase A3" of the step-down power supply circuit 1 shown in Figure 13, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A3" of the step-down power supply circuit 1 shown in FIG. 13, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0118] In phase A4 of the step-down power supply circuit 1 shown in Figure 13, the high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A4" of the step-down power supply circuit 1 shown in FIG. 13, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the example shown in FIG. 13, in the period before the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0119] In the example shown in FIG. 13, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S AThe operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 13 (that is, during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 13, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 13, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase “Phase C”). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0120] The step-down power supply circuit 1 of the eighth embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the eighth embodiment (the second example of the step-down power supply circuit 1 of the eighth embodiment) is a step-down power supply circuit 1 of the eighth embodiment shown in FIG. 13, which is connected to an input DC power supply V IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0121] In the second example of the step-down power supply circuit 1 of the eighth embodiment, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current IL2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0122] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0123] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the high-side switch S H2, high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the eighth embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I flowing through the load LD LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0124] In the second example of the step-down power supply circuit 1 of the eighth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the eighth embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the eighth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the eighth embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0125] Ninth Embodiment A ninth embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the ninth embodiment is configured similarly to the step-down power supply circuit 1 of the third embodiment, except for the points described below. Therefore, the step-down power supply circuit 1 of the ninth embodiment can achieve the same effects as the step-down power supply circuit 1 of the third embodiment, except for the points described below.

[0126] FIG. 14 shows a step-down power supply circuit 1 according to the ninth embodiment, in which an input DC power supply V IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0127] In the example shown in FIG. 14, the step-down power supply circuit 1 of the ninth embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4 and flying capacitor C FLY1 and flying capacitor C FLY2 and flying capacitor C FLY3 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 14) and one end of the inductor L2 (the end on the right side in FIG. 14) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 14) is connected to the low-side switch S L1 The low-side switch S L1The other end of the inductor L2 (the end on the left side in FIG. 14) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 14) is grounded.

[0128] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 14) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 14) of the FLY1 (the upper end in Figure 14) and the high-side switch S H2 14) is connected to one end of the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the lower end in FIG. 14) of the FLY3 (the upper end in Figure 14) and the high-side switch S H4 14. The upper end of the first embodiment is connected to the other end of the second embodiment (the upper end in FIG. 14). High-side switch S H2 The other end (the lower end in Figure 14) of the H3 One end of the (upper end of Figure 14) and the flying capacitor C FLY2 The high-side switch S H3 The other end (the lower end in FIG. 14) of the FLY3 (the upper end in Figure 14) and the high-side switch S H4 The flying capacitor C is connected to one end of the capacitor C (the upper end in FIG. 14). FLY3The other end (the end on the lower side in FIG. 14) of the high-side switch S is connected to the other end (the end on the left side in FIG. 14) of the inductor L2. H4 The other end of the flying capacitor C (the lower end in FIG. 14) is connected to the other end of the inductor L1 (the right end in FIG. 14). FLY2 The other end (the end on the lower side in FIG. 14) is connected to the other end (the end on the right side in FIG. 14) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 14) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 14) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 14). A The other end (the end on the lower side in FIG. 14) is connected to the other end (the end on the right side in FIG. 14) of the inductor L1.

[0129] 14, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", and a phase "Phase A4". During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", and "PhaseA4" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 14, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 14, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0130] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 14, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 14, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0131] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 14, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0132] In phase A3 of the step-down power supply circuit 1 shown in Figure 14, the high-side switch S H3 and the low-side switch S L1is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in phase "PhaseA3", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0133] In phase A4 of the step-down power supply circuit 1 shown in Figure 14, the high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA4", the low-side switch SL1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the example shown in FIG. 14, in the period before the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0134] In the example shown in FIG. 14, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 14 (that is, during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current IL1 increases. In detail, in the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 14, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 14, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase “Phase C”). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0135] The step-down power supply circuit 1 of the ninth embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit applied to the ninth embodiment (the second example of the step-down power supply circuit 1 of the ninth embodiment) is a circuit in which the step-down power supply circuit 1 of the ninth embodiment shown in FIG. IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0136] In the second example of the step-down power supply circuit 1 of the ninth embodiment, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the ninth embodiment, the high-side switch S H1 , high-side switch S H3and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the ninth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0137] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the ninth embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 and high-side switch S H4 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the ninth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0138] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the ninth embodiment, the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the ninth embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0139] In the second example of the step-down power supply circuit 1 of the ninth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the ninth embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the ninth embodiment, the low-side switch S L1and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the ninth embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0140] Tenth Embodiment A step-down power supply circuit according to a tenth embodiment of the present invention will now be described. The step-down power supply circuit 1 of the tenth embodiment is configured similarly to the step-down power supply circuit 1 of the eighth embodiment, except for the points that will be described later. Therefore, the step-down power supply circuit 1 of the tenth embodiment can achieve the same effects as the step-down power supply circuit 1 of the eighth embodiment, except for the points that will be described later.

