Switching regulator capable of adaptively detecting zero current and control method thereof

Abstract

An embodiment provides a switching regulator, comprising: a switching network comprising a first switching block, a second switching block, a third switching block and a fourth switching block which are connected in series, a flying capacitor is connected to a first node connected with the first switch block and the second switch block and a second node connected with the third switch block and the fourth switch block, and an inductor is connected to a third node connected with the second switch block and the third switch block; and a control circuit which 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 of the one switch block, and comparing the voltage value at one end of the switch block and the voltage value at the other end of the switch block confirmed at a time point after zero current switching so as to adjust the zero current detection reference value.

Description

Technical Field

[0001] This embodiment relates to a switching regulator. Background Art

[0002] Switching regulators are important components in electronic devices that can effectively perform power conversion and voltage control to maintain the stability and efficiency of electronic devices. However, when the switch is turned on or off in a switching regulator, switching loss is inevitably generated, and sometimes noise including electromagnetic waves is generated.

[0003] In order to solve this problem and improve the performance of the switching regulator, the switching regulator can usually adopt a method of detecting and controlling zero current. By turning on or off the switch in the zero current state, the switching regulator can minimize unnecessary energy loss and ensure reliable operation. However, there may be a time difference between the time point when the zero current is detected and the time point when the switch switches to zero current. This may be caused by circuit structure, switch operation delay, etc. Due to the existence of this time difference, the problem cannot be perfectly solved.

[0004] Figure 1 FIG. 1 is a schematic diagram for explaining the problem that zero current switching cannot be perfectly achieved in a switching regulator according to the prior art.

[0005] See also Figure 1 , the switching regulator may compare the switch current value with the zero current detection reference value at a first time point T1, and then, the switching regulator may cut off the switch at a second time point T2 according to the comparison result.

[0006] There may be a certain time delay between the first time point T1 and the second time point T2. The time delay may occur in the process of comparing the switch current value with the zero current detection reference value, or in the switch control operation of cutting off the switch by supplying a gate signal to the switch.

[0007] Since there is a time delay between the time point T1 of comparing the switching current value and the zero current detection reference value and the time point T2 of cutting off the switch, the switching regulator can set the absolute value of the zero current detection reference value to a value greater than 0 (A) as the actual value. Figure 1 In the case of the first current curve 10, the switching regulator sets the zero current detection reference value to be higher than 0 (A), according to which, at the second time point T2, the switch is cut off when the current value (current value 1) actually becomes 0 (A).

[0008] But in Figure 1In the case of the first current curve 11, even if the switching regulator sets the zero current detection reference value to be the same as in the above example, due to the different slopes of the switch current values, at time point T2, the switch is turned off when the current value (current value 2) of the switch is lower than 0 (A). As described above, when the current value of the switch is lower or higher than 0 (A) at the time point when the switch is turned off, zero current switching cannot be perfectly achieved, which reduces the effect of reducing switching loss and noise.

[0009] During the mass production of switching regulators, the zero current detection reference value can be adjusted before shipment through testing. However, since this test utilizes current sweep frequency, it is cumbersome and time-consuming. Furthermore, if the input voltage or output voltage of the switching regulator changes, the aforementioned problem may occur again. Summary of the invention

[0010] Problem that the invention aims to solve

[0011] In this context, on the one hand, the purpose of this embodiment is to provide a technology for improving the efficiency of a switching regulator by optimizing zero current switching. On the other hand, the purpose of this embodiment is to provide a technology for eliminating the process of adjusting the zero current detection reference value through mass production testing, thereby shortening the manufacturing time of the switching regulator. On the other hand, the purpose of this embodiment is to provide a technology for adaptively setting the zero current detection reference value even if the input voltage, output voltage and inductance change.

[0012] Solutions to the problem

[0013] To achieve the objective, an embodiment provides a switching regulator, comprising: a switching network, comprising a first switch block, a second switch block, a third switch block and a fourth switch block connected in series, a flying capacitor connected to a first node connected to the first switch block and the second switch block and a second node connected to the third switch block and the fourth switch block, and an inductor connected to a third node connected to the second switch block and the third switch block; and a control circuit, comparing a current value of a switch block among 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 of the switch block, and comparing a voltage value at one end of the switch block and a voltage value at the other end confirmed at a time point after the zero current switching to adjust the zero current detection reference value.

