Switching regulator that adaptively detects zero current and control method thereof

Abstract

Embodiments of the present invention include a first switch block, a second switch block, a third switch block, and a fourth switch block connected in series with each other. A flying capacitor is connected to a first node where the first switch block and the second switch block are connected and a second node where the third switch block and the fourth switch block are connected. An inductor is connected to a third node where the second switch block and the third switch block are connected. A switching regulator is provided, which includes a control circuit that compares the current value of one of the first switch block, the second switch block, the third switch block, and the fourth switch block with a zero-current detection reference value to control zero-current switching for the one switch block, compares the voltage value at one end and the voltage value at the other end of the one switch block confirmed at a moment after zero-current switching, and adjusts the zero-current detection reference value.

Description

Technical Field

[0001] This embodiment relates to a switching regulator.

Background Art

[0002] A switching regulator is an important component in electronic devices, which effectively performs power conversion and voltage control and plays a role in maintaining the stability and efficiency of electronic devices. However, when turning on or off the switch in the switching regulator, switching losses inevitably occur, and sometimes noise including electromagnetic waves can be generated.

[0003] In order to solve such problems and improve the performance of the switching regulator, generally, the switching regulator can use a method of detecting and controlling zero current. The switching regulator can minimize unnecessary energy loss and achieve stable operation by turning on or off the switch in the zero current state. However, there may be a time difference between the time when zero current is detected and the time when the switch is zero current switched. This can be caused by delays due to circuit configuration or switching operations. Due to such a time difference, the above problems have not been completely solved.

[0004] FIG. 1 is a diagram for explaining the problem that zero current switching is not perfectly performed in a switching regulator according to the prior art.

[0005] Referring to FIG. 1, the switching regulator can compare the switch current value with the zero current detection reference value at the first time point T1. Then, the switching regulator can turn off the switch at the second time point T2 according to the comparison result.

[0006] A certain time delay can exist between the first time point T1 and the second time point T2. Such a time delay can occur in the process of comparing the switch current value with the detection reference value of zero current, and can occur in the switch control operation of supplying a gate signal to the switch to turn off the switch.

[0007] Due to the time delay between the time point T1 when the switch current value is compared with the detection reference value of zero current and the time point T2 when the switch turns off, the switching regulator can set the absolute value of the detection reference value of zero current to a value higher than substantially 0 (A). In FIG. 1, in the case of the first current curve 10, the switching regulator set the detection reference value of zero current higher than 0 (A). However, with such a setting, when the current value (current value 1) of the switch became substantially 0 (A) at the second time point T2, it turned off.

[0008] However, in the case of the second current curve 11 in FIG. 1, although the switching regulator set the detection reference value of zero current in the same manner as in the above example, the gradient of the switch current value was different, and at the second time point T2, the current value (current value 2) of the switch turned off in a state having a value lower than 0 (A). When the current value of the switch becomes lower or higher than 0 (A) at the time when the switch turns off in this way, zero current switching is not performed perfectly, and the effect of reducing switching loss and noise also decreases.

[0009] In the process of mass-producing the switching regulator, the detection reference value of zero current can be adjusted through testing and then shipped. However, since such testing uses current sweeping, the method is difficult and time-consuming, and when the input voltage or output voltage of the switching regulator changes, the above problems can occur again.

Summary of the Invention

Problems to be Solved by the Invention

[0010] In this context, an object of the present embodiment is, in one aspect, to provide a technique for improving the efficiency of a switching regulator through optimal zero-current switching. In another aspect, an object of the present embodiment is to provide a technique for removing an adjustment process for a zero-current detection reference value by mass production testing and shortening the manufacturing time for a switching regulator. In still another aspect, an object of the present embodiment is to provide a technique for adaptively setting a zero-current detection reference value even for changes in an input voltage, an output voltage, and an inductance.