[0141] FIG. 15 shows a step-down power supply circuit 1 according to the tenth embodiment. IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0142] In the example shown in FIG. 15, the step-down power supply circuit 1 of the tenth embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4 and the high-side switch S H5 and flying capacitor C FLY1 and a flying capacitor C that functions as a second output voltage drop suppression capacitor. FLY2 and flying capacitor C FLY3and a flying capacitor C that functions as a second output voltage drop suppression capacitor. FLY4 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 15) and one end of the inductor L2 (the end on the right side in FIG. 15) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 15) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 15) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 15) is grounded.

[0143] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 15) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 15) of the FLY1 (the upper end in Figure 15) and the high-side switch S H2 15) is connected to one end of the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the lower end in FIG. 15) of the FLY3(the upper end in Figure 15) and the high-side switch S H4 15. The upper end of the first electrode 14 is connected to the other end of the first electrode 14 (the upper end in FIG. 15). High-side switch S H2 The other end (the lower end in Figure 15) of the H3 One end of the (upper end of Figure 15) and the flying capacitor C FLY2 The flying capacitor C is connected to one end of the FLY2 The other end (the lower end in FIG. 15) of the second output voltage drop suppression capacitor is connected to the high-side switch S H5 One end of the (upper end of Figure 12) and the flying capacitor C FLY4 The high-side switch S is connected to one end (the upper end in FIG. 15) of the second output voltage drop suppression capacitor. H3 The other end (the lower end in FIG. 15) of the FLY3 (the upper end in Figure 15) and the high-side switch S H4 The flying capacitor C is connected to one end of the FLY3 The other end (the end on the lower side in FIG. 15) of the inductor L1 is connected to the other end (the end on the left side in FIG. 15) of the inductor L2. High-side switch S H4 The other end (the lower end in Figure 15) of the H5 One end of the (upper end of Figure 12) and the flying capacitor C FLY4 The high-side switch S H5 The other end of the flying capacitor C (the end on the bottom side in FIG. 15) is connected to the other end of the inductor L2 (the end on the left side in FIG. 15). FLY4 The other end (the end on the lower side in FIG. 15) of the (second output voltage drop suppression capacitor) is connected to the other end (the end on the right side in FIG. 12) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 15) is connected to the input DC power supply V INThat is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 15) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end (the upper end in FIG. 15). A The other end (the lower end in Figure 15) of the H3 One end of the (upper end of Figure 15) and the flying capacitor C FLY2 15. The second output voltage drop suppression capacitor is connected to one end (the upper end in FIG. 15) of the second output voltage drop suppression capacitor. In another example, the output voltage drop suppression switch S A The other end (the lower end in FIG. 15) of the flying capacitor C FLY4 (the upper end in Figure 15) and the high-side switch S H5 15. Alternatively, the other end of the first wiring 10 may be connected to the other end of the second wiring 10 (the upper end in FIG. 15). In yet another example, the output voltage drop suppression switch S A The other end (the end on the lower side in FIG. 15) may be connected to the other end (the end on the right side in FIG. 15) of the inductor L1.