[0014] There is a fixed time delay between the time point at which the current value of a switching block is compared with the zero current detection reference value and the time point at which the switching block is controlled to switch to zero current.

[0015] When the first switch block and the third switch block are turned on, the control circuit only cuts off the third switch block according to zero current switching control, and compares the drain voltage value and the source voltage value of the third switch block after the third switch block is cut off to adjust the zero current detection reference value.

[0016] The control circuit determines that the third switch block is cut off when the drain voltage value of the third switch block after the third switch block is cut off is lower than the source voltage value, while the control circuit determines that the third switch block is cut off when the current flows from the inductor to the third switch block when the drain voltage value of the third switch block is higher than the source voltage value.

[0017] The control circuit increases or decreases the zero current detection reference value according to the direction of the current.

[0018] When the second switch block and the fourth switch block are turned on, the control current only cuts off the fourth switch block according to the zero current switching control, and compares the drain voltage value and the source voltage value of the fourth switch block after the fourth switch block is cut off to adjust the zero current detection reference value.

[0019] The control circuit can control the switch network through the following states: 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 the first state and the second state to alternate so that the switch network operates as a buck converter or a boost converter; control the third state and the four states to alternate so that the switch network operates as a resonant converter.

[0020] The control circuit ends the third state or the fourth state through zero current switching.

[0021] A transistor, a diode and a parasitic capacitor are formed in parallel on the switch block.

[0022] Another embodiment provides a switching regulator, comprising: a switch, provided in a path through which an inductor current flows; and a control circuit, which compares the current value of the switch with a zero current detection reference value to control the zero current switching of the switch, and compares the voltage value of one end of the switch and the voltage value of the other end of the switch confirmed at a time point after the zero current switching to adjust the zero current detection reference value.

[0023] There is a fixed time delay between the time point at which the current value of a switch is compared with the zero current detection reference value and the time point at which the switch is controlled to switch to zero current.

[0024] The control circuit adjusts the zero current detection reference value according to a decreasing trend of a difference between a voltage value at one end and a voltage value at another end of the switch.

[0025] The drain of the switch is electrically connected to the inductor; the control circuit compares the drain voltage value and the source voltage value of the switch confirmed at a time point after zero current switching to adjust the zero current detection reference value.

[0026] When the direction of current flowing from the switch to the inductor is defined as a forward direction, when the drain voltage value confirmed by the control circuit at a time point after the zero current switching is lower than the source voltage value, it is determined that the switch is cut off when the current flows in the forward direction; when the drain voltage value is higher than the source voltage value, it is determined that the switch is cut off when the current flows in the negative direction.

[0027] The control circuit increases or decreases the zero current detection reference value according to the direction of the current.

[0028] Effects of the Invention

[0029] As described above, according to the present embodiment, the efficiency of the switching regulator can be improved by optimal zero current switching. In addition, according to the present embodiment, the process of adjusting the zero current detection reference value through mass production testing is eliminated, thereby shortening the manufacturing time of the switching regulator. In addition, according to the present embodiment, even if the input voltage, output voltage and inductance change in the switching regulator, the zero current detection reference value can be adaptively set.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 FIG. 1 is a schematic diagram for explaining the problem that zero current switching cannot be perfectly achieved in a switching regulator according to the prior art.

[0032] Figure 2 FIG. 4 is a structural diagram of a switching regulator according to an embodiment.

[0033] Figure 3 FIG. 4 is a schematic diagram of a 0th state of a switch network according to an embodiment.

[0034] Figure 4 is a schematic diagram of a first state of a switch network according to an embodiment.

[0035] Figure 5 is a schematic diagram of a second state of a switch network according to an embodiment.

[0036] Figure 6 is a schematic diagram of a third state of a switch network according to an embodiment.