Means for Solving the Problem

[0011] To achieve the above object, one embodiment includes a first switch block, a second switch block, a third switch block, and a fourth switch block connected in series to each other, a flying capacitor is connected to a first node where the first switch block and the second switch block are connected and a second node where the third switch block and the fourth switch block are connected, an inductor is connected to a third node where the second switch block and the third switch block are connected, a switch network, and a control circuit that compares a current value of one of the first switch block, the second switch block, the third switch block, and the fourth switch block with a zero-current detection reference value to control zero-current switching for the one switch block, and compares a voltage value at one end and a voltage value at the other end of the one switch block confirmed at a point in time after zero-current switching to adjust the zero-current detection reference value, and provides a switching regulator.

[0012] A certain time delay can exist between a time point when the current value of the one switch block is compared with the zero-current detection reference value and a time point when the one switch block is controlled for zero-current switching.

[0013] The control circuit can turn off only the third switch block by zero-current switching control with the first switch block and the third switch block turned on, compare the drain voltage value and the source voltage value of the third switch block after the third switch block is turned off, and adjust the detection reference value of the zero current.

[0014] When the drain voltage value of the third switch block after the third switch block is turned off is lower than the source voltage value, the control circuit determines that the third switch block is turned off with current flowing from the third switch block in the direction of the inductor. When the drain voltage value of the third switch block is higher than the source voltage value, the control circuit can determine that the third switch block is turned off with current flowing through the inductor in the direction of the third switch block.

[0015] The control circuit can increase or decrease the detection reference value of the zero current according to the direction of the current.

[0016] The control circuit can turn off only the fourth switch block by zero-current switching control with the second switch block and the fourth switch block turned on, compare the drain voltage value and the source voltage value of the fourth switch block after the fourth switch block is turned off, and adjust the detection reference value of the zero current.

[0017] The control circuit can control the switch network in a first state in which the first switch block and the second switch block are turned on, a second state in which the third switch block and the fourth switch block are turned on, a third state in which the first switch block and the third switch block are turned on, and a fourth state in which the second switch block and the fourth switch block are turned on, control such that the first state and the second state alternate, operate the switch network as a buck converter or a boost converter, control such that the third state and the fourth state alternate, and operate the switch network as a resonant converter.

[0018] The control circuit can end the third state or the fourth state through zero-current switching.

[0019] In one switch block, a transistor, a diode, and a parasitic capacitor can be formed in parallel.

[0020] Another embodiment provides a switching regulator including one switch disposed in a path through which an inductor current flows, and a control circuit that compares a current value of the one switch with a zero-current detection reference value to control zero-current switching for the one switch, compares a voltage value at one end of the one switch and a voltage value at the other end of the one switch confirmed at a point in time after zero-current switching, and adjusts the zero-current detection reference value.

[0021] A certain time delay can exist between a time point at which the current value of the one switch is compared with the zero-current detection reference value and a time point at which the one switch is controlled for zero-current switching.

[0022] The control circuit can adjust the zero-current detection reference value in a direction in which a difference between the voltage value at the one end of the one switch and the voltage value at the other end of the one switch decreases.

[0023] The drain of the one switch is electrically connected to the inductor, and the control circuit can compare the drain voltage value and the source voltage value of the one switch confirmed at a point in time after zero-current switching, and adjust the detection reference value of the zero current.

[0024] When the direction of current flowing from the one switch to the inductor is defined as the positive direction, when the drain voltage value confirmed at a point in time after zero-current switching is lower than the source voltage value, the control circuit determines that the one switch has been turned off in a state where the current flows in the positive direction, and when the drain voltage value is higher than the source voltage value, it can be determined that the one switch has been turned off in a state where the current flows in the negative direction.

[0025] The control circuit can increase or decrease the detection reference value of the zero current according to the direction of the current.

Advantages of the Invention

[0026] As described above, according to this embodiment, the efficiency of the switching regulator can be improved by optimal zero-current switching. And according to this embodiment, the adjustment process for the detection reference value of zero current in mass production testing can be removed, and the manufacturing time of the switching regulator can be shortened. And according to this embodiment, the detection reference value of zero current can also be adaptively set for changes in the input voltage, output voltage, and inductance in the switching regulator.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0028] Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. Note that when assigning reference numerals to the components of each drawing, the same components are assigned the same numerals as much as possible even if they are shown in different drawings. In the description of the present invention, if it is determined that a specific description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

[0029] In addition, when describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. can be used. Such terms are only for distinguishing the components from other components, and the essence, order, sequence, etc. of the components are not limited by such terms. When a component is described as "connected", "coupled", or "connected" to another component, it should be understood that the component can be directly connected or connected to the other component, but additional other components between the components may also be "connected", "coupled", or "connected".