[0144] 15, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", a phase "Phase A4", and a phase "Phase A5" to be described later. During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S ADuring steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", "PhaseA4", and "PhaseA5" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA5" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 15, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0145] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 15, the low-side switch S L1 and the low-side switch SL2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and high-side switch S H5 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0146] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 15, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 and flying capacitor C FLY4A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A2" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0147] In the phase "Phase A3" of the step-down power supply circuit 1 shown in Figure 15, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A3" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0148] In phase A4 of the step-down power supply circuit 1 shown in Figure 15, the high-side switch S H4and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 and flying capacitor C FLY4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase A4" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0149] In the phase "Phase A5" of the step-down power supply circuit 1 shown in Figure 15, the high-side switch S H5 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY4 From the high-side switch S H5 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A5" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 15, in the period before the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0150] In the example shown in FIG. 15, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 15 (that is, during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 (Second output voltage drop suppression capacitor) and flying capacitor C FLY4 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In the example of FIG. 15, the second output voltage drop suppression capacitor is two flying capacitors C FLY2 and C FLY4 The second capacitor for suppressing a drop in output voltage is not limited to being a single capacitor, but may be two or more capacitors connected in series. Furthermore, as shown in this example, even when the second capacitor for suppressing a drop in output voltage is a series-connected capacitor, it goes without saying that a series-connected flying capacitor can function as the second capacitor for suppressing a drop in output voltage. In detail, in the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 15, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 15, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase “Phase C”). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0151] The step-down power supply circuit 1 of the tenth embodiment is IN , load LD and output smoothing capacitor C OUTThe second example of the circuit applied to the step-down power supply circuit 1 of the tenth embodiment is shown in FIG. 15. IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0152] In the second example of the step-down power supply circuit 1 of the tenth embodiment, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the high-side switch S H1 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY4 From the high-side switch S H5A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0153] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and high-side switch S H5 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0154] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 and flying capacitor C FLY4 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4 and flying capacitor C FLY4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the tenth embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0155] In the second example of the step-down power supply circuit 1 of the tenth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the tenth embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A and flying capacitor C FLY2 (Second output voltage drop suppression capacitor) and flying capacitor C FLY4 A current flows to the load LD via the second output voltage drop suppression capacitor and the inductor L1. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the tenth embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2becomes high. In the second example of the step-down power supply circuit 1 of the tenth embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0156] Eleventh Embodiment An eleventh embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the eleventh embodiment is configured similarly to the step-down power supply circuit 1 of the fifth embodiment, except for the points described below. Therefore, the step-down power supply circuit 1 of the first embodiment can achieve the same effects as the step-down power supply circuit 1 of the eighth embodiment, except for the points described below.

[0157] FIG. 16 shows a step-down power supply circuit 1 according to the eleventh embodiment. IN , load LD and output smoothing capacitor C OUT FIG. 1 is a diagram showing a first example of a circuit applied to the present invention.

[0158] In the example shown in FIG. 16, the step-down power supply circuit 1 of the eleventh embodiment includes an inductor L1, an inductor L2, and a low-side switch S L1 and the low-side switch S L2 and the high-side switch S H1 and the high-side switch S H2 and the high-side switch S H3 and the high-side switch S H4 and the high-side switch S H5 and flying capacitor C FLY1 and flying capacitor C FLY2 and flying capacitor C FLY3 and flying capacitor C FLY4 and the output voltage drop suppression capacitor C A and the output voltage drop suppression switch S A It is equipped with the following. The inductor L1 is connected to the load LD. The inductor L2 is connected in parallel to the inductor L1. The output smoothing capacitor C OUT are connected in parallel to the load LD. Specifically, one end of the inductor L1 (the end on the left side in FIG. 16) and one end of the inductor L2 (the end on the right side in FIG. 16) are connected to the load LD. The other end of the inductor L1 (the end on the right side in FIG. 16) is connected to the low-side switch S L1 The low-side switch S L1 The other end of the inductor L2 (the end on the left side in FIG. 16) is connected to ground. L2 The low-side switch S L2 The other end (the lower end in FIG. 16) is grounded.

