Driving circuit and switching power supply

Abstract

The utility model discloses a drive circuit and a switching power supply, and the drive circuit comprises a signal processing circuit which amplifies a first drive signal inputted by a first input end of the signal processing circuit into a second drive signal when a first enable end receives a first enable signal, and outputs the second drive signal through a first output end of the signal processing circuit; when the second enable end receives a second enable signal, the first PWM signal input by the second input end of the second enable end is amplified into a second PWM signal, and the second PWM signal is output by the second output end of the second enable end; the input end of the isolated power supply generating circuit is connected with the second output end of the signal processing circuit, and the isolated power supply generating circuit is used for isolating and converting the second PWM signal into a first isolated power supply and outputting the first isolated power supply through the output end; the input end of the driving signal isolation circuit is connected with the first output end of the signal processing circuit, the power supply end of the driving signal isolation circuit is connected with the output end of the isolation power supply generation circuit, and the driving signal isolation circuit is used for isolating the second driving signal into a third driving signal and outputting the third driving signal through the output end. According to the utility model, hardware quantity can be saved.

Description

Technical Field

[0001] The utility model relates to the field of switch converters, in particular to a drive circuit and a switch power supply. Background Art

[0002] With the rapid development of digital power supplies, there are more and more types of power topologies. Power tubes in some topologies need to be isolated and driven. Not only the drive signal needs to be isolated, but also the power supply signal for internal active devices (such as optocouplers) needs to be isolated. In addition, the proximity principle needs to be considered when designing isolated power supplies and isolated signals.

[0003] However, some topologies require multiple sets of isolated power supplies and isolated signals for a single machine. For example, in a three-phase six-switch PFC circuit, the three upper bridge arm switches floating to the ground each require a set of isolated power supplies and isolated signals, and the three lower bridge arm switches located at the low end can share a set of isolated power supplies and isolated signals, requiring a total of four sets of isolated power supplies and isolated signals. For such application scenarios, in order to generate isolated power signals, the traditional solution for generating isolated power supplies is as follows:

[0004] (1) Generate isolated power supply signals through PWM controllers (such as UCC3842) and transformers. The PWM controller requires independent power supply and peripheral circuit frequency setting, and the upper frequency limit is low. This not only makes the circuit structure complex, but also makes the isolation transformer larger. In this case, multiple sets of PWM controllers and transformers are required just to generate isolated power supply, which not only increases the cost but also brings challenges to the layout.

[0005] (2) Generate multiple isolated power signals through a multi-output DC / DC flyback power supply. This requires an independent flyback power supply system, which is not only large in size and high in cost, but also may cause crosstalk between the isolated windings, resulting in abnormal driving. Utility Model Content

[0006] In view of this, the technical problem to be solved by the present invention is to provide a driving circuit and a switching power supply, which can at least solve one of the technical problems existing in the above-mentioned prior art to a certain extent.

[0007] As a first aspect of the present invention, the technical solution of the embodiment of the driving circuit provided is as follows:

[0008] A driving circuit, comprising:

[0009] A signal processing circuit, comprising a first input terminal, a second input terminal, a first enable terminal, a second enable terminal, a first output terminal, and a second output terminal, wherein: when the first enable terminal receives a first enable signal, the signal processing circuit amplifies a first drive signal inputted from the first input terminal into a second drive signal, and then outputs the second drive signal from the first output terminal; when the second enable terminal receives a second enable signal, the signal processing circuit amplifies a first PWM signal inputted from the second input terminal into a second PWM signal, and then outputs the second PWM signal from the second output terminal;

[0010] An isolated power supply generating circuit, comprising an input end and an output end, wherein the input end is connected to the second output end of the signal processing circuit, and the isolated power supply generating circuit is used to isolate and convert the second PWM signal into a first isolated power supply, and then output it from the output end;

[0011] The drive signal isolation circuit comprises an input end, an output end and a power supply end, wherein the input end is connected to the first output end of the signal processing circuit, and the power supply end is connected to the output end of the isolated power supply generating circuit. The drive signal isolation circuit is used to isolate and process the second drive signal into a third drive signal, which is then outputted from the output end.

