Protection circuit, power supply circuit and power supply circuit

Abstract

This application provides a protection circuit, a power supply circuit, and a power supply circuit. The protection circuit includes an impedance module, a first clamping module, a delay module, and a second clamping module. The first clamping module provides a first voltage below a first threshold based on a first power supply. The delay module outputs a delayed voltage after delaying the first voltage for a first duration. The second clamping module provides a power supply voltage below a second threshold based on the delayed voltage. The impedance module, when the first delay module is not in a clamping state, forms a second delay module with the first delay module to output a delayed voltage after delaying the first power supply for a second duration. When the voltage at the first power supply input terminal is below or above the first threshold, different delays can be applied. Even with higher voltage inputs, there is sufficient protection time to protect subsequent circuits, thus satisfying both a wide voltage range input and adequate protection duration requirements.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and more specifically, to a protection circuit, a power supply circuit, and a power source circuit. Background Technology

[0002] In wide-input switching power supply applications, cycle-by-cycle overcurrent protection is typically used to handle output short circuits. However, conventional switching power supply driver chips often have insufficient protection time under high-voltage input conditions during output short circuits, leading to high current stress on power devices and potentially causing device burnout. Utility Model Content

[0003] In order to overcome the technical problems mentioned in the above technical background, the embodiments of this application provide a protection circuit, a power supply circuit and a power source circuit to solve the problem of excessively short protection time when inputting a wide voltage range.

[0004] In a first aspect, embodiments of this application provide a protection circuit, the protection circuit including a power supply output terminal and a first power supply input terminal for connecting a first power supply, the protection circuit further including:

[0005] The impedance module has its first end connected to the first power supply input terminal;

[0006] A first clamping module is connected to the second end of the impedance module and is used to provide a first voltage of a first threshold based on the first power supply when in a clamped state, and to provide a first voltage below the first threshold based on the first power supply when not in a clamped state.

[0007] The first delay module is connected to the first clamping module and is used to output the delayed voltage through the output terminal after a delay of a first duration based on the first voltage.

[0008] The second clamping module is connected to the first delay module and the power supply output terminal, and is used to provide a power supply voltage below a second threshold to the power supply output terminal based on the delay voltage output by the first delay module;

[0009] Wherein, the impedance module is used to form a second delay module with the first delay module when the first clamping module is not in the clamping state, so as to output a delayed voltage after a second delay based on the first power supply; the second delay is longer than the first delay.

[0010] In some embodiments, the first clamping module includes a first Zener diode, the anode of which is grounded and the cathode of which is connected to the second terminal of the impedance module.

[0011] In some embodiments, the second clamping module includes a second Zener diode, the anode of which is grounded and the cathode of which is connected to the output terminal of the first delay module.

[0012] In some embodiments, the first delay module includes a first resistor and a first capacitor. A first end of the first resistor is connected to the first clamping module, a second end of the first resistor is connected to the second clamping module, and the first capacitor is connected between the second end of the first resistor and ground. The first capacitor shares a common ground with the first clamping module and the second clamping module.

[0013] Secondly, embodiments of this application provide a power supply circuit, the power supply circuit including a second power supply input terminal for connecting to a second power source and a protection circuit as described in any of the above claims, wherein the second power supply input terminal is connected to the output terminal of a first delay module of the protection circuit.

[0014] In some embodiments, the power supply circuit further includes a switching module and a current limiting module. The switching module is connected between the second terminal of the impedance module and the first clamping module. The first terminal of the current limiting module is connected to the first power supply input terminal, and the second terminal of the current limiting module is connected to the control terminal of the switching module.

[0015] In some embodiments, the power supply circuit further includes a shutdown module;

[0016] The shutdown module includes a first switching transistor and a second resistor; the first conducting terminal of the first switching transistor is also connected to the control terminal of the switching module, the second conducting terminal of the first switching transistor is grounded, and the control terminal of the first switching transistor is connected to the second power supply input terminal through the second resistor.

[0017] In some embodiments, the power supply circuit further includes

[0018] A first filtering voltage divider module, the first filtering voltage divider module being connected to the control terminal of the first switching transistor and grounded; and

[0019] The second filtering voltage divider module is connected to the control terminal of the switching module and grounded.

[0020] In some embodiments, the power supply circuit further includes a first unidirectional conduction module and a second unidirectional conduction module, wherein the first unidirectional conduction module is positively connected between the switch module and the first clamping module, and the second unidirectional conduction module is positively connected between the second power supply input terminal and the output terminal of the second clamping module.