[0030] FIG. 2 is a configuration diagram of a switching regulator according to an embodiment.

[0031] Referring to FIG. 2, the switching regulator 200 can include a switch network 210, a control circuit 220, and current sensors 231 to 234.

[0032] The switching regulator 200 has a first voltage V1, can convert the power input to the first node N1 to generate power having a second voltage V2, and output it to the sixth node N6. Alternatively, the switching regulator 200 has a second voltage V2, can convert the power input to the sixth node N6 to generate power having a first voltage V1, and output it to the first node N1.

[0033] The switch network 210 can include a first switch block, a second switch block, a third switch block, and a fourth switch block that are connected in series with each other.

[0034] Each switch block can include at least one switch. For example, the first switch block can include a first switch Q1, the second switch block can include a second switch Q2, the third switch block can include a third switch Q3, and the fourth switch block can include a fourth switch Q4. In the following, for the sake of convenience of explanation, an example in which each switch block includes one switch will be mainly described, but the present embodiment is not limited to this example.

[0035] In the following, the control of the first switch Q1 can be understood as the control of the first switch block, the control of the second switch Q2 can be understood as the control of the second switch block, the control of the third switch Q3 can be understood as the control of the third switch block, and the control of the fourth switch Q4 can be understood as the control of the fourth switch block. For example, turning off the first switch Q1 can be understood as turning off the first switch block, and turning on the second switch Q2 can be understood as turning on the second switch block.

[0036] The first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 may be power semiconductors. For example, the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 may be MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), may be IGBTs (Insulated Gate Bipolar Transistors), or may be other forms of power semiconductors. A transistor, a diode, and a parasitic capacitor can be formed in parallel in the first switch Q1, the second switch Q2, the third switch Q3, or the fourth switch Q4. The transistor, the diode, and the parasitic capacitor may be naturally formed by the characteristics of a power semiconductor such as a MOSFET, or may be formed by an additional configuration such as an inverse diode attached in parallel to an IGBT.

[0037] The first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 may be connected in series with each other. For example, the first switch Q1 and the second switch Q2 may be connected to each other through the second node N2, the second switch Q2 and the third switch Q3 may be connected to each other through the third node N3, and the third switch Q3 and the fourth switch Q4 may be connected to each other through the fourth node N4.

[0038] The first node N1 may be formed on one side of the first switch Q1, and the second node N2 may be formed on the other side, but the first voltage V1 may be supplied or output to the first node N1. And the fifth node N5 may be formed on one side of the fourth switch Q4, and the fourth node N4 may be formed on the other side, but a low voltage (for example, a ground voltage) may be supplied to the fifth node N5. The first voltage V1 supplied to the first node N1 may be a voltage relatively higher than the low voltage supplied to the fifth node N5. Thus, the voltage supplied to the first node N1 can be referred to as a high voltage, and the voltage supplied to the fifth node N5 can be referred to as a low voltage.

[0039] The switching network 210 may be connected to an inductor L and a flying capacitor C. FLY

[0040] The flying capacitor C FLY may have one side connected to a second node N2 to which the first switch Q1 and the second switch Q2 are connected, and the other side connected to a fourth node N4 to which the third switch Q3 and the fourth switch Q4 are connected.

[0041] The inductor L may have one side connected to a third node N3 to which the second switch Q2 and the third switch Q3 are connected, and the other side connected to a sixth node N6 at which a second voltage V2 is output.

[0042] Furthermore, an output capacitor C can be further disposed between the sixth node N6 and the low voltage.

[0043] The control circuit 220 can control the switches Q1 to Q4 included in the switching network 210. The control circuit 220 can set the switching network 210 to a plurality of states while turning on or off the switches Q1 to Q4.

[0044] The control circuit 220 can send gate signals to the gates of the switches Q1 to Q4 to turn on or off each of the switches Q1 to Q4.