[0037] Figure 7 is a schematic diagram of a fourth state of a switch network according to an embodiment.

[0038] Figure 8 is a schematic diagram of a fifth state of a switch network according to an embodiment.

[0039] Fig. 9 is a schematic diagram of a sixth state of a switch network according to an embodiment.

[0040] Fig.10 FIG. 4 is a schematic diagram of performing pulse shaping on the inductor current by utilizing the third state and the fourth state in one embodiment.

[0041] Fig.11 FIG. 4 is a schematic diagram of main waveforms when the third switch is turned off when the current flows in the forward direction in one embodiment.

[0042] Fig.12 FIG. 4 is a schematic diagram of main waveforms when the third switch is turned off when the current flows in the negative direction in one embodiment.

[0043] Fig.13 FIG. 4 is a schematic diagram of main waveforms when the fourth switch is turned off when the current flows in the forward direction in one embodiment.

[0044] Fig.14 FIG. 4 is a schematic diagram of main waveforms when the fourth switch is turned off when the current flows in the negative direction in one embodiment. DETAILED DESCRIPTION

[0045] Below, some embodiments of the present invention are described in detail with reference to the exemplary drawings. It should be noted that when assigning marks to the structures in the drawings, the same marks are assigned to the same structures as much as possible even in different drawings. In addition, in the process of describing the present invention in detail, if it is considered that the specific description of the relevant disclosed function or structure hinders the understanding of the present invention, its detailed description will be omitted.

[0046] In addition, when describing the constituent elements of the present invention, terms such as first, second, A, B, (a), (b) and the like may be used. The terms are only used to distinguish one component from another component, and the nature or order of the corresponding components is not limited by the terms. When it is described that a component is "connected", "combined" or "coupled" to another component, the component may be directly connected or coupled to the other component, but other components may also be "connected", "combined" or "coupled" between the components.

[0047] Figure 2FIG. 4 is a structural diagram of a switching regulator according to an embodiment.

[0048] See also Figure 2 The switching regulator 200 may include a switch network 210 , a control circuit 220 , and current sensors 231 ˜ 234 .

[0049] The switching regulator 200 converts power input to the first node N1 with the first voltage V1 to generate power of the second voltage V2 and outputs it to the sixth node N6. Alternatively, the switching regulator 200 converts power input to the sixth node N6 with the second voltage V2 to generate power of the first voltage V1 and outputs it to the first node N1.

[0050] The switch network 210 includes a first switch block, a second switch block, a third switch block, and a fourth switch block connected in series.

[0051] Each switch block may include at least one switch. For example, the first switch block may include a first switch Q1, the second switch block may include a second switch Q2, the third switch block may include a third switch Q3, and the fourth switch block may include a switch Q4. For ease of description, the following description is based on an example in which each switch block includes one switch, but the present embodiment is not limited thereto.

[0052] In the following, control of the first switch Q1 can be understood as control of the first switch block, control of the second switch Q2 can be understood as control of the second switch block, control of the third switch Q3 can be understood as control of the third switch block, and control of the fourth switch Q4 can be understood as 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 off the second switch Q2 can be understood as turning off the second switch block.

[0053] 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 metal oxide semiconductor field effect transistors (MOSFET), insulated gate bipolar transistors (IGBT) or other types of power semiconductors. Transistors, diodes and parasitic capacitors may be formed in parallel on the first switch Q1, the second switch Q2, the third switch Q3 or the fourth switch Q4. Transistors, diodes and parasitic capacitors may be formed naturally according to the properties of power semiconductors, such as MOSFET, etc., or may be formed by additional structures, such as a reverse diode attached in parallel to an IGBT, etc.

[0054] The first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 may be connected in series. For example, the first switch Q1 and the second switch Q2 may be connected to each other via the second node N2, the second switch Q2 and the third switch Q3 may be connected to each other via the third node N3, and the third switch Q3 and the fourth switch Q4 may be connected to each other via the fourth node N4.