[0021] Thirdly, embodiments of this application provide a power supply circuit, including a voltage conversion circuit and a power driver chip. The power driver chip is used to control the voltage conversion circuit to convert the input voltage and output it. The power supply circuit also includes a power supply circuit as described in any of the above claims. The second power supply input terminal of the power supply circuit is connected to the output terminal of the voltage conversion circuit. The first power supply input terminal of the power supply circuit is connected to the input terminal of the voltage conversion circuit. The power supply output terminal of the power supply circuit is connected to the operating voltage input pin of the power driver chip.

[0022] The beneficial effects of this application embodiment compared with the conventional technology are as follows: The protection circuit provided by this application embodiment includes a first power supply input terminal, a power supply output terminal, an impedance module, a first clamping module, a delay module, and a second clamping module. The first clamping module is used to provide a first voltage of a first threshold based on the first power supply when in a clamped state, and to provide a first voltage below the first threshold based on the first power supply when not in a clamped state. The delay module is used to output a delayed voltage after a first delay of a first duration based on the first voltage below the first threshold. The second clamping module is used to provide a power supply voltage below a second threshold to the power supply output terminal based on the delayed voltage output by the first delay module. The impedance module is used to form a second delay module with the first delay module when the first delay module is not in a clamped state, to output a delayed voltage after a second delay of a second duration based on the first power supply, where the second duration is longer than the first duration. In this embodiment, when the voltage at the first power supply input terminal is lower than the first threshold, the second delay module, composed of the impedance module and the first delay module, can be used to delay for a second duration before outputting a delayed voltage. When the voltage at the first power supply input terminal is higher than the first threshold, the voltage can be clamped by the first clamp module, and then the first delay module can be used to delay for a first duration before outputting a delayed voltage. Therefore, even with a higher voltage input, there is sufficient delay time to protect the subsequent circuit, that is, there is sufficient protection time to protect the subsequent circuit, thus satisfying both the wide voltage range input and the protection time requirements. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of a protection circuit provided in an embodiment of this application;

[0025] Figure 2A circuit diagram of a protection circuit provided in an embodiment of this application;

[0026] Figure 3 A schematic diagram of a power supply circuit provided in an embodiment of this application;

[0027] Figure 4 A schematic diagram of a power supply circuit provided in an embodiment of this application;

[0028] Figure 5 A schematic diagram of a power supply circuit provided in an embodiment of this application;

[0029] Figure 6 This is a circuit diagram of a power supply circuit provided in one embodiment of this application. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0032] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. It should be noted that, unless otherwise specified, different features in the embodiments of this application can be combined with each other.

[0033] For certain elements, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0034] In some types of switching power supplies, the principle of short-circuit protection using a power driver chip is as follows: During a short circuit, when the primary-side current of the flyback switching power supply controlled by the power driver chip continuously exceeds the peak current comparison point, the power driver chip sequentially blocks the drive output. The supply voltage of the power driver chip then slowly drops below the operating voltage, at which point the power driver chip completely stops output drive. Subsequently, the input voltage charges the startup capacitor through the startup resistor. When the supply voltage reaches the startup voltage of the power driver chip, the chip resumes operation. This process repeats, and the output hiccup cycle is determined by the charging network formed by the startup resistor and startup capacitor. The higher the input voltage, the shorter the output hiccup cycle, the greater the current stress on each power device, and the higher the temperature rise. Therefore, when the input voltage is high, the short-circuit protection duration is short, and short-circuit protection is more difficult to achieve. In some scenarios, the output hiccup cycle can be extended by increasing the startup resistor, but this may lead to problems with low-voltage input failure to start.

[0035] Therefore, to address the problem of insufficient protection time in the event of a short circuit in the output of a switching power supply, a protection circuit is provided that can meet the requirements for protection duration while satisfying a wide voltage range input.

[0036] Please see Figure 1 One embodiment of this application provides a protection circuit, which includes a power supply output terminal 101 and a first power supply input terminal 102 for connecting a first power supply Vin1. The protection circuit also includes an impedance module 110, a first clamping module 120, a first delay module 130 and a second clamping module 140.

