Power supply circuit and switching power supply

Abstract

The utility model discloses a power supply circuit, which comprises a power conversion circuit, a communication interface circuit, a first chip, a second chip and a switching circuit, the power conversion circuit is used for connecting a power input end and performing power conversion on the electric signal output by the power input end; the communication interface circuit is connected with the power conversion circuit and used for being connected with load equipment and obtaining electric quantity information of the load equipment; the first chip is connected with the communication interface circuit and is used for outputting a first control signal according to the electric quantity information; the second chip is connected with the first chip and the power conversion circuit and is used for receiving the first control signal and outputting a second control signal; and the switching circuit is arranged between the power supply input end and the power conversion circuit, is connected with the second chip and is used for being switched on or switched off according to the second control signal. According to the technical scheme, the loss of the power supply circuit can be reduced, meanwhile, faults caused by device aging and unstable power grid voltage are reduced, and the safety in the charging process is ensured.

Description

Technical Field

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

[0002] Currently, consumers do not unplug the charger after charging their mobile phones. Leaving the charger plugged in for a long time will accelerate the aging of the internal components of the charger. Coupled with the voltage fluctuation of the power grid itself, it is very easy to cause charger failure or even fire. To address the above problems, there are the following existing technical solutions: adding NTC (Negative Temperature Coefficient, negative temperature coefficient, abbreviated as NTC) resistors to the charger to monitor the internal temperature of the charger in real time. If the internal temperature of the charger is higher than the set value, the charger stops working.

[0003] However, the most common reason for charger failure on the market is the bulging and leakage of the input high-voltage electrolytic capacitor, which can easily cause the charger to have a semi-short circuit, which can lead to a fire. Therefore, even if the NTC resistor detects that the internal temperature is higher than the set value, the input high-voltage electrolytic capacitor is still connected to the circuit, and after the input high-voltage electrolytic capacitor leaks, the charger will still have a semi-short circuit fire problem. Therefore, how to improve the safety of the charging process has become a technical problem that needs to be solved urgently. Utility Model Content

[0004] The embodiments of the utility model provide a power supply circuit and a switching power supply to solve the problem of poor safety of a mobile phone during charging.

[0005] A power supply circuit comprises a power conversion circuit, a communication interface circuit, a first chip, a second chip and a switch circuit;

[0006] The power conversion circuit is used to connect to the power input terminal and perform power conversion on the electrical signal output by the power input terminal;

[0007] The communication interface circuit is connected to the power conversion circuit and is used to connect to a load device to obtain power information of the load device;

[0008] The first chip is connected to the communication interface circuit and is used to output a first control signal according to the power information;

[0009] The second chip is connected to the first chip and the power conversion circuit, and is used to receive the first control signal and output a second control signal;

[0010] The switch circuit is arranged between the power input terminal and the power conversion circuit and connected to the second chip, and is used for being turned on or off according to the second control signal.

[0011] Furthermore, the switch circuit includes a first switch tube;

[0012] The first end of the first switch tube is connected to the power input end, the second end of the first switch tube is connected to the power conversion circuit, and the third end of the first switch tube is connected to the second chip.

[0013] Furthermore, the power supply circuit also includes a first capacitor, a first end of the first capacitor is connected to a connection node between the power conversion circuit and a second end of the first switch tube, and a second end of the first capacitor is grounded.

[0014] Furthermore, the power supply circuit also includes a photocoupler;

[0015] The photoelectric coupler is connected to the first chip and the second chip, and is used for transmitting the first control signal.

[0016] Further, the photoelectric coupler includes a light emitting diode and a phototransistor;

[0017] The light emitting diode is connected to the first chip, and the phototransistor is connected to the second chip.

[0018] Further, the power conversion circuit includes a primary winding, a main secondary winding and an auxiliary secondary winding;

[0019] The first end of the primary winding is used to connect to the power input terminal, and the second end of the primary winding is grounded;

[0020] The first end of the primary and secondary windings is connected to the communication interface circuit, and the second end of the primary and secondary windings is grounded;

[0021] A first end of the auxiliary secondary winding is connected to the second chip, and a second end of the auxiliary secondary winding is grounded.

[0022] Furthermore, the communication interface circuit includes a USB-C interface, a power supply end of the USB-C is connected to the power conversion circuit, and a communication end of the USB-C is connected to the first chip.

[0023] Furthermore, the power supply circuit also includes a second switch tube;

[0024] The first end of the second switch tube is connected to the second end of the primary winding, and the second end of the second switch tube is grounded through a first resistor; the third end of the second switch tube is connected to the first control end of the second chip;

[0025] The first detection end of the second chip is connected to a connection node between the second end of the second switch tube and the first resistor, and is used to detect an overcurrent protection signal.