[0012] Preferably, the signal processing circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a voltage driving chip U1; one end of the resistor R1 is the first input end of the signal processing circuit, one end of the resistor R3 is the second input end of the signal processing circuit, one end of the resistor R2 and one end of the resistor R4 are both connected to the primary signal ground of the voltage driving chip U1, the other end of the resistor R1 and the other end of the resistor R2 are both connected to the first primary low-voltage signal input end of the voltage driving chip U1, the other end of the resistor R3 and the other end of the resistor R4 are both connected to the second primary low-voltage signal input end of the voltage driving chip U1, the first enable pin of the voltage driving chip U1 is the first enable pin of the signal processing circuit, the second enable pin of the voltage driving chip U1 is the second enable pin of the signal processing circuit, the first secondary high-voltage signal output end of the voltage driving chip U1 is the first output end of the signal processing circuit, and the second secondary high-voltage signal output end of the voltage driving chip U1 is the second output end of the signal processing circuit.

[0013] Preferably, the voltage driving chip U1 is SGM48524, UCC27524 or UCC27525.

[0014] Preferably, the isolated power supply generating circuit adopts an asymmetric flyback circuit.

[0015] Preferably, the asymmetric flyback circuit includes a capacitor C1, a transformer T1, a capacitor C2, a capacitor C3, a diode D1 and a diode D2; one end of the capacitor C1 is the input end of the isolated power supply generating circuit, the other end of the capacitor C1 is connected to the same-name end of the primary winding of the transformer T1, the opposite-name end of the primary winding of the transformer T1 is used to connect to the primary signal ground, the same-name end of the secondary winding of the transformer T1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is simultaneously connected to the cathode of the diode D1 and the anode of the diode D2, the cathode of the diode D2 and one end of the capacitor C3 are connected together as the output end of the isolated power supply generating circuit, the opposite-name end of the secondary winding of the transformer T1, the anode of the diode D1 and the other end of the capacitor C3 are connected together for connecting to the secondary signal ground.

[0016] Preferably, the drive signal isolation circuit includes a resistor R5 and an optocoupler U2, one end of the resistor R5 is the input end of the drive signal isolation circuit, the other end of the resistor R5 is connected to the primary anode pin of the optocoupler U2, the power supply pin of the optocoupler U2 is the power supply end of the drive signal isolation circuit, and the secondary output pin of the optocoupler U2 is the output end of the drive signal isolation circuit.

[0017] Preferably, the signal processing circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a voltage driving chip U1; one end of the resistor R1 is a first input end of the signal processing circuit, one end of the resistor R3 is a second input end of the signal processing circuit, one end of the resistor R2 and one end of the resistor R4 are both connected to the primary signal ground of the voltage driving chip U1, the other end of the resistor R1 and the other end of the resistor R2 are both connected to the first primary low-voltage signal input end of the voltage driving chip U1, the other end of the resistor R3 and the other end of the resistor R4 are both connected to the second primary low-voltage signal input end of the voltage driving chip U1, the first enable pin of the voltage driving chip U1 is the first enable pin of the signal processing circuit, the second enable pin of the voltage driving chip U1 is the second enable pin of the signal processing circuit, the first secondary high-voltage signal output end of the voltage driving chip U1 is the first output end of the signal processing circuit, and the second secondary high-voltage signal output end of the voltage driving chip U1 is the second output end of the signal processing circuit;

[0018] The isolated power supply generating circuit comprises a capacitor C1, a transformer T1, a capacitor C2, a capacitor C3, a diode D1 and a diode D2; one end of the capacitor C1 is the input end of the isolated power supply generating circuit, the other end of the capacitor C1 is connected to the same-name end of the primary winding of the transformer T1, the opposite-name end of the primary winding of the transformer T1 is used to connect to the primary signal ground, the same-name end of the secondary winding of the transformer T1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is simultaneously connected to the cathode of the diode D1 and the anode of the diode D2, the cathode of the diode D2 and one end of the capacitor C3 are connected together as the output end of the isolated power supply generating circuit, the opposite-name end of the secondary winding of the transformer T1, the anode of the diode D1 and the other end of the capacitor C3 are connected together to connect to the secondary signal ground;

[0019] The drive signal isolation circuit includes a resistor R5 and an optocoupler U2, one end of the resistor R5 is the input end of the drive signal isolation circuit, the other end of the resistor R5 is connected to the primary anode pin of the optocoupler U2, the power supply pin of the optocoupler U2 is the power supply end of the drive signal isolation circuit, and the secondary output pin of the optocoupler U2 is the output end of the drive signal isolation circuit.