[0037] The first terminal of the impedance module 110 is connected to the first power supply input terminal 102. The first clamping module 120 is connected to the second terminal of the impedance module 110. The first clamping module 120 is used to provide a first voltage of a first threshold based on the first power supply Vin1 when in a clamped state, and to provide a first voltage below the first threshold based on the first power supply Vin1 when not in a clamped state. The first delay module 130 is connected to the first clamping module 120 and is used to output a delayed voltage through the output terminal after a first delay based on the first voltage. The second clamping module 140 is connected to the first delay module 130 and the power supply output terminal 101 and is used to provide a power supply voltage Vout below a second threshold to the power supply output terminal 101 based on the delayed voltage output by the first delay module 130. The impedance module 110 is used to form a second delay module 150 with the first delay module 130 when the first clamping module 120 is not in a clamped state, to output a delayed voltage after a second delay based on the first power supply Vin1; the second delay is longer than the first delay. When the first clamping module 120 is not in the clamping state, it does not function and has no effect on the circuit.

[0038] In this embodiment, when the voltage input to the first power supply input terminal 102 is lower than the first threshold, the second delay module 150, composed of the impedance module 110 and the first delay module 130, can be used to delay for a second duration before outputting a delayed voltage. Conversely, when the voltage input to the first power supply input terminal 102 is higher than the first threshold, it can be clamped by the first clamping module 120 and then delayed for a first duration by the first delay module 130 before outputting a delayed voltage. Therefore, when the protection circuit supplies power to the power supply pins of the power driver chip 200 of the switching power supply, even if the switching power supply has a high voltage input, the first clamping module 120 can clamp it to a first voltage lower than that input voltage. This ensures that the first voltage, after being delayed by the first delay module 130, has sufficient delay time to protect the subsequent circuits, thus providing sufficient protection time for the subsequent circuits. This satisfies both the wide voltage range input requirements and the adequate protection time.

[0039] In some embodiments, such as Figure 2 As shown, the impedance module 110 includes a start-up resistor R. start In some embodiments, the impedance module 110 includes a start-up resistor R. start and filter capacitors.

[0040] Please see Figure 2 In some embodiments, the first clamping module 120 includes a first Zener diode ZD1, with its anode grounded and its cathode connected to the second terminal of the impedance module 110. In some embodiments, the second clamping module 140 includes a second Zener diode ZD2, with its anode grounded and its cathode connected to the output terminal of the first delay module 130. The second clamping module 140 is mainly used to regulate the output supply voltage Vout to prevent excessively high supply voltage Vout from damaging subsequent circuits.

[0041] It is understood that the breakdown voltage (i.e., the regulated voltage) of the first Zener diode ZD1 corresponds to the first threshold voltage, and the breakdown voltage of the second Zener diode ZD2 corresponds to the second threshold voltage. In an alternative embodiment, a TVS (Transient Voltage Suppressor) diode can be used to replace the Zener diode. The clamped state described above refers to the conducting state of the Zener diode, and its cathode voltage serves as the corresponding threshold voltage. When not in the clamped state, the Zener diode is in the non-conducting state and does not function.

[0042] For example, the first threshold is 33V, and the second threshold is 15V. When the first supply voltage provided by the first power supply Vin1 is lower than 33V, the first Zener diode ZD1 does not function, and directly outputs a first voltage lower than 33V to (that is, the first power supply Vin1 passes through the start-up resistor R). startThe first delay module 130 (after the voltage) is used to adjust the first delay period. When the first supply voltage is higher than 33V, the first Zener diode ZD1 breaks down, and the first Zener diode ZD1 regulates and outputs a first voltage of 33V to the first delay module 130. After adjusting the first delay of the first delay module 130, the voltage is output through the power supply output terminal 101. That is, when the input voltage of the first power supply Vin1 is high, it can be clamped to a first threshold voltage lower than the current input voltage, such as 33V, by the first Zener diode ZD1. Therefore, when using the first delay module 130 for delay, the delay time can be extended to avoid the delay time being too short when the input voltage of the first power supply Vin1 is high, thus failing to meet the delay protection requirements. Therefore, when the above protection circuit is applied to the switching power supply, the hiccup cycle of the switching power supply can be adjusted.

[0043] Please see Figure 2 In some embodiments, the first delay module 130 includes a first resistor R1 and a first capacitor C1. A first end of the first resistor R1 is connected to a first clamping module 120, and a second end of the first resistor R1 is connected to a second clamping module 140. The first capacitor C1 is connected between the second end of the first resistor R1 and ground, and the first capacitor C1 shares a common ground with both the first clamping module 120 and the second clamping module 140. It is understood that the delay duration can be adjusted by changing the resistance value of the first resistor R1 and the capacitance value of the first capacitor C1.