[0055] A first node N1 may be formed on one side of the first switch Q1, a second node N2 may be formed on the other side, and a first voltage V1 may be supplied or output to the first node N1. In addition, a fifth node N5 may be formed on one side of the fourth switch Q4, a fourth node N4 may be formed on the other side, and a low voltage, such as a ground voltage, may be supplied to the fifth node N5. The first voltage V1 supplied to the first node N1 may be relatively higher than the low voltage supplied to the fifth node N5. Therefore, the voltage supplied to the first node N1 may be referred to as a high voltage, and the voltage supplied to the fifth node N5 may be referred to as a low voltage.

[0056] The switch network 210 may be connected to an inductor L and a flying capacitor C FLY .

[0057] Flying capacitor C FLY One side of the transistor is connected to a second node N2 connected to the first switch Q1 and the second switch Q2, and the other side of the transistor is connected to a fourth node N4 connected to the third switch Q3 and the fourth switch Q4.

[0058] One side of the inductor L is connected to a third node N3 connected to the second switch Q2 and the third switch Q3 , and the other side of the inductor L is connected to a sixth node N6 outputting the second voltage V2 .

[0059] Furthermore, an output capacitor C may be provided between the sixth node N6 and the low voltage.

[0060] The control circuit 220 can control the switches Q1-Q4 included in the switch network 210. The control circuit 220 can put the switch network 210 in various states by turning on or off the switches Q1-Q4.

[0061] The control circuit 220 may turn on or off each switch Q1 - Q4 by sending a gate signal to the gate of each switch Q1 - Q4 .

[0062] The control circuit 220 may operate at least one of the switches Q1-Q4 in a linear mode. When operating in the linear mode, a current flowing through the at least one switch may be limited to a fixed level according to a gate signal.

[0063] The control circuit 220 may sense the current, voltage, etc. of the switch network 210 or each node N1 - N6 , and change the state of the switch network 210 using the sensed value.

[0064] 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 In addition, 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 wait.

[0065] In addition, the control circuit 220 can utilize 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 , the fourth switch current I Q4 At least one sensed value in determines or changes the state of the switch network 210.

[0066] All of the values ​​may be sensed, or only some of the values ​​may be sensed. For example, the control circuit 220 may only sense the first switch current I Q1 and the third switch current I Q3 One of the switch currents I Q2 and the fourth switch current I Q4 one of the.

[0067] The control circuit 220 can control the switch network 210 to seven states which will be described later.

[0068] In addition, the control circuit 220 can perform zero current switching control when in the switching state. At this time, the control circuit 220 can control the switching state according to the voltage value of one end and the voltage value of the other end of each switch Q1-Q4 or the voltage V of each node in the switch network 210. N2 、V SW 、V N4 、V N5 The zero current detection reference value is adjusted to adaptively detect the zero current, thereby improving the efficiency of the switching regulator 200 .

[0069] Figure 3 is a schematic diagram of a 0th state of a switch network according to an embodiment;

[0070] See also Figure 3 , the control circuit can cut off all switches Q1-Q4 of the switch network 210 to put the switch network 210 in the 0th state.

[0071] Figure 4 is a schematic diagram of a first state of a switch network according to an embodiment.

[0072] See also Figure 4 , the control circuit can turn on the first switch Q1 and the second switch Q2, and turn off the third switch Q3 and the fourth switch Q4, so that the switch network 210 is in the first state.

[0073] In the first state, the flying capacitor C FLY In floating state, the flying capacitor voltage V CFLY A fixed level can be maintained.

[0074] A first voltage V1 (high voltage) may be supplied to one side of the first switch Q1 . In a first state, the first and second switches Q1 and Q2 are turned on, and the third and fourth switches Q3 and Q4 are turned off, so that the first voltage V1 is supplied to one side of the inductor L.

[0075] A second voltage V2 may be supplied to the other side of the inductor L. Therefore, in the first state, the first voltage V1 may be supplied to one side of the inductor L, and the second voltage V2 may be supplied to the other side. In addition, in the first state, the inductor current i L .

[0076] The first state may be the same as operation in a buck converter or a boost converter.

[0077] Figure 5 is a schematic diagram of a second state of a switch network according to an embodiment.