[0020] As a second aspect of the present invention, the technical solution of the embodiment of the switching power supply provided is as follows:

[0021] A switching power supply, comprising a power tube, characterized in that: the switching power supply also comprises a driving circuit as described in any one of the first aspects above, and the third driving signal output by the driving circuit is used to control the conduction and shutdown of the power tube.

[0022] Preferably, the power tube is a MOS tube or an IGBT.

[0023] Preferably, the switching power supply comprises a three-phase six-switch PFC circuit.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The signal processing circuit generates a second drive signal and a second PWM signal at the same time, the isolated power supply generating circuit isolates and converts the second PWM signal into a first isolated power supply to power the drive signal isolation circuit, and the drive signal isolation circuit isolates and processes the second drive signal into a third drive signal, that is, the isolated power supply is generated by multiplexing the signal processing circuit, which can save the number of hardware and reduce costs, and it is easy to meet the principle of nearby design of isolated power supply and isolated signal, thereby reducing the local difficulty of PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a specific schematic diagram of the driving circuit of the utility model. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0028] It should be noted that the terms "including" and "having" and any variations thereof described in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, the inclusion of a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings clearly listed, but may include components, unit circuits or control timings that are not clearly listed or inherent to these circuits.

[0029] In addition, the embodiments and features of the embodiments in this application may be combined with each other if there is no conflict.

[0030] It should be understood that, in the specification and the claims, when an element is described as being “connected” to another element, the element may be “directly connected” to the other element, or be “connected” to the other element through a third element; when a step is described as being continued to another step, the step may be directly continued to the other step, or be continued to the other step through a third step.

[0031] First embodiment

[0032] This embodiment provides a driving circuit, which includes:

[0033] A signal processing circuit, comprising a first input terminal, a second input terminal, a first enable terminal, a second enable terminal, a first output terminal, and a second output terminal, wherein: when the first enable terminal receives a first enable signal, the signal processing circuit amplifies a first drive signal Drv_A inputted from the first input terminal into a second drive signal Drv_AO, and then outputs the signal from the first output terminal; when the second enable terminal receives a second enable signal, the signal processing circuit amplifies a first PWM signal PWM_V inputted from the second input terminal into a second PWM signal PWM_VO, and then outputs the signal from the second output terminal;

[0034] An isolated power supply generating circuit, comprising an input end and an output end, wherein the input end is connected to the second output end of the signal processing circuit, and the isolated power supply generating circuit is used to isolate and convert the second PWM signal PWM_VO into a first isolated power supply VSS, which is then outputted from the output end;

[0035] The drive signal isolation circuit includes an input end, an output end and a power supply end, wherein the input end is connected to the first output end of the signal processing circuit, and the power supply end is connected to the output end of the isolation power supply generating circuit. The drive signal isolation circuit is used to isolate and process the second drive signal Drv_AO into a third drive signal Drv_AOO, and then output it from its output end.

[0036] The signal processing circuit of this embodiment simultaneously generates a second drive signal Drv_AO and a second PWM signal PWM_VO. The isolated power supply generating circuit isolates and converts the second PWM signal PWM_VO into a first isolated power supply to power the drive signal isolation circuit. The drive signal isolation circuit isolates and processes the second drive signal Drv_AO into a third drive signal Drv_AOO. That is, the isolated power supply is generated by multiplexing the signal processing circuit, which can save the number of hardware and reduce costs, and easily meet the principle of nearby design of isolated power supplies and isolated signals, thereby reducing the local difficulty of the PCB.