[0044] Please see Figure 3 An embodiment of this application also discloses a power supply circuit, which includes a second power supply input terminal 160 for connecting a second power supply Vin2 and a protection circuit in any of the above embodiments. The second power supply input terminal 160 is connected to the output terminal of the first delay module 130.

[0045] When the power supply circuit is applied to the switching power supply, the second power supply Vin2 can be taken from the switching power supply itself, that is, the output terminal of the switching power supply is used as the second power supply input terminal 160 to provide the second power supply Vin2 to the power supply circuit.

[0046] In the event of a short circuit at the output of the switching power supply, the output of the second power supply Vin2 will be stopped through short-circuit protection. When the switching power supply needs to restart, it will supply power to the power driver chip 200 using the first power supply voltage provided by the first power supply Vin1 at the first power supply input terminal. Specifically, when the voltage at the first power supply input terminal 102 is lower than a first threshold, a second delay module 150, composed of the impedance module 110 and the first delay module 130, can be used to delay for a second duration before outputting a delayed voltage. Conversely, when the voltage at the first power supply input terminal 102 is higher than the first threshold, it can be clamped by the first clamping module 120 and then delayed for a first duration using the first delay module 130 before outputting a delayed voltage. Therefore, when the power supply circuit supplies power to the power driver chip 200 of the switching power supply, even with a high input voltage, there is sufficient delay time to protect the downstream circuitry, thus satisfying both a wide voltage range input and adequate protection time requirements.

[0047] Please see Figure 4 In some embodiments, the power supply circuit further includes a switching module 170 and a current limiting module 180. The switching module 170 is connected between the second terminal of the impedance module 110 and the first clamping module 120. The first terminal of the current limiting module 180 is connected to the first power supply input terminal 102, and the second terminal of the current limiting module 180 is connected to the control terminal of the switching module 170. Specifically, the current limiting module 180 provides a bias voltage to the control terminal of the switching module 170 based on the first power supply voltage when the first power supply input terminal 102 is powered on, thereby controlling the switching module 170 to conduct. This allows the first power supply voltage to be input to the first clamping module 120 through the impedance module 110, ultimately supplying power to the power supply output terminal 101. When the first power supply Vin1 is less than a certain voltage value, the current limiting module 180 cannot provide sufficient bias voltage to enable the switching module 170 to conduct. In this case, the first power supply Vin1 cannot supply power to subsequent circuits through the impedance module 110 and the switching module 170.

[0048] For example, the switching module 170 includes an N-channel MOSFET, such as... Figure 6 As shown. The gate, source, and drain of the MOSFET serve as the control terminal, input terminal, and output terminal of the switching module 170, respectively. The current limiting module 180 includes one or more resistors connected in series. For example, the current limiting module 180 includes a current limiting resistor R5, which can be formed by one or more series resistors.

[0049] Please see Figure 5In some embodiments, the power supply circuit further includes a shutdown module 190. The control terminal of the shutdown module 190 is connected to the second power supply input terminal 160, the first terminal of the shutdown module 190 is connected to the control terminal of the switch module 170, and the second terminal of the shutdown module 190 is grounded. The shutdown module 190 is used to turn on when the input voltage input to the second power supply input terminal 160 is greater than the conduction voltage value, so as to control the switch module 170 to turn off, thereby stopping the power supply input to the first power supply input terminal 102. The power supply circuit outputs the power supply voltage Vout to the power supply output terminal 101 through the second clamping module 140 from the second power supply input terminal 160. When the above power supply circuit is applied to a switching power supply, the second power supply input terminal 160 is connected to the output terminal of the switching power supply. When the switching power supply starts and has output, the shutdown module 190 is turned on to control the switch module 170 to turn off. The power supply circuit stops receiving input voltage from the first power supply input terminal 102, and instead receives the output voltage of the switching power supply from the second power supply input terminal 160 as the power supply to power the switching power supply chip.

[0050] Please see Figure 6 In some embodiments, the shutdown module 190 includes a first switch Q1 and a second resistor R2. The first conducting terminal of the first switch Q1 is also connected to the control terminal of the switch module 170, the second conducting terminal of the first switch Q1 is grounded, and the control terminal of the first switch Q1 is connected to the second power supply input terminal 160 through the second resistor R2.

[0051] Among them, the first switch Q1 is an N-channel MOSFET, and the gate, source and drain of the MOSFET serve as the control terminal, the first conduction terminal and the second conduction terminal of the first switch Q1, respectively.