[0159] High-side switch S H1 is the input DC power supply V IN In detail, the high-side switch S H1 One end of the (upper end in Figure 16) is connected to the input DC power supply V IN High-side switch S H1 The other end (the lower end in FIG. 16) of the FLY1 (the upper end in Figure 16) and the high-side switch S H2 16) is connected to one end of the high-side switch S H2 is the flying capacitor C FLY1 A high-side switch S H1 Connected to the flying capacitor C FLY1 The other end (the end on the lower side in FIG. 16) of the high-side switch S is connected to the other end (the end on the left side in FIG. 16) of the inductor L2. H2 The other end (the lower end in Figure 16) of the H3 One end of the (upper end of Figure 16) and the flying capacitor C FLY2The high-side switch S H3 The other end (the lower end in FIG. 16) of the FLY3 (the upper end in Figure 16) and the high-side switch S H4 The flying capacitor C is connected to one end of the capacitor C (the upper end in FIG. 16). FLY3 The other end (the end on the lower side in FIG. 16) of the high-side switch S is connected to the other end (the end on the left side in FIG. 16) of the inductor L2. H4 The other end (the lower end in Figure 16) of the H5 One end of the (upper end of Figure 16) and the flying capacitor C FLY4 The flying capacitor C is connected to one end of the capacitor C (the upper end in FIG. 16). FLY4 The other end (the end on the lower side in FIG. 16) of the high-side switch S is connected to the other end (the end on the right side in FIG. 16) of the inductor L1. H5 The other end of the flying capacitor C (the end on the bottom side in FIG. 16) is connected to the other end of the inductor L2 (the end on the left side in FIG. 16). FLY2 The other end (the end on the lower side in FIG. 16) is connected to the other end (the end on the right side in FIG. 16) of the inductor L1. Output voltage drop suppression capacitor C A One end of the (upper end in Figure 16) is connected to the input DC power supply V IN That is, the output voltage drop suppression capacitor C A is the first high-side switch S H1 In parallel with the input DC power supply V IN The output voltage drop suppression capacitor C A The other end (the lower end in FIG. 16) of the output voltage drop suppression switch S A The output voltage drop suppression switch S is connected to one end of the output voltage drop suppression switch S (the upper end in FIG. 16). A The other end (the end on the lower side in FIG. 16) is connected to the other end (the end on the right side in FIG. 16) of the inductor L1.

[0160] 16, the steady state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", a phase "Phase A2", a phase "Phase A3", a phase "Phase A4", and a phase "Phase A5". During the steady state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S A During steady-state operation of the step-down power supply circuit 1, phases "PhaseA1", "PhaseB", "PhaseA2", "PhaseA3", "PhaseA4", and "PhaseA5" are switched repeatedly in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA3" → "PhaseB" → "PhaseA4" → "PhaseB" → "PhaseA5" → "PhaseB" → "PhaseA1" → ... In the phase "Phase A1" of the step-down power supply circuit 1 shown in Figure 16, the high-side switch S H1 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A1" of the step-down power supply circuit 1 shown in FIG. 16, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2and the voltage V at the connection point with inductor L2 X2 becomes high.

[0161] In phase "Phase B" of the step-down power supply circuit 1 shown in Figure 16, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and high-side switch S H5 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase B" of the step-down power supply circuit 1 shown in FIG. 16, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0162] In the phase "Phase A2" of the step-down power supply circuit 1 shown in Figure 16, the high-side switch S H2 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current IL2 Also, the flying capacitor C FLY1 From the high-side switch S H2 and flying capacitor C FLY2 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0163] In phase "Phase A3" of the step-down power supply circuit 1 shown in Figure 16, the high-side switch S H3 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H4 , high-side switch S H5 and the low-side switch S L2 As a result, the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in phase "PhaseA3", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0164] In phase A4 of the step-down power supply circuit 1 shown in Figure 16, the high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY3 From the high-side switch S H4 and flying capacitor C FLY4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA4", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0165] In the phase "Phase A5" of the step-down power supply circuit 1 shown in Figure 16, the high-side switch S H5 and the low-side switch S L1 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and the low-side switch S L2 As a result, the flying capacitor C FLY4 From the high-side switch S H5 A current flows through the inductor L2 to the load LD. That is, the current I L2Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase "Phase A5" of the step-down power supply circuit 1 shown in FIG. 16, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 16, in the period before the point at which the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0166] In the example shown in FIG. 16, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 16 (that is, during the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 , low-side switch S L1 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase "Phase C" of the step-down power supply circuit 1 shown in FIG. 16, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the example shown in FIG. 16, the current I flowing through the load LD increases as the resistance of the load LD decreases (at the start of phase “Phase C”). LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0167] The step-down power supply circuit 1 of the eleventh embodiment is IN , load LD and output smoothing capacitor C OUT The second example of the circuit (second example of the step-down power supply circuit 1 of the eleventh embodiment) applied to the eleventh embodiment is a step-down power supply circuit 1 of the eleventh embodiment shown in FIG. IN , load LD and output smoothing capacitor C OUT It is configured in the same manner as the first example of the circuit applied to.