[0078] See also Figure 5 , the control circuit may turn off the first switch Q1 and the second switch Q2 and turn on the third switch Q3 and the fourth switch Q4 to put the switch network 210 in the second state.

[0079] In the second state, the flying capacitor C FLY In floating state, the flying capacitor voltage V CFLY A fixed level can be maintained.

[0080] The ground voltage (low voltage) may be supplied to one side of the fourth switch Q4. In the second state, the first switch Q1 and the second switch Q2 are turned off, and the third switch Q3 and the fourth switch Q4 are turned on, so that the ground voltage (low voltage) is supplied to one side of the inductor L.

[0081] A second voltage V2 may be supplied to the other side of the inductor L. Therefore, in the second state, a ground voltage (low voltage) may be supplied to one side of the inductor L, and the second voltage V2 may be supplied to the other side. In addition, in the second state, the inductor current i L .

[0082] In the first state and the second state, the inductor current i LFor example, when the direction of the current flowing from one side of the inductor L to the other side is defined as the forward direction, in the first state, the inductor current i L can be formed in the direction of increase, and in the second state, the inductor current i L Can be formed in a decreasing direction.

[0083] The second state may be identical to operation in a buck converter or a boost converter.

[0084] Figure 6 is a schematic diagram of a third state of a switch network according to an embodiment.

[0085] See also Figure 6 , the control circuit can turn on the first switch Q1 and the third switch Q3, and turn off the second switch Q2 and the fourth switch Q4, so that the switch network 210 is in the third state.

[0086] In the third state, the flying capacitor C FLY and inductor L in series so that the inductor current i L and the flying capacitor voltage V CFLY A resonant waveform can be formed.

[0087] In the third state, the inductor current i L A resonant waveform that increases first and then decreases can be formed. L The control circuit can cut off or turn on each switch Q1~Q4 from zero current according to the resonant waveform.

[0088] The third state may be identical to operation in a resonant converter.

[0089] Figure 7 is a schematic diagram of a fourth state of a switch network according to an embodiment.

[0090] See also Figure 7 , the control circuit may cut off the first switch Q1 and the third switch Q3 , and turn on the second switch Q2 and the fourth switch Q4 , so that the switch network 210 is in the fourth state.

[0091] In the fourth state, the flying capacitor C FLY and inductor L in series so that the inductor current i L and the flying capacitor voltage V CFLY A resonant waveform can be formed.

[0092] In the fourth state, the inductor current i L A resonant waveform that increases first and then decreases can be formed. L The control circuit can cut off or turn on each switch Q1~Q4 from zero current according to the resonant waveform.

[0093] The fourth state may be identical to operation in a resonant converter.

[0094] Figure 8 is a schematic diagram of a fifth state of a switch network according to an embodiment.

[0095] See also Figure 8 , the control circuit may turn on the first switch Q1 and the fourth switch Q4 , and turn off the second switch Q2 and the third switch Q3 , so that the switch network 210 is in the fifth state.

[0096] At initial startup or in abnormal conditions, when the flying capacitor voltage V CFLY When the voltage is lower than a preset voltage range or voltage level, the control circuit may control the switch network 210 to be in the fifth state.

[0097] In the fifth state, the first voltage V1, the first switch Q1, and the flying capacitor C FLY , the fourth switch Q4 and the ground voltage are connected in series to form a current path, the flying capacitor C FLY Charging can be performed by the current in this current path.

[0098] In the fifth state, in order to prevent excessive current (e.g., surge current) from flowing to the first switch Q1 and / or the fourth switch Q4, the control circuit may operate the first switch Q1 and / or the fourth switch Q4 in a linear mode. At this time, the control circuit may sense the current flowing to the first switch Q1 and / or the fourth switch Q4, and control the first switch Q1 and / or the fourth switch Q4 according to the sensed value.

[0099] Fig. 9 is a schematic diagram of a sixth state of a switch network according to an embodiment.

[0100] See also Fig. 9 , the control circuit may cut off the first switch Q1 and the fourth switch Q4 , and turn on the second switch Q2 and the third switch Q3 , so that the switch network 210 is in the sixth state.