[0052] Please see Figure 6 In some embodiments, the power supply circuit further includes a third Zener diode ZD3, the cathode of which is connected to the control terminal of the switching module 170, and the anode is grounded. The third Zener diode ZD3 is used to stabilize the voltage at the control terminal of the switching module 170.

[0053] Please see Figure 6 In some embodiments, the power supply circuit further includes a first filtering voltage divider module 210 and a second filtering voltage divider module 220. The first filtering voltage divider module 210 is connected to and grounded to the control terminal of the first switching transistor Q1, and filters and appropriately divides the voltage input to the second power supply input terminal 160. The second filtering voltage divider module 220 is connected to and grounded to the control terminal of the switching module 170, and filters and appropriately divides the voltage input to the first power supply input terminal 102.

[0054] In some embodiments, the first filter voltage divider module 210 includes a first filter capacitor C2 and a first voltage divider resistor R3. The first filter capacitor C2 is connected between the control terminal of the first switching transistor Q1 and ground, and the first voltage divider resistor R3 is connected in parallel with the first filter capacitor C2. The first filter capacitor C2 is used to filter the input of the second power supply input terminal 160 and stabilize the voltage at the control terminal of the first switching transistor Q1. The first voltage divider resistor R3 and the second resistor R2 form a first voltage divider circuit to appropriately divide the input of the second power supply input terminal 160 to drive the first switching transistor Q1. It can be understood that the second resistor R2 plays a role in current limiting and voltage division.

[0055] In some embodiments, the second filter voltage divider module 220 includes a second filter capacitor C3 and a second voltage divider resistor R4. The second filter capacitor C3 is connected between the control terminal and the output terminal of the switching module 170, and the second voltage divider resistor R4 is connected in parallel with the second filter capacitor C3. The second filter capacitor C3 is used to filter the output of the current limiting module 180 and stabilize the voltage at the control terminal of the switching module 170. The second voltage divider resistor R4 and the current limiting module 180 form a voltage divider circuit, thereby appropriately dividing the input of the first power supply input terminal 102 to drive the switching module 170. It can be understood that the current limiting module 180 plays the role of current limiting and voltage dividing.

[0056] Please see Figure 6 In some embodiments, the power supply circuit further includes a first unidirectional conduction module D1 and a second unidirectional conduction module D2. The first unidirectional conduction module D1 is positively connected between the switch module 170 and the first clamping module 120, and the second unidirectional conduction module D2 is positively connected between the second power supply input terminal 160 and the output terminal of the second clamping module 140.

[0057] The first unidirectional conduction module D1 and the second unidirectional conduction module D2 are, for example, diodes, used to prevent the electrical signals between the first power supply input terminal 102 and the second power supply input terminal 160 from flowing back to each other.

[0058] Please see Figure 5 and Figure 6 One embodiment of this application also provides a power supply circuit, which includes a voltage conversion circuit (not shown) and a power driver chip 200. The power driver chip 200 is used to control the voltage conversion circuit to convert the input voltage and output it. The power supply circuit also includes a power supply circuit as described in any of the above embodiments. The second power supply input terminal 160 of the power supply circuit is connected to the output terminal of the voltage conversion circuit. The first power supply input terminal 102 of the power supply circuit is connected to the input terminal of the voltage conversion circuit. The power supply output terminal 101 of the power supply circuit is connected to the operating voltage input pin of the power driver chip 200.

[0059] The voltage conversion circuit includes non-isolated switching power supply circuits, such as boost, buck, or boost-buck circuits; it may also include isolated switching power supply circuits, such as single-ended flyback converters; or other forms of voltage conversion circuits.

[0060] Taking a flyback converter as an example, before the output of the voltage conversion circuit (which serves as the second power supply Vin2) is established, the power supply chip 200 is generally powered by the input voltage of the voltage conversion circuit (i.e., the first power supply Vin1) through the start-up resistor R. start Provided. After the voltage (e.g., 12V) of the second power supply Vin2 is established, the startup resistor R is disconnected through the first switching transistor Q1. start Reduce losses.