[0168] In the second example of the step-down power supply circuit 1 of the eleventh embodiment, the steady-state operation of the step-down power supply circuit 1 includes a phase "Phase A1", a phase "Phase B", and a phase "Phase A2". During the steady-state operation of the step-down power supply circuit 1 (steady operation), the output voltage drop suppression switch S ADuring steady-state operation of the step-down power supply circuit 1, the phases "Phase A1", "Phase B", and "Phase A2" are switched repeatedly in the order "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → "Phase A1" → ... In the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the eleventh embodiment, the high-side switch S H1 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 is turned on, and the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY2 From the high-side switch S H3 and flying capacitor C FLY3 A current flows through the load LD via the inductor L2 and the flying capacitor C FLY4 From the high-side switch S H5 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase A1” of the second example of the step-down power supply circuit 1 of the eleventh embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high.

[0169] In the phase “Phase B” of the second example of the step-down power supply circuit 1 of the eleventh embodiment, the low-side switch S L1 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H2 , high-side switch S H3 , high-side switch S H4 and high-side switch S H5 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the low-side switch S L1 A current flows through the inductor L1 and the load LD. That is, the current I L1 decreases. In detail, in the phase “Phase B” of the second example of the step-down power supply circuit 1 of the eleventh embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 is low, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low.

[0170] In the phase “Phase A2” of the second example of the step-down power supply circuit 1 of the eleventh embodiment, the high-side switch S H2 , high-side switch S H4 and the low-side switch S L2 is turned on, and the high-side switch S H1 , high-side switch S H3 , high-side switch S H5 and the low-side switch S L1 As a result, the low-side switch S L2 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the flying capacitor C FLY1 From the high-side switch SH2 and flying capacitor C FLY2 A current flows through the load LD via the inductor L1 and the flying capacitor C FLY3 From the high-side switch S H4 and flying capacitor C FLY4 A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in phase "PhaseA2", the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes low. In the second example of the step-down power supply circuit 1 of the eleventh embodiment, in the period before the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively small (i.e., the current I LOAD / 2 is also a relatively small value).

[0171] In the second example of the step-down power supply circuit 1 of the eleventh embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, the output voltage drop suppression switch S A The operation of phase "Phase C" when the is turned on is interrupted and executed (started). In the phase "Phase C" of the second example of the step-down power supply circuit 1 of the eleventh embodiment (that is, during the execution of the operation of the phase "Phase C"), the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the high-side switch S H2 , high-side switch S H3 , high-side switch S H4 , high-side switch S H5 , low-side switch S L1 and the low-side switch SL2 As a result, the input DC power supply V IN From the high-side switch S H1 and flying capacitor C FLY1 A current flows through the inductor L2 to the load LD. That is, the current I L2 Also, the input DC power supply V IN to output voltage drop suppression capacitor C A and output voltage drop suppression switch S A A current flows through the inductor L1 and the load LD. That is, the current I L1 increases. In detail, in the phase “Phase C” of the second example of the step-down power supply circuit 1 of the eleventh embodiment, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 becomes high. In the second example of the step-down power supply circuit 1 of the eleventh embodiment, in the period after the point in time when the current flowing through the load LD increases as the resistance of the load LD decreases (the start point of phase “Phase C”), the current I LOAD becomes relatively large (i.e., the current I LOAD / 2 is also a relatively large value).

[0172] <Twelfth embodiment> A twelfth embodiment of the step-down power supply circuit of the present invention will now be described. The step-down power supply circuit 1 of the twelfth embodiment is configured similarly to the step-down power supply circuit 1 of the tenth embodiment, except for the points described below. Therefore, the step-down power supply circuit 1 of the twelfth embodiment can achieve the same effects as the step-down power supply circuit 1 of the tenth embodiment, except for the points described below.