[0101] Under abnormal conditions, when the flying capacitor voltage V CFLY When the voltage is higher than a preset voltage range or voltage level, the control circuit may control the switch network 210 to be in a sixth state.

[0102] In the sixth state, the second switch Q2 and the third switch Q3 can be connected to the flying capacitor C FLY In addition, the flying capacitor C can be connected to the flying capacitor C by the second switch Q2 and the third switch Q3. FLY Discharge.

[0103] In the sixth state, in order to prevent excessive current from flowing to the second switch Q2 and / or the third switch Q3, the control circuit can operate the second switch Q2 and / or the third switch Q3 in a linear mode. At this time, the control circuit can sense the current flowing to the second switch Q2 and / or the third switch Q3, and control the second switch Q2 and / or the third switch Q3 according to the sensed value.

[0104] The control circuit may control the switch network to alternate between the third state and the fourth state.

[0105] According to an embodiment, a switching regulator may transfer power through resonance of a flying capacitor and an inductor.

[0106] The control circuit can drive the third state and the fourth state at a resonant frequency of the flying capacitor and the inductor or a frequency close to the resonant frequency, so that power can be transferred through the resonance of the flying capacitor and the inductor like a resonant converter.

[0107] The third state and the fourth state may be controlled to alternate. For example, the switch network may operate in the fourth state after operating in the third state, or may operate in the third state after operating in the fourth state.

[0108] When the inductor current increases first and then decreases to form an increase / decrease waveform, which is called pulse-shaping, pulse-shaping can be completed once in the third state and the fourth state.

[0109] Fig.10 FIG. 4 is a schematic diagram of performing pulse shaping on the inductor current by utilizing the third state and the fourth state in one embodiment.

[0110] See also Fig.10 , the control circuit can control the switch network to alternate between the third state and the fourth state.

[0111] In addition, the inductor current i L When the zero current level is reached, the control circuit may end the third state or the fourth state.

[0112] In the third state, the flying capacitor can be charged, and the flying capacitor voltage V CFLY can be increased. In addition, the inductor current i L It can increase first and then decrease. In the third state, when the current i L When the zero current level is reached (reaching within a preset error range from 0), the control circuit can simultaneously end the third state and form the end of the pulse shaping.

[0113] In the fourth state, the flying capacitor can be discharged, and the flying capacitor voltage V CFLY can be reduced. In addition, the inductor current i L It can increase first and then decrease. In the fourth state, when the current i LWhen the zero current level is reached (reaching within a preset error range from 0), the control circuit can simultaneously end the fourth state and form the end of the pulse shaping.

[0114] In order to more accurately shape the pulse, the control circuit can adaptively detect zero current and control the switching network accordingly.

[0115] The control circuit can control the zero current switching of the switch by comparing the current value of the switch with the zero current detection reference value. The control circuit can adjust the zero current detection reference value according to the characteristics of the switch network, thereby controlling the zero current switching more accurately. Among them, the zero current switching control includes the concepts of zero current cut-off control and zero current connection control. For the convenience of description, the following mainly takes the zero current cut-off control as an example for description.

[0116] The control circuit can adjust the zero current detection reference value according to the current direction during zero current switching. To describe this example, the current direction from one side of the inductor to the other side (from the third node (refer to Figure 2 N3 in the flow to the sixth node (see Figure 2 The current direction of N6 in is defined as forward.

[0117] Fig.11 is a schematic diagram of main waveforms when the third switch is cut off when the current flows in the forward direction in one embodiment, and Fig.12 FIG. 4 is a schematic diagram of main waveforms when the third switch is turned off when the current flows in the negative direction in one embodiment.

[0118] See also Fig.11 and Fig.12 , the control circuit may cut off the third switch Q3 at the third time point T3. Although not shown, the control circuit may 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, cutting off) of the third switch Q3. In addition, the third switch Q3 may be actually cut off at the third time point T3.