[0045] The control circuit 220 can operate at least one of the switches Q1 to Q4 in a linear mode. When operating in the linear mode, the amount of current flowing through at least one switch can be limited to a certain level by the gate signal.

[0046] The control circuit 220 can sense the current, voltage, etc. of the switching network 210 or each of the nodes N1 to N6, and change the state of the switching network 210 using the sensed values.

[0047] ​ For example, the control circuit 220 can sense the first voltage V1, the second voltage V2, the flying capacitor voltage V CFLY , the third node voltage V SW , etc. And the control circuit 220 can sense the first switch current I Q1 , the second switch current I Q2 , the third switch current I Q3 , the fourth switch current I Q4 , etc.

[0048] And the control circuit 220 can determine or change the state of the switch network 210 by using at least one sensing value among the first voltage V1, the second voltage V2, the flying capacitor voltage V CFLY , the third node voltage V SW , the first switch current I Q1 , the second switch current I Q2 , the third switch current I Q3 , and the fourth switch current I Q4 .

[0049] It is possible to sense all of the above values, or only some of the values. For example, the control circuit 220 can sense only one of the first switch current I Q1 and the third switch current I Q3 , and can sense only one of the second switch current I Q2 and the fourth switch current I Q4 .

[0050] The control circuit 220 can control the switch network 210 in seven states described later.

[0051] And when the control circuit 220 switches the state, it can perform zero-current switching control. At this time, the control circuit 220 uses the voltage value at one end and the voltage value at the other end of each switch Q1~Q4 or each node voltage V N2 , V SW , VN4 , V N5 By adjusting the zero-current detection reference value by V, the zero current can be adaptively detected, and the efficiency of the switching regulator 200 can be improved.

[0052] FIG. 3 is a diagram showing a 0th state of a switch network according to an embodiment.

[0053] Referring to FIG. 3, the control circuit can turn off all the switches Q1 to Q4 of the switch network 210 and set the switch network 210 to the 0th state.

[0054] FIG. 4 is a diagram showing a 1st state of a switch network according to an embodiment.

[0055] Referring to FIG. 4, the control circuit can turn on the 1st switch Q1 and the 2nd switch Q2, turn off the 3rd switch Q3 and the 4th switch Q4, and set the switch network 210 to the 1st state.

[0056] In the 1st state, the flying capacitor C FLY is floated, and the flying capacitor voltage V CFLY can maintain a constant level.

[0057] Although the 1st voltage V1 (high voltage) can be supplied to one side of the 1st switch Q1, in the 1st state, when the 1st switch Q1 and the 2nd switch Q2 are turned on and the 3rd switch Q3 and the 4th switch Q4 are turned off, the 1st voltage V1 can be supplied to one side of the inductor L.

[0058] Although the 2nd voltage V2 can be supplied to the other side of the inductor L, thereby, in the 1st state, the 1st voltage V1 can be supplied to one side of the inductor L and the 2nd voltage V2 can be supplied to the other side. And with such voltages V1 and V2, the inductor current i in the 1st state LIt may be built up.

[0059] The first state may be the same as the operation in the buck converter or the boost converter.

[0060] FIG. 5 is a diagram showing a second state of the switch network according to an embodiment.

[0061] Referring to FIG. 5, the control circuit can turn off the first switch Q1 and the second switch Q2, turn on the third switch Q3 and the fourth switch Q4, and set the switch network 210 to the second state.

[0062] In the second state, the flying capacitor C FLY is floated, and the flying capacitor voltage V CFLY can maintain a constant level.

[0063] A ground voltage (low voltage) can be supplied to one side of the fourth switch Q4. However, in the second state, by turning off the first switch Q1 and the second switch Q2 and turning on the third switch Q3 and the fourth switch Q4, a ground voltage (low voltage) can be supplied to one side of the inductor L.

[0064] A second voltage V2 can be supplied to the other side of the inductor L. As a result, in the second state, a ground voltage (low voltage) can be supplied to one side of the inductor L and the second voltage V2 can be supplied to the other side. And with such a voltage, the inductor current i L may be built up.