[0026] Furthermore, the power supply circuit also includes a third switch tube, a first end of the third switch tube is connected to the power conversion circuit, a second end of the third switch tube is connected to the communication interface circuit, and a third end of the third switch tube is connected to the first chip.

[0027] A switching power supply comprises the above power supply circuit.

[0028] The above-mentioned power supply circuit and switching power supply, the power supply circuit includes a power conversion circuit, a communication interface circuit, a first chip, a second chip and a switching circuit; the power conversion circuit is used to connect to the power input end and perform power conversion on the electrical signal output from the power input end; the communication interface circuit is connected to the power conversion circuit and is used to connect to the load device and obtain the power information of the load device; the first chip is connected to the communication interface circuit and is used to output a first control signal according to the power information; the second chip is connected to the first chip and the power conversion circuit and is used to receive the first control signal and output the second control signal; the switching circuit is arranged between the power input end and the power conversion circuit and is connected to the second chip and is used to be turned on or off according to the second control signal, so that the switching circuit can disconnect the power circuit and the load device after the load device completes charging, thereby reducing the loss of the power circuit, and at the same time reducing the occurrence of faults caused by device aging and unstable grid voltage, thereby ensuring the safety of the charging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a circuit diagram of a power supply circuit in one embodiment of the utility model.

[0031] In the figure: 1. power conversion circuit; 2. communication interface circuit; 3. first chip; 4. second chip; 5. switch circuit. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] It should be understood that the utility model can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and fully convey the scope of the utility model to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0034] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. On the contrary, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0035] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0036] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present invention. When used herein, the singular forms "a", "an" and " / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0037] In order to thoroughly understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0038] This embodiment provides a power supply circuit, such as Figure 1 As shown, it includes a power conversion circuit 1, a communication interface circuit 2, a first chip 3 (U2), a second chip 4 (U1) and a switch circuit 5; the power conversion circuit 1 is used to connect to a power input terminal (not shown in the figure) and perform power conversion on an electrical signal output from the power input terminal; the communication interface circuit 2 is connected to the power conversion circuit 1 and is used to connect to a load device and obtain power information of the load device; the first chip 3 is connected to the communication interface circuit 2 and is used to output a first control signal according to the power information; the second chip 4 is connected to the first chip 3 and the power conversion circuit 1 and is used to receive the first control signal and output a second control signal; the switch circuit 5 is arranged between the power input terminal and the power conversion circuit 1 and is connected to the second chip 4 and is used to turn on or off according to the second control signal.

[0039] As an example, the electrical signal output from the power input terminal includes a voltage signal and a current signal. The power conversion circuit 1 converts the voltage signal and the current signal to achieve power conversion of the power circuit to meet the charging requirements of different load devices. It can be understood that the load device includes a mobile phone, a computer or other electronic device. In this example, the power conversion circuit 1 is used to connect to the power input terminal and perform power conversion on the electrical signal output from the power input terminal to meet the power requirements of the load device.

[0040] As an example, the communication interface circuit 2 is connected to the power conversion circuit 1, and is used to connect to the load device to obtain the power information of the load device. The power information refers to the power information of the load device. Exemplarily, after the communication interface circuit 2 is connected to the load device, the load device determines whether the current power is less than 100%, and generates power information. And the power information is output to the communication interface circuit 2 through the OTG function of the load device. So as to judge whether the load device is fully charged according to the power information.

[0041] As an example, the first chip 3 is connected to the communication interface circuit 2, and is used to output a first control signal according to the power information. Exemplarily, the load device outputs the power information to the first chip 3 through the OTG function. The first chip 3 determines that the current power of the load device is less than 100% based on the power information, and then outputs the first control signal as a high-level signal. If the current power of the load device is not less than 100%, the first control signal is output as a low-level signal.

[0042] As an example, the second chip 4 is connected to the first chip 3 and the power conversion circuit 1, and is used to receive the first control signal and output the second control signal. Exemplarily, the second control signal is a control signal corresponding to the first control signal. For example, the first control signal is a low-level signal, and the second control signal is also a low-level signal. For example, the first control signal is a high-level signal, and the second control signal is also a high-level signal. The switch circuit 5 is arranged between the power input terminal and the power conversion circuit 1, and is connected to the second chip 4, and is used to turn on or off according to the second control signal. Exemplarily, when the second control signal is a high-level signal, the switch circuit 5 is turned on, and the power circuit charges the load device normally. When the second control signal is a low-level signal, the switch circuit 5 is turned off, and the power circuit stops charging the load device, so that after the load device completes charging, the power circuit and the load device are disconnected, the loss of the power circuit is reduced, and at the same time, the aging of the device and the occurrence of faults caused by unstable grid voltage are reduced, and the safety during the charging process is ensured. Optionally, the switch circuit 5 may include a switch tube or a thyristor.