[0173] As described above, the step-down power supply circuit 1 (ladder type) of the tenth embodiment includes five high-side switches (specifically, high-side switches S H1 , high-side switch SH2 , high-side switch S H3 , high-side switch S H4 and high-side switch S H5 ) and four flying capacitors (specifically, flying capacitors C FLY1 , flying capacitor C FLY2 , flying capacitor C FLY3 and flying capacitor C FLY4 ) and is equipped with. On the other hand, in a first example of the step-down power supply circuit 1 (ladder type) of the twelfth embodiment, the step-down power supply circuit 1 includes six or more high-side switches and five or more flying capacitors. More specifically, in the first example of the step-down power supply circuit 1 of the seventh embodiment, the step-down power supply circuit 1 includes (N+1) high-side switches (N is a natural number equal to or greater than 5) and N flying capacitors.

[0174] The first example of the step-down power supply circuit 1 of the twelfth embodiment can be generalized as follows. Inductor L1 is connected to the voltage "V X1 (See Figure 15, etc.) and the voltage "V OUT (See Figure 15, etc.) The inductor L2 is located between the point indicated by the voltage "V X2 (See Figure 15, etc.) and the voltage "V OUT (See Figure 15, etc.) Low-side switch S L1 is the voltage "V X1 (See Figure 15) and ground. L2 is the voltage "V X2 (See Figure 15, etc.) and ground. To configure an N-stage step-down power supply circuit 1 (ladder type), N flying capacitors (flying capacitors C FLY1 , flying capacitor C FLY2 , ..., flying capacitor C FLYN ) are required, and (N+1) high-side switches (high-side switch S H1 , high-side switch S H2, …, high-side switch S HN+1 ) is required. Kth flying capacitor C FLYK (K is a natural number between 1 and N-2) is the voltage "V K " and the voltage "V K+2 " and is located between the points that can be expressed as ". When N is odd, the flying capacitor C FLYN-1 is the voltage "V N-1 " and the voltage "V X1 " (See Figure 15, etc.) and the flying capacitor C FLYN is the voltage "V N " and the voltage "V X2 (See Figure 15, etc.) When N is an even number, the flying capacitor C FLYN-1 is the voltage "V N-1 " and the voltage "V X2 " (See Figure 15, etc.) and the flying capacitor C FLYN is the voltage "V N " and the voltage "V X1 (See Figure 15, etc.)

[0175] High-side switch S H1 is the input DC power supply V IN and the point indicated by voltage "V1" (see FIG. 15, etc.). The Kth high-side switch S HK (K is a natural number between 2 and N) is the voltage "V K-1 " and the voltage "V K " and is located between the points that can be expressed as ". When N is an odd number, the (N+1)th high-side switch S HN+1 is the voltage "V N " and the voltage "V X1 (See Figure 15, etc.) When N is an even number, the (N+1)th high-side switch S HN+1 is the voltage "V N " and the voltage "V X2(See Figure 15, etc.) Output voltage drop suppression capacitor C A and output voltage drop suppression switch S A The branch in which these are connected in series is the input DC power supply V IN and voltage "V 2M (M is a natural number and 2M does not exceed N), or the input DC power supply V IN and voltage "V X1 (See Figure 15, etc.)

[0176] During steady operation of the first example of the step-down power supply circuit 1 of the twelfth embodiment (when the output voltage drop suppression switch S A The generalized operating pattern for the MOSFETs (when the MOSFET is in the off state) is as follows: In phase "PhaseA2M-1" (M is a natural number and 2M-1 does not exceed N), the high-side switch S H2M-1 and the low-side switch S L1 is turned on. In phase "PhaseA2M" (M is a natural number and 2M does not exceed N), the high-side switch S H2M and the low-side switch S L2 is turned on. In phase "Phase B", the low-side switch S L1 and the low-side switch S L2 is turned on. During steady-state operation of the first example of the step-down power supply circuit 1 of the twelfth embodiment, the phases are switched in the following order: "Phase A1" → "Phase B" → "Phase A2" → "Phase B" → ... → "Phase AN" → "Phase B" → "Phase A1" → ... and this is repeated.

[0177] In the first example of the step-down power supply circuit 1 of the twelfth embodiment, the current I LOAD When the load on the step-down power supply circuit 1 increases, that is, when the load on the step-down power supply circuit 1 increases, the operation of phase "Phase C" is interrupted and executed (started). In phase "Phase C", the output voltage drop suppression switch SA and high-side switch S H1 is turned on, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 Therefore, the current I flowing through the inductor L1 L1 As the current I flows through the inductor L2, L2 As a result, the voltage V at the junction between the inductor L1 and the load LD increases. OUT This reduces the amount of drop in the voltage, thereby reducing the time it takes for the step-down power supply circuit 1 to return to a steady state, and improving the stability of the power supply including the step-down power supply circuit 1.