[0065] The inductor current i L can build up in opposite directions in the first state and the second state. For example, in the first state, the inductor current i Lmay be built up in the increasing direction, and in the second state, the inductor current i L may be built up in the decreasing direction.

[0066] The second state may be the same as the operation in a buck converter or a boost converter.

[0067] FIG. 6 is a diagram showing a third state of a switch network according to an embodiment.

[0068] Referring to FIG. 6, the control circuit can turn on the first switch Q1 and the third switch Q3, turn off the second switch Q2 and the fourth switch Q4, and set the switch network 210 to the third state.

[0069] In the third state, the flying capacitor C FLY is connected in series with the inductor L, and the inductor current i L and the flying capacitor voltage V CFLY can form a resonance waveform.

[0070] In the third state, the inductor current i L can form a resonance waveform that increases and then decreases. With such a resonance waveform of the inductor current i L the control circuit can turn off or turn on each of the switches Q1 to Q4 at zero current.

[0071] The third state may be the same as the operation in a resonant converter.

[0072] FIG. 7 is a diagram showing a fourth state of a switch network according to an embodiment.

[0073] Referring to FIG. 7, the control circuit can turn off the first switch Q1 and the third switch Q3, turn on the second switch Q2 and the fourth switch Q4, and set the switch network 210 to the fourth state.

[0074] In the fourth state, the flying capacitor C FLY is connected in series with the inductor L, and the inductor current i L and the flying capacitor voltage V CFLY can form a resonance waveform.

[0075] In the fourth state, the inductor current i L can form a resonance waveform that increases and then decreases. Due to such a resonance waveform of the inductor current i L the control circuit can turn off or turn on each of the switches Q1 to Q4 at zero current.

[0076] The fourth state may be the same as the operation in the resonant converter.

[0077] FIG. 8 is a diagram showing the fifth state of the switch network according to an embodiment.

[0078] Referring to FIG. 8, the control circuit can turn on the first switch Q1 and the fourth switch Q4, turn off the second switch Q2 and the third switch Q3, and set the switch network 210 to the fifth state.

[0079] At initial startup or in an abnormal state, when the flying capacitor voltage V CFLY is lower than a preset voltage range or voltage level, the control circuit can set the switch network 210 to the fifth state.

[0080] In the fifth state, the first voltage V1, the first switch Q1, the flying capacitor C FLY, a current path is formed in series between the fourth switch Q4 and the ground voltage, and the flying capacitor C is charged by the current in such a current path. FLY can be charged.

[0081] In order to prevent excessive current (e.g., inrush current) from flowing through the first switch Q1 and / or the fourth switch Q4 in the fifth state, the control circuit can operate the first switch Q1 and the fourth switch Q4 in linear mode. At this time, the control circuit can sense the current flowing through the first switch Q1 and the fourth switch Q4 and control the first switch Q1 and the fourth switch Q4 according to the sensing value.

[0082] FIG. 9 is a diagram showing the sixth state of a switch network according to an embodiment.

[0083] Referring to FIG. 9, the control circuit can turn off the first switch Q1 and the fourth switch Q4, turn on the second switch Q2 and the third switch Q3, and set the switch network 210 to the sixth state.

[0084] In an abnormal state, when the flying capacitor voltage V CFLY is higher than a preset voltage range or voltage level, the control circuit can control the switch network 210 to the sixth state.

[0085] In the sixth state, the second switch Q2 and the third switch Q3 can be arranged in parallel with the flying capacitor C FLY And the flying capacitor C can be discharged through such second switch Q2 and third switch Q3 FLY can be discharged.

[0086] In the sixth state, in order to prevent excessive current from flowing through the second switch Q2 and / or the third switch Q3, the control circuit can operate the second switch Q2 and the third switch Q3 in the linear mode. At this time, the control circuit can control the second switch Q2 and the third switch Q3 according to the sensing value while sensing the current flowing through the second switch Q2 and the third switch Q3.

[0087] The control circuit can control the switch network so that the third state and the fourth state alternate.

[0088] A switching regulator according to an embodiment can transfer power through the resonance of a flying capacitor and an inductor.