[0043] In this embodiment, the power supply circuit includes a power conversion circuit 1, a communication interface circuit 2, a first chip 3, a second chip 4 and a switch circuit 5; the power conversion circuit 1 is used to connect the power input end and perform power conversion on the electrical signal output from the power input end; the communication interface circuit 2 is connected to the power conversion circuit 1 and is used to connect the load device and obtain the power information of the load device; the first chip 3 is connected to the communication interface circuit 2 and is used to output a first control signal according to the power information; the second chip 4 is connected to the first chip 3 and the power conversion circuit 1 and is used to receive the first control signal and output the second control signal; the switch circuit 5 is arranged between the power input end and the power conversion circuit 1 and is connected to the second chip 4 and is used to be turned on or off according to the second control signal, so that the switch circuit 5 can disconnect the power circuit and the load device after the load device completes charging, thereby reducing the loss of the power circuit, and at the same time reducing the occurrence of faults caused by device aging and unstable grid voltage, thereby ensuring the safety of the charging process.

[0044] In one embodiment, the switching circuit 5 includes a first switching tube Q2; the first end of the first switching tube Q2 is connected to the power input end, the second end of the first switching tube Q2 is connected to the power conversion circuit 1, and the third end of the first switching tube Q2 is connected to the second chip 4.

[0045] As an example, the first switch tube Q2 is a field effect transistor or a bipolar transistor. The drain (emitter) of the first switch tube Q2 is connected to the power input terminal, the source (collector) of the first switch tube Q2 is connected to the power conversion circuit 1, and the gate (base) of the first switch tube Q2 is connected to the second chip 4.

[0046] In this embodiment, when the current power of the load device is less than 100%, the second control signal output by the second chip 4 is a high-level signal, driving the first switch tube Q2 to turn on and charge the load device. When the current power of the load device is not less than 100%, the second control signal output by the second chip 4 is a low-level signal, driving the first switch tube Q2 to turn off, disconnecting the power circuit and the load device, reducing the loss of the power circuit, and at the same time reducing the aging of the device and the occurrence of faults caused by unstable grid voltage, thereby ensuring the safety of the charging process.

[0047] In one embodiment, the power circuit further includes a first capacitor EC1, a first end of the first capacitor EC1 is connected to a connection node between the power conversion circuit 1 and a second end of the first switch tube Q2, and a second end of the first capacitor EC1 is grounded GND.

[0048] As an example, the first end of the first capacitor EC1 is connected to the connection node between the power conversion circuit 1 and the second end of the first switch tube Q2, and the second end of the first capacitor EC1 is grounded, which is used to absorb the large current when the first switch tube Q2 is turned on, so as to protect the connected load device and the power conversion circuit 1. It can be understood that the capacitance value of the first capacitor EC1 can be selected according to actual experience and is not limited here.

[0049] Furthermore, the power supply circuit also includes a rectifier circuit BD1, the first input terminal AC and the second input terminal AC of the rectifier circuit BD1 are respectively used to connect the neutral line and the live line of the power grid, the first output terminal V+ is connected to the power input terminal, and the second output terminal V- is grounded GND, which is used to convert the AC signal into a DC signal.

[0050] In one embodiment, the power supply circuit further includes a photoelectric coupler; the photoelectric coupler is connected to the first chip 3 and the second chip 4 and is used to transmit the first control signal.

[0051] In this embodiment, the photoelectric coupler is connected to the first chip 3 and the second chip 4 for transmitting the first control signal and isolating the first chip 3 from the second chip 4 .

[0052] In one embodiment, the photocoupler includes a light emitting diode U3A and a phototransistor U3B; the light emitting diode U3A is connected to the first chip 3 , and the phototransistor U3B is connected to the second chip 4 .