[0037] Figure 1 For a specific schematic diagram of the drive circuit of the utility model, please refer to Figure 1 , wherein: the signal processing circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a voltage driving chip U1; one end of the resistor R1 is the first input end of the signal processing circuit, one end of the resistor R3 is the second input end of the signal processing circuit, one end of the resistor R2 and one end of the resistor R4 are both connected to the primary signal ground PGND of the voltage driving chip U1, the other end of the resistor R1 and the other end of the resistor R2 are both connected to the first primary low-voltage signal input end INA of the voltage driving chip U1, the other end of the resistor R3 and the other end of the resistor R4 are both connected to the second primary low-voltage signal input end INB of the voltage driving chip U1, the first enable pin ENA of the voltage driving chip U1 is the first enable pin of the signal processing circuit, the second enable pin ENB of the voltage driving chip U1 is the second enable pin of the signal processing circuit, the first secondary high-voltage signal output end OUTA of the voltage driving chip U1 is the first output end of the signal processing circuit, and the second secondary high-voltage signal output end OUTB of the voltage driving chip U1 is the second output end of the signal processing circuit.

[0038] The resistors R1, R2, R3 and R4 are used to keep the DC bias basically unchanged.

[0039] The function of the voltage driver chip U1 is to convert the low voltage signal into a high voltage signal. For example, you can choose SGM48524 from Shengbang Microelectronics, UCC27524 from Texas Instruments, or UCC27525 from Texas Instruments. The pins of these chips are compatible and are defined as follows:

[0040] Pin 1: Enable signal input pin ENA of channel 1;

[0041] Pin 2: Primary low voltage signal input pin INA of channel 1;

[0042] Pin 7: secondary side high voltage signal output pin OUTA of channel 1;

[0043] Pin 3: Chip ground pin GND;

[0044] Pin 6: Chip power supply pin VCC;

[0045] Pin 8: Enable signal input pin ENB of channel 2;

[0046] Pin 4: Primary low voltage signal input pin INB of channel 2;

[0047] Pin 5: Secondary side high voltage signal output pin OUTB of channel 2.

[0048] Please continue to see Figure 1 , wherein: the isolated power supply generating circuit adopts an asymmetric flyback circuit, because the primary circuit of the asymmetric flyback circuit only needs one DC blocking capacitor, the circuit structure is simple, the cost is low, and the required isolation transformer is small in size. At the same time, the circuit layout can be close to the isolation device used to isolate the driving signal.

[0049] Specifically, the asymmetric flyback circuit includes a capacitor C1, a transformer T1, a capacitor C2, a capacitor C3, a diode D1 and a diode D2; one end of the capacitor C1 is the input end of the isolated power supply generating circuit, the other end of the capacitor C1 is connected to the same-name end of the primary winding of the transformer T1, the opposite-name end of the primary winding of the transformer T1 is used to connect to the primary signal ground PGND, the same-name end of the secondary winding of the transformer T1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is simultaneously connected to the cathode of the diode D1 and the anode of the diode D2, the cathode of the diode D2 and one end of the capacitor C3 are connected together as the output end of the isolated power supply generating circuit, the opposite-name end of the secondary winding of the transformer T1, the anode of the diode D1 and the other end of the capacitor C3 are connected together for connecting to the secondary signal ground SGND.

[0050] Please continue to see Figure 1 , wherein: the drive signal isolation circuit includes a resistor R5 and an optocoupler U2, one end of the resistor R5 is the input end of the drive signal isolation circuit, the other end of the resistor R5 is connected to the primary anode pin of the optocoupler U2, the power supply pin of the optocoupler U2 is the power supply end of the drive signal isolation circuit, and the secondary output pin of the optocoupler U2 is the output end of the drive signal isolation circuit.

[0051] Figure 1 The working principle of the circuit is analyzed as follows:

[0052] After the PWM signal PWM_V passes through the voltage driver chip U1, a PWM signal PWM_VO with an amplitude voltage of VCC is generated. After the PWM_VO signal passes through the isolation power supply circuit composed of capacitor C1, transformer T1, capacitor C2, diode D1, diode D2 and capacitor C3, an isolation power supply VSS is generated. The voltage of the isolation power supply VSS = VCC*N1 / N2 (N1 / N2 is the turns ratio of transformer T1). The isolation power supply VSS supplies power to the optocoupler U2.