[0089] The control circuit can drive the third state and the fourth state at the resonance frequency of the flying capacitor and the inductor or a frequency close thereto. In this case, power can be transferred through the resonance of the flying capacitor and the inductor like a resonant converter.

[0090] The third state and the fourth state can be controlled to alternate. For example, the switch network can operate in the fourth state after operating in the third state and operate in the third state after operating in the fourth state.

[0091] When pulse - shaping refers to forming one increase / decrease waveform while the inductor current increases and then decreases, one pulse - shaping can be performed in each of the third state and the fourth state.

[0092] FIG. 10 is a diagram showing pulse - shaping the inductor current using the third state and the fourth state in one embodiment.

[0093] Referring to FIG. 10, the control circuit can control the switch network so that the third state and the fourth state alternate.

[0094] And when the inductor current i L reaches the zero current level, the third state or the fourth state can be terminated.

[0095] In the third state, the flying capacitor can be charged and the flying capacitor voltage V CFLY can increase. And the inductor current i L can increase and then decrease. The control circuit, in the third state, when the inductor current i L reaches the zero current level (a level within a preset error range of zero), can terminate the third state while forming the end of the pulse shaping.

[0096] In the fourth state, the flying capacitor is discharged and the flying capacitor voltage V CFLY can decrease. And the inductor current i L can increase and then decrease. The control circuit, in the fourth state, when the inductor current i L reaches the zero current level (a level within a preset error range of zero), can terminate the fourth state while forming the end of the pulse shaping.

[0097] To more accurately form such pulse shaping, the control circuit can adaptively detect the zero current and control the switch network based on it.

[0098] The control circuit can control zero-current switching for the switch by comparing the current value of the switch with a zero-current detection reference value. However, the control circuit can more accurately control zero-current switching by adjusting the zero-current detection reference value according to the characteristics of the switch network. Here, zero-current switching control is a concept that includes both zero-current turn-off control and zero-current turn-on control. In the following, for the sake of convenience of explanation, an example of zero-current turn-off control will be mainly described.

[0099] The control circuit can adjust the zero-current detection reference value according to the current direction during zero-current switching. For the purpose of explaining such an example, the direction of the current flowing from one side of the inductor to the other side (the direction of the current flowing from the third node (see N3 in FIG. 2) to the sixth node (see N6 in FIG. 2)) is defined as the positive direction.

[0100] FIG. 11 is a diagram showing the main waveforms when turning off the third switch in a state where current flows in the positive direction in one embodiment, and FIG. 12 is a diagram showing the main waveforms when turning off the third switch in a state where current flows in the negative direction in one embodiment.

[0101] Referring to FIGS. 11 and 12, the control circuit can turn off the third switch Q3 at the third time point T3. Although not shown in the figure, the control circuit can compare the current value of the third switch Q3 with the zero-current detection reference value at a time point earlier than the third time point T3 to control the zero-current switching (here, turn-off) of the third switch Q3. Then, the third switch Q3 can be substantially turned off at the third time point T3.

[0102] Referring to FIG. 11, at a time point T4 after zero-current switching, the drain voltage V of the third switch Q3 SW can be shown as a voltage V lower than the source voltage V N4 -Vd, and this waveform can be shown when the current is formed in the positive direction. Here, Vd is the drain voltage V N4 ​SW and the source voltage V N4 and may be the same as the forward voltage drop of the diode of the third switch Q3.

[0103] Referring to FIG. 12, at a point in time T4 after zero-current switching, the drain voltage V of the third switch Q3 SW is a voltage V higher than the source voltage V N4 +Vd can be shown, but this waveform can be shown when the current is formed in the negative direction. Here, Vd is the drain voltage V N4 and the source voltage V SW and may be the same as the voltage formed across the parasitic capacitor of the third switch Q3. N4 and may be the same as the voltage formed across the parasitic capacitor of the third switch Q3.