[0119] See also Fig.11 At a time point T4 after the zero current switching, the drain voltage V SW Can be expressed as lower than the source voltage V N4 The voltage V N4 -V d , this waveform can appear when the current is formed in the forward direction. Among them, V d is the drain voltage V SW and source voltage V N4 The voltage difference between them may be the same as the forward voltage drop voltage of the diode of the third switch Q3.

[0120] See also Fig.12At a time point T4 after the zero current switching, the drain voltage V SW Can represent a voltage higher than the source voltage V N4 The voltage V N4 +V d , this waveform can appear when the current is negative. Among them, V d is the drain voltage V SW and source voltage V N4 The voltage difference between them may be the same as the voltage of the parasitic capacitance formed in the third switch Q3.

[0121] The control circuit can determine the current direction by comparing the drain voltage value and the source voltage value, and increase or decrease the zero current detection reference value according to the current direction. When the zero current detection reference value is high, when the current flows in the positive direction, switching control is likely to occur; when the zero current detection reference value is low, when the current flows in the negative direction, switching control is likely to occur. Therefore, when the direction of the current determined by the drain voltage value and the source voltage value is positive, the control circuit can reduce the zero current detection reference value, and when it is negative, the zero current detection reference value can be increased. Alternatively, the control circuit can increase or decrease the zero current detection reference value according to the trend of the drain voltage value and the source voltage value decreasing.

[0122] Fig.13 is a schematic diagram of main waveforms when the fourth switch is cut off when the current flows in the forward direction in one embodiment, and Fig.14 FIG. 4 is a schematic diagram of main waveforms when the third switch is turned off when the current flows in the negative direction in one embodiment.

[0123] See also Fig.13 and Fig.14 , the control circuit may cut off the fourth switch Q4 at the fifth time point T5. Although not shown in the figure, the control circuit may compare the current value of the fourth switch Q4 with the zero current detection reference value at a time point earlier than the fifth time point T5 to control the zero current switching (here, cutting off) of the fourth switch Q4. In addition, the fourth switch Q4 may be actually cut off at the fifth time point T5.

[0124] See also Fig.13 At a time point T6 after the zero current switching, the drain voltage V N4 Can be expressed as lower than the source voltage V N5 The voltage V N5 -V d , this waveform can appear when the current is formed in the forward direction. Among them, V d is the drain voltage V N4 and source voltage V N5 The voltage difference between them may be the same as the forward voltage drop voltage of the diode of the fourth switch Q4.

[0125] See also Fig.14 At a time point T6 after the zero current switching, the drain voltage V N4 Can represent a voltage higher than the source voltage V N5 The voltage V N5 +V d , this waveform can appear when the current is negative. Among them, V d is the drain voltage V N4 and source voltage V N5 The voltage difference between them may be the same as the voltage of the parasitic capacitance of the fourth switch Q4.

[0126] The control circuit can determine the current direction by comparing the drain voltage value and the source voltage value, and increase or decrease the zero current detection reference value according to the current direction. When the zero current detection reference value is high, when the current flows in the positive direction, switching control is likely to occur; when the zero current detection reference value is low, when the current flows in the negative direction, switching control is likely to occur. Therefore, when the direction of the current determined by the drain voltage value and the source voltage value is positive, the control circuit can reduce the zero current detection reference value, and when it is negative, the zero current detection reference value can be increased. Alternatively, the control circuit can increase or decrease the zero current detection reference value according to the trend of the drain voltage value and the source voltage value decreasing.

[0127] The adjustment of the zero current detection reference value may be performed periodically or irregularly. For example, the control circuit may adjust the zero current detection reference value once in each switching cycle or every N (N is a natural number greater than or equal to 2) switching cycles.

[0128] As described above, according to the present embodiment, the efficiency of the switching regulator can be improved by optimal zero current switching. In addition, according to the present embodiment, the process of adjusting the zero current detection reference value through mass production testing is eliminated, thereby shortening the manufacturing time of the switching regulator. In addition, according to the present embodiment, even if the input voltage, output voltage and inductance change in the switching regulator, the zero current detection reference value can be adaptively set.