[0053] In this embodiment, when the load device needs to be charged, the first chip 3 outputs the first control signal as a high-level signal, drives the light-emitting diode U3A to work, and the phototransistor U3B senses that the light-emitting diode U3A is working and turns on, so that the second chip 4 outputs the second control signal to control the first switch tube Q2 to turn on, so that the power circuit can charge the load device normally. When the load device is fully charged, the first chip 3 outputs the first control signal as a low-level signal, the light-emitting diode U3A does not work, and the phototransistor U3B senses that the light-emitting diode U3A is not working and turns off, so that the second chip 4 outputs the second control signal to control the first switch tube Q2 to turn off, so as to disconnect the power input terminal and the load device, reduce the loss of the power circuit, and at the same time reduce the aging of the device and the occurrence of faults caused by unstable grid voltage, thereby ensuring the safety of the charging process.

[0054] In one embodiment, the power conversion circuit 1 includes a primary winding T1A, a main secondary winding T1B and an auxiliary secondary winding T1C; the first end of the primary winding T1A is used to connect to the power input terminal, and the second end of the primary winding T1A is grounded; the first end of the main secondary winding T1B is connected to the communication interface circuit 2, and the second end of the main secondary winding T1B is grounded; the first end of the auxiliary secondary winding T1C is connected to the second chip 4, and the second end of the auxiliary secondary winding T1C is grounded. Thus, power conversion is achieved by using the mutually coupled primary winding T1A, the main secondary winding T1B and the auxiliary secondary winding T1C.

[0055] As an example, the first power supply terminal Vin of the second chip 4 is connected to the power input terminal through the resistor R1 and the resistor R2, and the second power supply terminal Vcc of the second chip 4 is connected to the first end of the auxiliary secondary winding T1C through the diode D1. The resistor R5 and the resistor R6 are arranged in series between the first end and the ground terminal of the auxiliary secondary winding T1C, and the connection node of the resistor R5 and the resistor R6 is connected to the auxiliary winding voltage detection terminal Vsense of the second chip 4. The ground terminal GND of the second chip 4 is connected to the ground terminal, the signal feedback terminal FB of the second chip 4 is connected to the phototransistor U3B in the photocoupler, and the first control terminal Vg of the second chip 4 is connected to the third end of the first switch tube Q2. One end of the capacitor EC3 is connected to the cathode of the diode D1 and the second power supply terminal Vcc of the second chip 4, and the other end is grounded to prevent large current from damaging the second chip 4.

[0056] As an example, the first end of the main secondary winding T1B is also grounded via a capacitor EC2, and the capacitor EC2 is used for filtering. The second end of the main secondary winding T1B is grounded via a diode D2.

[0057] In one embodiment, the communication interface circuit 2 includes a USB-C interface, a power supply end of the USB-C is connected to the power conversion circuit 1 , and a communication end of the USB-C is connected to the first chip 3 .

[0058] As an example, the power supply end of USB-C includes B4 / A9 (VBUS) and A4 / B9 (VBUS). The communication end of USB-C includes B5 (CC2), B6 ​​(D+), A6 (D+), A7 (D-), B7 (D-) and A5 (CC1). It can be understood that the first chip 3 is provided with corresponding communication ends CC2, D+, D- and CC1.

[0059] In this embodiment, the communication interface circuit 2 includes a USB-C interface, the power supply end of the USB-C is connected to the power conversion circuit 1, and the communication end of the USB-C is connected to the first chip 3, so that the USB-C interface is used to realize the charging function and the acquisition of power information.

[0060] In one embodiment, the power supply circuit also includes a second switch tube Q3; the first end of the second switch tube Q3 is connected to the second end of the primary winding T1A, and the second end of the second switch tube Q3 is grounded through the first resistor R4; the third end of the second switch tube Q3 is connected to the first control end of the second chip 4; the first detection end of the second chip 4 is connected to the connection node between the second end of the second switch tube Q3 and the first resistor R4, for detecting an overcurrent protection signal.

[0061] As an example, the second switch tube Q3 is a field effect transistor or a bipolar transistor. The drain (emitter) of the second switch tube Q3 is connected to the second end of the primary winding T1A, the source (collector) of the second switch tube Q3 and the first resistor R4 are grounded, and the gate (base) of the second switch tube Q3 is connected to the second control terminal Gate of the second chip 4. The first detection terminal CS of the second chip 4 is connected to the connection node between the source (collector) of the second switch tube Q3 and the first resistor R4, and is used to detect the overcurrent protection signal, so that the second chip 4 outputs a PWM control signal to the second switch tube Q3 according to the overcurrent protection signal, and controls the power conversion circuit 1 to perform power conversion.

[0062] In one embodiment, the power supply circuit also includes a third switch tube Q1, a first end of the third switch tube Q1 is connected to the power conversion circuit 1, a second end of the third switch tube Q1 is connected to the communication interface circuit 2, and a third end of the third switch tube Q1 is connected to the first chip 3.