[0104] The control circuit can compare the drain voltage value and the source voltage value to determine the direction of the current, and increase or decrease the zero-current detection reference value according to the direction of the current. When the zero-current detection reference value is high, when the current flows in the positive direction, zero-current switching control is likely to be performed. When the zero-current detection reference value is low, when the current flows in the negative direction, zero-current switching control is likely to be performed. Thereby, when the direction of the current confirmed through the drain voltage value and the source voltage value is the positive direction, the control circuit can decrease the zero-current detection reference value, and when it is the negative direction, increase the zero-current detection reference value. Alternatively, the control circuit can increase or decrease the zero-current detection reference value in the direction in which the drain voltage value and the source voltage value decrease.

[0105] FIG. 13 is a diagram showing the main waveforms when turning off the fourth switch in a state where current flows in the positive direction in one embodiment, and FIG. 14 is a diagram showing the main waveforms when turning off the third switch in a state where current flows in the negative direction in one embodiment.

[0106] Referring to FIGS. 13 and 14, the control circuit can turn off the fourth switch Q4 at the fifth time point T5. Although not shown in the figure, the control circuit can compare the current value of the fourth switch Q4 with a zero-current detection reference value at a time point earlier than the fifth time point T5 to control the zero-current switching (here, turn-off) of the fourth switch Q4. And the fourth switch Q4 can be substantially turned off at the fifth time point T5.

[0107] Referring to FIG. 13, at a time point T6 after zero-current switching, the drain voltage V of the fourth switch Q4 N4 can be a voltage V lower than the source voltage V N5 -Vd, and this waveform can be shown when the current is formed in the positive direction. Here, Vd is the voltage difference between the drain voltage V N5 and the source voltage V, and may be the same as the forward voltage drop of the diode of the fourth switch Q4. N4 and the source voltage V N5 and may be the same as the forward voltage drop of the diode of the fourth switch Q4.

[0108] Referring to FIG. 14, at a time point T6 after zero-current switching, the drain voltage V of the fourth switch Q4 N4 can be a voltage V higher than the source voltage V N5 +Vd, and this waveform can be shown when the current is formed in the negative direction. Here, Vd is the voltage difference between the drain voltage V N5 and the source voltage V, and may be the same as the voltage formed across the parasitic capacitor of the fourth switch Q4. N4 and the source voltage V N5 and may be the same as the voltage formed across the parasitic capacitor of the fourth switch Q4.

[0109] The control circuit can compare the drain voltage value and the source voltage value to determine the direction of the current, and increase or decrease the zero-current detection reference value according to the direction of the current. When the zero-current detection reference value is high, when the current flows in the positive direction, zero-current switching control is likely to be performed. When the zero-current detection reference value is low, when the current flows in the negative direction, zero-current switching control is likely to be performed. Thereby, when the direction of the current confirmed through the drain voltage value and the source voltage value is the positive direction, the control circuit can decrease the zero-current detection reference value, and when it is the negative direction, increase the zero-current detection reference value. Alternatively, the control circuit can increase or decrease the zero-current detection reference value in the direction in which the drain voltage value and the source voltage value decrease.

[0110] The adjustment of the zero-current detection reference value can be performed periodically or aperiodically. For example, the control circuit can adjust the zero-current detection reference value once per switching period, or once per N (N is a natural number greater than or equal to 2) switching periods.

[0111] As described above, according to this embodiment, the efficiency of the switching regulator can be improved by optimal zero-current switching. And according to this embodiment, the adjustment process for the zero-current detection reference value in mass production testing can be removed, and the manufacturing time of the switching regulator can be shortened. And according to this embodiment, the zero-current detection reference value can also be adaptively set according to changes in the input voltage, output voltage, and inductance in the switching regulator.

[0112] As described above, terms such as "including", "comprising", or "having" mean that the corresponding component can be inherent therein, unless otherwise stated, and do not exclude other components, but should be construed as being able to further include other components. All terms, including technical or scientific terms, shall have the same meaning as generally understood by those having ordinary knowledge in the technical field to which the present invention pertains, unless otherwise defined. Commonly used terms, such as pre-defined terms, should be construed as being consistent with their meaning in the context of the related art, and should not be construed as having an ideal or overly formal meaning, unless clearly defined in the present invention.