[0178] In the second example of the step-down power supply circuit 1 of the twelfth embodiment, the step-down power supply circuit 1 is configured in the same manner as the first example of the step-down power supply circuit 1 of the twelfth embodiment described above.

[0179] In the steady state operation of the second example of the step-down power supply circuit 1 of the twelfth embodiment (the output voltage drop suppression switch S A The generalized operating pattern for the MOSFETs (when the MOSFET is in the off state) is as follows: In phase "PhaseA1", the high-side switch S H1 , high-side switch S H3 , …, high-side switch S H2M-1 (M is a natural number and 2M-1 does not exceed N) and low-side switch S L1 is turned on. In phase "PhaseA2" (M is a natural number and 2M does not exceed N), the high-side switch S H2 , high-side switch S H4 , …, high-side switch S H2M (M is a natural number and 2M does not exceed N) and low-side switch S L2 is turned on. In phase "Phase B", the low-side switch S L1 and the low-side switch SL2 is turned on. During steady operation of the second example of the step-down power supply circuit 1 of the twelfth embodiment, switching is repeated in the order of "PhaseA1" → "PhaseB" → "PhaseA2" → "PhaseB" → "PhaseA1" → . . .

[0180] In the second example of the step-down power supply circuit 1 of the twelfth embodiment, the current I flowing through the load LD decreases as the resistance of the load LD decreases. LOAD When the load on the step-down power supply circuit 1 increases, that is, when the load on the step-down power supply circuit 1 increases, the operation of phase "Phase C" is interrupted and executed (started). In phase "Phase C", the output voltage drop suppression switch S A and high-side switch S H1 is turned on, and the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 becomes high, and the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 Therefore, the current I flowing through the inductor L1 L1 As the current I flows through the inductor L2, L2 As a result, the voltage V at the junction between the inductor L1 and the load LD increases. OUT This reduces the amount of drop in the voltage, thereby reducing the time it takes for the step-down power supply circuit 1 to return to a steady state, and improving the stability of the power supply including the step-down power supply circuit 1.

[0181] [Example] The present inventors have confirmed the effect of the present invention through simulation using a 0.25 μm BCD process, using Cadence Spectre as the simulator. Figure 17 shows an outline of the simulation circuit. The main circuit (Power Stage) is a high-side switch S H1 ~High-side switch S H6 and flying capacitor C FLY1 ~Flying Capacitor C FLY5In Figure 17, the C FLY is the flying capacitor C FLY1 ~Flying Capacitor C FLY5 and output voltage drop suppression capacitor C A The capacitance of the flying capacitor used is 500nF. The inductance is 330nH. BST is the value of the bootstrap capacitance used in the gate driver inside the Power Stage. Figure 18 shows an overview of the internal structure of the control circuit (Control). Phase compensation is based on two-phase Type-III control, and V CMP1 and V CMP2 However, the low-side switch S L1 and the voltage V at the connection point with inductor L1 X1 and the waveform of the low-side switch S L2 and the voltage V at the connection point with inductor L2 X2 The high-side switch S H1 ~High-side switch S H6 and the low-side switch S L1 and the low-side switch S L2 and output voltage drop suppression switch S A and control.

[0182] Figure 19 shows the waveform of the control circuit. As shown in Figure 19, in this control circuit, when the EN_VEAHLIM control terminal is H, the output V after the multiplexer of the error amplifier (EA) MUX But V EA_HLIM The value of V EA_HLIM By setting the value of V appropriately, V CMP1 and V CMP2 and become high level (V MUX V RAM1 and V RAM2 This prevents the voltage drop when both voltages are larger than the V, and allows it to function as a control for conventional circuits. On the other hand, when the EN_VEAHLIM control terminal is set to L, VMUX The value of V EA_HLIM Since values ​​above this can be output, V CMP1 and V CMP2 This allows both to be at a high level. Figure 20 shows the V IN =24V, V OUT V during load fluctuation when = 1V and switching frequency is 2.5MHz OUT The load resistance is switched from 50Ω to 0.25Ω (corresponding to an increase in the load current from 20mA to 4A). In this case, the proposed method of the present invention has a higher V OUT It has been shown that the decline in blood glucose is suppressed and the recovery time is short.