[0061] The switching power supply in this embodiment, based on the aforementioned protection circuit or power supply circuit, can solve the problem of excessively long short-circuit protection time under high voltage and wide input conditions, while simultaneously reducing the startup power consumption of the switching power supply. Specifically, through the reasonable circuit principle design and key component selection of the impedance module 110, the first clamping module 120, the first delay module 130, and the second clamping module 140, the hiccup time of the power driver chip 200 is effectively extended while meeting the requirements of high voltage and wide input range. This achieves reliable short-circuit protection under high voltage and wide range, and solves the problem of failure to start under low voltage. The power driver chip 200 can achieve effective short-circuit protection, the main power transistor of the switching power supply has low stress and low temperature, and the no-load loss of the switching power supply is significantly reduced, verifying the feasibility and effectiveness of the solution. This solution has broad application prospects and can be extended to other similar circuits to improve circuit stability and reliability. The cost increase of the solution is reasonable and has good cost performance.

[0062] It should be noted that all or part of the above embodiments provided in this application (e.g., part or all of any feature) can be arbitrarily combined or combined with each other.

[0063] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A protection circuit, characterized by, The protection circuit includes a power supply output terminal and a first power supply input terminal for connecting to a first power supply. The protection circuit also includes: The impedance module has its first end connected to the first power supply input terminal; A first clamping module is connected to the second end of the impedance module and is used to provide a first voltage of a first threshold based on the first power supply when in a clamped state, and to provide a first voltage below the first threshold based on the first power supply when not in a clamped state. The first delay module is connected to the first clamping module and is used to output the delayed voltage through the output terminal after a delay of a first duration based on the first voltage. The second clamping module is connected to the first delay module and the power supply output terminal, and is used to provide a power supply voltage below a second threshold to the power supply output terminal based on the delay voltage output by the first delay module; Wherein, the impedance module is used to form a second delay module with the first delay module when the first clamping module is not in the clamping state, so as to output a delayed voltage after a second delay based on the first power supply; the second delay is longer than the first delay.

2. The protection circuit of claim 1, wherein, The first clamping module includes a first Zener diode, the anode of which is grounded and the cathode of which is connected to the second terminal of the impedance module.

3. The protection circuit of claim 1, wherein, The second clamping module includes a second Zener diode, the anode of which is grounded and the cathode of which is connected to the output terminal of the first delay module.

4. Protection circuit according to any one of claims 1 to 3, characterized in that The first delay module includes a first resistor and a first capacitor. The first end of the first resistor is connected to the first clamping module, the second end of the first resistor is connected to the second clamping module, and the first capacitor is connected between the second end of the first resistor and ground. The first capacitor shares a common ground with the first clamping module and the second clamping module.

5. A power supply circuit, characterized by comprising: The power supply circuit includes a second power supply input terminal for connecting to a second power source and a protection circuit as described in any one of claims 1 to 4, wherein the second power supply input terminal is connected to the output terminal of the first delay module of the protection circuit.

6. The power supply circuit of claim 5, wherein, The power supply circuit also includes a switching module and a current limiting module. The switching module is connected between the second terminal of the impedance module and the first clamping module. The first terminal of the current limiting module is connected to the first power supply input terminal, and the second terminal of the current limiting module is connected to the control terminal of the switching module.

7. The power supply circuit of claim 6, wherein, The power supply circuit also includes a shutdown module; The shutdown module includes a first switching transistor and a second resistor; the first conducting terminal of the first switching transistor is connected to the control terminal of the switching module, the second conducting terminal of the first switching transistor is grounded, and the control terminal of the first switching transistor is connected to the second power supply input terminal through the second resistor.

8. The power supply circuit of claim 7, wherein, The power supply circuit also includes: A first filtering voltage divider module, the first filtering voltage divider module being connected to the control terminal of the first switching transistor and grounded; and The second filtering voltage divider module is connected to the control terminal of the switching module and grounded.

9. A power supply circuit as claimed in any one of claims 6 to 8, characterized in that, The power supply circuit further includes a first unidirectional conduction module and a second unidirectional conduction module. The first unidirectional conduction module is positively connected between the switch module and the first clamping module, and the second unidirectional conduction module is positively connected between the second power supply input terminal and the output terminal of the second clamping module.

10. A power supply circuit, characterized by comprising: The device includes a voltage conversion circuit and a power driver chip. The power driver chip is used to control the voltage conversion circuit to convert the input voltage and output it. The power circuit also includes a power supply circuit as described in any one of claims 5 to 9. The second power supply input terminal of the power supply circuit is connected to the output terminal of the voltage conversion circuit. The first power supply input terminal of the power supply circuit is connected to the input terminal of the voltage conversion circuit. The power supply output terminal of the power supply circuit is connected to the operating voltage input pin of the power driver chip.

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