[0113] The above description merely exemplarily explains the technical idea of the present invention. Those having ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are for the purpose of explaining rather than limiting the technical idea of the present invention, and the scope of the technical idea of the present invention is not limited by such embodiments. The protection scope of the present invention should be construed according to the following claims, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

Claims

1. A switching network including a first switch block, a second switch block, a third switch block, and a fourth switch block connected in series with each other, a flying capacitor being connected to a first node where the first switch block and the second switch block are connected and a second node where the third switch block and the fourth switch block are connected, and an inductor being connected to a third node where the second switch block and the third switch block are connected, and a control circuit that compares a current value of one of the first switch block, the second switch block, the third switch block, and the fourth switch block with a zero-current detection reference value to control zero-current switching for the one switch block, compares a voltage value at one end and a voltage value at the other end of the one switch block confirmed at a point in time after zero-current switching, and adjusts the zero-current detection reference value. A switching regulator.

2. The switching regulator according to claim 1, wherein there is a certain time delay between a time point when the current value of the one switch block is compared with the zero-current detection reference value and a time point when the one switch block is controlled for zero-current switching.

3. The control circuit is in a state where the first switch block and the third switch block are turned on, only the third switch block is turned off by zero-current switching control, and after the third switch block is turned off, a drain voltage value and a source voltage value of the third switch block are compared to adjust the zero-current detection reference value. The switching regulator according to claim 1.

4. The control circuit is when the drain voltage value of the third switch block after the third switch block is turned off is lower than the source voltage value, it is determined that the third switch block is turned off with current flowing from the third switch block in the direction of the inductor, and when the drain voltage value of the third switch block is higher than the source voltage value, it is determined that the third switch block is turned off with current flowing through the inductor in the direction of the third switch block. The switching regulator according to claim 3.

5. The control circuit is a switching regulator according to claim 4, which increases or decreases the detection reference value of the zero current according to the direction of the current.

6. The control circuit is a switching regulator according to claim 1, which turns off only the fourth switch block by zero current switching control in a state where the second switch block and the fourth switch block are turned on, compares the drain voltage value and the source voltage value of the fourth switch block after the fourth switch block is turned off, and adjusts the detection reference value of the zero current.

7. The control circuit can control the switch network in a first state in which the first switch block and the second switch block are turned on, a second state in which the third switch block and the fourth switch block are turned on, a third state in which the first switch block and the third switch block are turned on, and a fourth state in which the second switch block and the fourth switch block are turned on, controls the first state and the second state to alternate, can operate the switch network as a buck converter or a boost converter, controls the third state and the fourth state to alternate, and can operate the switch network as a resonant converter, which is a switching regulator according to claim 1.

8. The control circuit is a switching regulator according to claim 7, which ends the third state or the fourth state through zero current switching.

9. In the one switch block, a transistor, a diode, and a parasitic capacitor are formed in parallel, which is a switching regulator according to claim 1.

10. One switch arranged in a path through which an inductor current flows, and a control circuit that compares the current value of the one switch with a detection reference value of zero current to control zero current switching for the one switch, compares the voltage value at one end and the voltage value at the other end of the one switch confirmed at a moment after zero current switching, and adjusts the detection reference value of the zero current, including a switching regulator.

11. The switching regulator according to claim 10, wherein there is a certain time delay between the time when the current value of the one switch is compared with the detection reference value of zero current and the time when the one switch is controlled by zero current switching.

12. The control circuit adjusts the detection reference value of zero current in a direction in which the difference between the voltage value at one end and the voltage value at the other end of the one switch decreases. The switching regulator according to claim 10.

13. The drain of the one switch is electrically connected to the inductor, The control circuit compares the drain voltage value and the source voltage value of the one switch confirmed at a point in time after zero current switching, and adjusts the detection reference value of zero current. The switching regulator according to claim 10.

14. When the direction of the current flowing from the one switch to the inductor is defined as the positive direction, The control circuit When the drain voltage value confirmed at a point in time after zero current switching is lower than the source voltage value, it is determined that the one switch has been turned off in a state where the current flows in the positive direction. When the drain voltage value is higher than the source voltage value, it is determined that the one switch has been turned off in a state where the current flows in the negative direction. The switching regulator according to claim 13.

15. The control circuit increases or decreases the detection reference value of zero current according to the direction of the current. The switching regulator according to claim 14.

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