[0183] Although the present invention has been described above using the embodiments, the present invention is not limited to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. The configurations described in the above-described embodiments and examples may be combined. [Explanation of symbols]

[0184] 1...Step-down power supply circuit, L1...inductor, L2...inductor, S L1 …low-side switch, S L2 …low-side switch, S H1 …High-side switch, S H2 …High-side switch, S H3 …High-side switch, S H4 …High-side switch, S H5 …High-side switch, C FLY1 …flying capacitor, C FLY2 …flying capacitor, C FLY3 …flying capacitor, C FLY4 …flying capacitor, C A ...output voltage drop suppression capacitor, S A …Output voltage drop suppression switch, V IN …input DC power supply, LD…load, C OUT …Output smoothing capacitor

Claims

1. a first inductor connected to the load; a second inductor connected in parallel to the first inductor to the load; a first low-side switch; a second low-side switch; a first high-side switch connected to the input DC power supply; a first flying capacitor connected to the first high-side switch; a second high-side switch connected in parallel to the first flying capacitor and the first high-side switch; an output voltage drop suppression capacitor connected in parallel to the first high-side switch; a step-down power supply circuit including at least an output voltage drop suppression switch connected in series to the output voltage drop suppression capacitor, one end of the first inductor and one end of the second inductor are connected to the load; the other end of the first inductor is connected to one end of the first low-side switch; the other end of the first low-side switch is connected to ground; the other end of the second inductor is connected to one end of the second low-side switch; the other end of the second low-side switch is connected to the ground; During steady operation of the step-down power supply circuit, the output voltage drop suppression switch is in an off state. a first phase in which a current flows from the input DC power supply to the load via at least the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the ground to the load via the first low-side switch and the first inductor; a second phase in which current flows from the ground through the second low-side switch and the second inductor to the load, and from the ground through the first low-side switch and the first inductor to the load; a third phase in which a current flows from the ground to the load via the second low-side switch and the second inductor, and a third phase in which a current flows from the first flying capacitor to the load via at least the second high-side switch and the first inductor, is switched, whereby a current of a first magnitude flows to the load; When the load of the step-down power supply circuit increases, the current flowing through the load increases as the resistance of the load decreases. The output voltage drop suppression switch is turned on, a fourth phase in which a current flows from the input DC power supply to the load via at least the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the input DC power supply to the load via at least the output voltage drop suppression capacitor, the output voltage drop suppression switch, and the first inductor, and a current of a second magnitude larger than the first magnitude flows through the load; Step-down power supply circuit.

2. one end of the output voltage drop suppression capacitor is connected to the input DC power supply; the other end of the output voltage drop suppression capacitor is connected to one end of the output voltage drop suppression switch; the other end of the output voltage drop suppression switch is connected to the other end of the first inductor, In the fourth phase, the output voltage drop suppression switch and the first high-side switch are turned on, and the second high-side switch, the first low-side switch, and the second low-side switch are turned off, so that a current flows from the input DC power supply to the load via the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the input DC power supply to the load via the output voltage drop suppression capacitor, the output voltage drop suppression switch, and the first inductor.

2. The step-down power supply circuit according to claim 1.

3. a second output voltage drop suppression capacitor; one end of the output voltage drop suppression capacitor is connected to the input DC power supply; the other end of the output voltage drop suppression capacitor is connected to one end of the output voltage drop suppression switch; the other end of the output voltage drop suppression switch is connected to one end of the second output voltage drop suppression capacitor; the other end of the second output voltage drop suppression capacitor is connected to the other end of the first inductor; In the fourth phase, the output voltage drop suppression switch and the first high-side switch are turned on, and the second high-side switch, the first low-side switch, and the second low-side switch are turned off, so that a current flows from the input DC power supply to the load via the first high-side switch, the first flying capacitor, and the second inductor, and a current flows from the input DC power supply to the load via the output voltage drop suppression capacitor, the output voltage drop suppression switch, the second output voltage drop suppression capacitor, and the first inductor.

2. The step-down power supply circuit according to claim 1.

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