[0129] In the content, the terms "including", "consisting of" or "having" recorded, unless there is an expected record to the contrary, indicate that the corresponding constituent elements may be included, and other components are not excluded but may also be included. Unless otherwise specified, the meaning of all terms including technical or scientific terms is the same as that generally understood by technicians in the technical field to which the utility model belongs. Generally used terms such as terms defined in dictionaries have the same meaning as in the context of the relevant technology, and do not have ideal or excessive meanings in this application unless clearly defined.

[0130] The embodiments are intended to illustrate the present invention but are not intended to limit the present invention. It should be understood by those skilled in the art that the present invention may be modified, deformed or replaced by equivalents without departing from the spirit and scope of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A switching regulator, comprising: A switch network, comprising a first switch block, a second switch block, a third switch block and a fourth switch block connected in series, a flying capacitor connected to a first node connected to the first switch block and the second switch block and a second node connected to the third switch block and the fourth switch block, and an inductor connected to a third node connected to the second switch block and the third switch block; and A control circuit 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 the zero current switching of the one switch block, and compares the voltage value of one end of the one switch block confirmed at a time point after the zero current switching with the voltage value of the other end to adjust the zero current detection reference value. 2 . The switching regulator according to claim 1 , wherein there is a fixed time delay between a time point at which the current value of a switching block is compared with the zero current detection reference value and a time point at which the switching block is controlled to switch zero current.

3. The switching regulator according to claim 1, wherein the control circuit, when the first switch block and the third switch block are turned on, only cuts off the third switch block according to zero current switching control, and compares the drain voltage value and the source voltage value of the third switch block after the third switch block is cut off to adjust the zero current detection reference value.

4. The switching regulator according to claim 3, wherein the control circuit determines that the third switch block is cut off when the current flows from the third switch block to the direction of the inductor when the drain voltage value of the third switch block after the third switch block is cut off is lower than the source voltage value; and determines that the third switch block is cut off when the current flows from the inductor to the direction of the third switch block when the drain voltage value of the third switch block is higher than the source voltage value. 5 . The switching regulator according to claim 4 , wherein the control circuit increases or decreases the zero current detection reference value according to a direction of current.

6. The switching regulator according to claim 1, wherein the control current, when the second switch block and the fourth switch block are turned on, only cuts off the fourth switch block according to zero current switching control, and compares the drain voltage value and the source voltage value of the fourth switch block after the fourth switch block is cut off to adjust the zero current detection reference value.

7. The switching regulator according to claim 1, wherein the control circuit can control the switch network through the following states: 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; the first state and the second state are controlled to alternate so that the switch network operates as a buck converter or a boost converter; the third state and the four states are controlled to alternate so that the switch network operates as a resonant converter. 8 . The switching regulator according to claim 7 , wherein the control circuit ends the third state or the fourth state by zero current switching. 9 . The switching regulator according to claim 1 , wherein a transistor, a diode and a parasitic capacitor are formed in parallel on the one switching block.

10. A switching regulator comprising: A switch provided in a path through which the inductor current flows; and The control circuit compares the current value of the switch with a zero current detection reference value to control the zero current switching of the switch, and compares the voltage value of one end and the voltage value of the other end of the switch confirmed at a time point after the zero current switching to adjust the zero current detection reference value. 11 . The switching regulator according to claim 10 , wherein there is a fixed time delay between the time point at which the current value of a switch is compared with the zero current detection reference value and the time point at which the switch is controlled to switch zero current. 12 . The switching regulator according to claim 10 , wherein the control circuit adjusts the zero current detection reference value according to a decreasing trend of a difference between a voltage value at the one end and a voltage value at the other end of the switch.

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

14. The switching regulator according to claim 13, wherein when the direction of current flowing from the switch to the inductor is defined as a forward direction, the control circuit determines that the switch is cut off when the current flows in a forward direction when the drain voltage value confirmed by the control circuit at a time point after zero current switching is lower than the source voltage value; and determines that the switch is cut off when the current flows in a negative direction when the drain voltage value is higher than the source voltage value. 15 . The switching regulator according to claim 14 , wherein the control circuit increases or decreases the zero current detection reference value according to a direction of current.

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