[0053] After the driving signal Drv_A passes through the voltage driving chip U1, the driving signal Drv_AO with an amplitude voltage of VCC is generated. After the driving signal Drv_AO passes through the current limiting resistor R5, it directly provides a power supply circuit to the primary side of the optocoupler U2: when the driving signal Drv_AO is at a high level, the primary side of the optocoupler U2 is turned on, and the optocoupler pin 5 outputs a high-level driving signal Drv_AOO with an amplitude of VSS, and the driven power tube is turned on; when the driving signal Drv_AO is at a low level, the primary side of the optocoupler U2 is turned off, and the optocoupler pin 5 outputs a low-level driving signal Drv_AOO, and the driven power tube is turned off.

[0054] Second embodiment

[0055] This embodiment provides a switching power supply, which includes a power tube, wherein: the switching power supply also includes any one of the drive circuits in the first embodiment, and the third drive signal output by the drive circuit is used to control the conduction and shutdown of the power tube.

[0056] Since the switching power supply of this embodiment includes any one of the driving circuits in the first embodiment to control the on and off of the power tube, it can save the number of hardware and reduce costs, and it is easy to meet the principle of designing the isolated power supply and the isolated signal nearby, reducing the local difficulty of the PCB.

[0057] Preferably, the power tube is a MOS tube or an IGBT.

[0058] Preferably, the switching power supply comprises a three-phase six-switch PFC circuit.

[0059] The above are only implementation modes of the present invention. It should be pointed out that the above implementation modes should not be regarded as limitations of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A driving circuit, characterized in that: include: A signal processing circuit, comprising a first input terminal, a second input terminal, a first enable terminal, a second enable terminal, a first output terminal, and a second output terminal, wherein: when the first enable terminal receives a first enable signal, the signal processing circuit amplifies a first drive signal inputted from the first input terminal into a second drive signal, and then outputs the second drive signal from the first output terminal; when the second enable terminal receives a second enable signal, the signal processing circuit amplifies a first PWM signal inputted from the second input terminal into a second PWM signal, and then outputs the second PWM signal from the second output terminal; An isolated power supply generating circuit, comprising an input end and an output end, wherein the input end is connected to the second output end of the signal processing circuit, and the isolated power supply generating circuit is used to isolate and convert the second PWM signal into a first isolated power supply, and then output it from the output end; The drive signal isolation circuit comprises an input end, an output end and a power supply end, wherein the input end is connected to the first output end of the signal processing circuit, and the power supply end is connected to the output end of the isolated power supply generating circuit. The drive signal isolation circuit is used to isolate and process the second drive signal into a third drive signal, which is then outputted from the output end.

2. The driving circuit according to claim 1, characterized in that: The signal processing circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a voltage driving chip U1; one end of the resistor R1 is the first input end of the signal processing circuit, one end of the resistor R3 is the second input end of the signal processing circuit, one end of the resistor R2 and one end of the resistor R4 are both connected to the primary signal ground of the voltage driving chip U1, the other end of the resistor R1 and the other end of the resistor R2 are both connected to the first primary low-voltage signal input end of the voltage driving chip U1, the other end of the resistor R3 and the other end of the resistor R4 are both connected to the second primary low-voltage signal input end of the voltage driving chip U1, the first enable pin of the voltage driving chip U1 is the first enable pin of the signal processing circuit, the second enable pin of the voltage driving chip U1 is the second enable pin of the signal processing circuit, the first secondary high-voltage signal output end of the voltage driving chip U1 is the first output end of the signal processing circuit, and the second secondary high-voltage signal output end of the voltage driving chip U1 is the second output end of the signal processing circuit.

3. The driving circuit according to claim 2, characterized in that: The voltage driving chip U1 is SGM48524, UCC27524 or UCC27525.