[0063] As an example, the second switch tube Q3 is a field effect transistor or a bipolar transistor. The drain (emitter) of the third switch tube Q1 is connected to the first end of the main secondary winding T1B, the source (collector) of the second switch tube Q3 is connected to the communication interface circuit 2, and the gate (base) of the second switch tube Q3 is connected to the third control terminal Vg of the first chip 3. Resistor R3 is between the ground terminal of the communication interface circuit 2 and the ground terminal GND1. The first detection terminal IS- and the second detection terminal IS+ of the second chip 4 are respectively connected to the two ends of the resistor R3 for detecting the charging current. The second chip 4 also includes a voltage output terminal Vout, a third power supply terminal Vin, a fourth power supply terminal VCC, a first comparison terminal CMP-I, a second comparison terminal CMP-V, an optical output terminal OPTO and a ground terminal GND. The optical output terminal OPTO and the ground terminal GND are connected in series to the light-emitting diode U3A in the optocoupler. It also includes a first input and output terminal GPIO1 and a second input and output terminal GPIO2. It is understandable that other types of second chips 4 may also be used. This example is only for illustration and does not limit the second chip 4. It is sufficient to ensure that the second chip 4 can communicate with the communication interface circuit 2 to obtain power information and control the light-emitting diode U3A to work according to the power information. Figure 1The second chip 4 is also provided with basic peripheral circuits, including capacitor C1, capacitor C2, resistor R7 and resistor R8, which will not be described in detail here.

[0064] This embodiment provides a switching power supply, including the above-mentioned power supply circuit.

[0065] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A power supply circuit, characterized in that: It includes a power conversion circuit, a communication interface circuit, a first chip, a second chip and a switch circuit; The power conversion circuit is used to connect to the power input terminal and perform power conversion on the electrical signal output by the power input terminal; The communication interface circuit is connected to the power conversion circuit and is used to connect to a load device to obtain power information of the load device; The first chip is connected to the communication interface circuit and is used to output a first control signal according to the power information; The second chip is connected to the first chip and the power conversion circuit, and is used to receive the first control signal and output a second control signal; The switch circuit is arranged between the power input terminal and the power conversion circuit and connected to the second chip, and is used for being turned on or off according to the second control signal.

2. The power supply circuit according to claim 1, characterized in that The switch circuit comprises a first switch tube; The first end of the first switch tube is connected to the power input end, the second end of the first switch tube is connected to the power conversion circuit, and the third end of the first switch tube is connected to the second chip.

3. The power supply circuit according to claim 2, characterized in that: The power supply circuit further includes a first capacitor, a first end of the first capacitor is connected to a connection node between the power conversion circuit and a second end of the first switch tube, and a second end of the first capacitor is grounded.

4. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes a photocoupler; The photoelectric coupler is connected to the first chip and the second chip, and is used for transmitting the first control signal.

5. The power supply circuit according to claim 4, characterized in that: The photoelectric coupler includes a light emitting diode and a phototransistor; The light emitting diode is connected to the first chip, and the phototransistor is connected to the second chip.

6. The power supply circuit according to claim 1, characterized in that: The power conversion circuit includes a primary winding, a main secondary winding and an auxiliary secondary winding; The first end of the primary winding is used to connect to the power input terminal, and the second end of the primary winding is grounded; The first end of the primary and secondary windings is connected to the communication interface circuit, and the second end of the primary and secondary windings is grounded; A first end of the auxiliary secondary winding is connected to the second chip, and a second end of the auxiliary secondary winding is grounded.

7. The power supply circuit according to claim 1, characterized in that: The communication interface circuit includes a USB-C interface, the power supply end of the USB-C is connected to the power conversion circuit, and the communication end of the USB-C is connected to the first chip.

8. The power supply circuit according to claim 6, characterized in that: The power supply circuit also includes a second switch tube; The first end of the second switch tube is connected to the second end of the primary winding, and the second end of the second switch tube is grounded through a first resistor; the third end of the second switch tube is connected to the first control end of the second chip; The first detection end of the second chip is connected to a connection node between the second end of the second switch tube and the first resistor, and is used to detect an overcurrent protection signal.

9. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes a third switch tube, a first end of the third switch tube is connected to the power conversion circuit, a second end of the third switch tube is connected to the communication interface circuit, and a third end of the third switch tube is connected to the first chip.

10. A switching power supply, characterized in that: Comprising the power supply circuit as claimed in any one of claims 1 to 9.

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