4. The driving circuit according to claim 1, characterized in that: The isolated power supply generating circuit adopts an asymmetric flyback circuit.

5. The driving circuit according to claim 4, characterized in that: The asymmetric flyback circuit includes a capacitor C1, a transformer T1, a capacitor C2, a capacitor C3, a diode D1 and a diode D2; one end of the capacitor C1 is the input end of the isolated power supply generating circuit, the other end of the capacitor C1 is connected to the same-name end of the primary winding of the transformer T1, the opposite-name end of the primary winding of the transformer T1 is used to connect to the primary signal ground, the same-name end of the secondary winding of the transformer T1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is simultaneously connected to the cathode of the diode D1 and the anode of the diode D2, the cathode of the diode D2 and one end of the capacitor C3 are connected together as the output end of the isolated power supply generating circuit, the opposite-name end of the secondary winding of the transformer T1, the anode of the diode D1 and the other end of the capacitor C3 are connected together for connecting to the secondary signal ground.

6. The driving circuit according to claim 1, characterized in that: The drive signal isolation circuit includes a resistor R5 and an optocoupler U2, one end of the resistor R5 is the input end of the drive signal isolation circuit, the other end of the resistor R5 is connected to the primary anode pin of the optocoupler U2, the power supply pin of the optocoupler U2 is the power supply end of the drive signal isolation circuit, and the secondary output pin of the optocoupler U2 is the output end of the drive signal isolation circuit.

7. The driving circuit according to claim 1, characterized in that: The signal processing circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a voltage driving chip U1; one end of the resistor R1 is the first input end of the signal processing circuit, one end of the resistor R3 is the second input end of the signal processing circuit, one end of the resistor R2 and one end of the resistor R4 are both connected to the primary signal ground of the voltage driving chip U1, the other end of the resistor R1 and the other end of the resistor R2 are both connected to the first primary low-voltage signal input end of the voltage driving chip U1, the other end of the resistor R3 and the other end of the resistor R4 are both connected to the second primary low-voltage signal input end of the voltage driving chip U1, the first enable pin of the voltage driving chip U1 is the first enable pin of the signal processing circuit, the second enable pin of the voltage driving chip U1 is the second enable pin of the signal processing circuit, the first secondary high-voltage signal output end of the voltage driving chip U1 is the first output end of the signal processing circuit, and the second secondary high-voltage signal output end of the voltage driving chip U1 is the second output end of the signal processing circuit; The isolated power supply generating circuit comprises a capacitor C1, a transformer T1, a capacitor C2, a capacitor C3, a diode D1 and a diode D2; one end of the capacitor C1 is the input end of the isolated power supply generating circuit, the other end of the capacitor C1 is connected to the same-name end of the primary winding of the transformer T1, the opposite-name end of the primary winding of the transformer T1 is used to connect to the primary signal ground, the same-name end of the secondary winding of the transformer T1 is connected to one end of the capacitor C2, the other end of the capacitor C2 is simultaneously connected to the cathode of the diode D1 and the anode of the diode D2, the cathode of the diode D2 and one end of the capacitor C3 are connected together as the output end of the isolated power supply generating circuit, the opposite-name end of the secondary winding of the transformer T1, the anode of the diode D1 and the other end of the capacitor C3 are connected together to connect to the secondary signal ground; The drive signal isolation circuit includes a resistor R5 and an optocoupler U2, one end of the resistor R5 is the input end of the drive signal isolation circuit, the other end of the resistor R5 is connected to the primary anode pin of the optocoupler U2, the power supply pin of the optocoupler U2 is the power supply end of the drive signal isolation circuit, and the secondary output pin of the optocoupler U2 is the output end of the drive signal isolation circuit.

8. A switching power supply, comprising a power tube, characterized in that: The switching power supply further comprises the driving circuit as claimed in any one of claims 1 to 7, and the third driving signal output by the driving circuit is used to control the on and off of the power tube.

9. The switching power supply according to claim 8, characterized in that: The power tube is a MOS tube or an IGBT.

10. The switching power supply according to claim 8, characterized in that: The switching power supply includes a three-phase six-switch PFC circuit.

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