An overvoltage protection circuit

Abstract

This utility model discloses an overvoltage protection circuit electrically connected between a power supply module and a level conversion circuit. It includes a third diode, a second transistor, a third switching transistor, an eighth switching transistor, a first resistor, a control unit, and series-connected fifth and tenth resistors, as well as series-connected sixth and twelfth resistors. The power supply module is connected to the series node of the fifth and tenth resistors via the third switching transistor and the first resistor. The base of the second transistor is connected to the series node of the fifth and tenth resistors. The power supply module is connected to the emitter of the second transistor and the sixth resistor. The power supply module is connected to the twelfth resistor via the control unit. The power supply module is connected to the level conversion circuit via the eighth switching transistor. The control terminals of the eighth and third switching transistors, as well as the collector of the second transistor, are connected to the series node of the sixth and twelfth resistors. The power supply module is connected to the cathode of the third diode (with its anode grounded) via the fifth and tenth resistors.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and in particular to an overvoltage protection circuit. Background Technology

[0002] In circuit design, overvoltage protection is an important consideration. It refers to a measure that protects the circuit by disconnecting the power supply or reducing the voltage of the controlled equipment when the voltage of the protected line exceeds a predetermined maximum value. Existing overvoltage protection circuits use the same voltage threshold for both protection and recovery. When the power supply voltage is unstable, repeated switching on and off can occur, failing to effectively disconnect the power supply and leading to protection failure. Utility Model Content

[0003] The purpose of this invention is to provide an overvoltage protection circuit so that the protection voltage threshold is higher than the recovery voltage threshold, thereby preventing the protection from failing due to repeated switching on and off when the power supply voltage is unstable.

[0004] To solve the above-mentioned technical problems, this utility model provides an overvoltage protection circuit. The overvoltage protection circuit is electrically connected between the power supply module and the level conversion circuit. The overvoltage protection circuit includes a third diode, a second transistor, a third switching transistor, an eighth switching transistor, a first resistor, a fifth resistor, a sixth resistor, a tenth resistor, a twelfth resistor, and a control unit. The control unit controls the operation of the eighth and third switching transistors. The fifth and tenth resistors are connected in series. The power supply module is connected to the series node of the fifth and tenth resistors via the third switching transistor and the first resistor. The base of the second transistor is electrically connected to the series node of the fifth and tenth resistors. At the node, the power supply module is connected to the emitter of the second transistor, the sixth resistor is connected in series with the twelfth resistor, the power supply module is connected to the sixth resistor, the power supply module is connected to the twelfth resistor through the control unit, the power supply module is connected to the level conversion circuit through the eighth switch, the control terminal of the eighth switch, the collector of the second transistor, and the control terminal of the third switch are all electrically connected to the series node of the sixth and twelfth resistors, so that the second transistor is connected in parallel with the sixth resistor, the power supply module is connected to the cathode of the third diode after the fifth and tenth resistors, and the anode of the third diode is grounded.

[0005] The further technical solution is as follows: the eighth switch is a PMOS transistor, the source of the eighth switch is connected to the power supply module, the drain of the eighth switch is connected to the level conversion circuit, and the gate of the eighth switch is electrically connected to the series node of the sixth resistor and the twelfth resistor.

[0006] The further technical solution is as follows: the third switching transistor is a PMOS transistor, the source of the third switching transistor is connected to the power supply module, the drain of the third switching transistor is connected to the first end of the first resistor, the second end of the first resistor is electrically connected to the series node of the fifth resistor and the tenth resistor, and the gate of the third switching transistor is electrically connected to the series node of the sixth resistor and the twelfth resistor.

[0007] A further technical solution is as follows: the overvoltage protection circuit further includes a fourteenth diode, the anode of the fourteenth diode is connected to the series node of the sixth resistor and the twelfth resistor, and the cathode of the fourteenth diode is connected to the power supply module so that the fourteenth diode is connected in parallel with the sixth resistor.

[0008] The further technical solution is that both the third diode and the fourteenth diode are Zener diodes.

[0009] The further technical solution is as follows: the control unit includes an eighth resistor, a ninth resistor, and a twenty-fourth transistor. The eighth resistor is connected in series with the ninth resistor. The power supply module is connected to the eighth resistor. The ninth resistor is grounded. The base of the twenty-fourth transistor is electrically connected to the series node of the eighth resistor and the ninth resistor. The collector of the twenty-fourth transistor is connected to the twelfth resistor. The emitter of the twenty-fourth transistor is grounded.

[0010] The further technical solution is as follows: the 24th transistor is an NPN transistor, and the 2nd transistor is a PNP transistor.

[0011] The further technical solution is as follows: the control unit also includes an eleventh grounding capacitor, which is electrically connected to the series node of the eighth resistor and the ninth resistor.

[0012] The further technical solution is as follows: the overvoltage protection circuit also includes a fuse and a tenth diode, and the power supply module is connected to the eighth switching transistor via the fuse and the tenth diode.

[0013] The further technical solution is as follows: the overvoltage protection circuit further includes a second grounding capacitor and a fifteenth capacitor. The second grounding capacitor is connected to the power supply module. One end of the fifteenth capacitor is electrically connected to the series node of the sixth resistor and the twelfth resistor. The other end of the fifteenth capacitor is connected to the power supply module.

[0014] The beneficial technical effects of this utility model are as follows: The overvoltage protection circuit of this utility model is electrically connected between the power supply module and the level conversion circuit. When the supply voltage of the power supply module is higher than the preset protection voltage threshold, the power supply module disconnects the power supply to the level conversion circuit, thereby protecting the level conversion circuit. The overvoltage protection circuit is configured with a third diode, a second transistor, and a fifth and tenth resistor connected in series. When the third diode is conducting and the second transistor is conducting, current limiting and voltage division are achieved, which together constitute the setting and protection circuit for the protection voltage threshold. The circuit is further configured with a third switch connected to the power supply module, a first resistor connected at both ends to the third switch and the tenth resistor respectively, an eighth switch electrically connected between the power supply module and the level conversion circuit, a sixth and twelfth resistor connected in series, and a control unit connected to the twelfth resistor. The power supply module is connected to the sixth resistor and the control unit to ensure that the power supply... A circuit is formed between the power module, the sixth resistor, the twelfth resistor, and the control unit. The control terminals of the third and eighth switching transistors are electrically connected to the series node of the sixth and twelfth resistors. The control unit controls the on / off state of the third and eighth switching transistors to control the power supply from the power module to the level conversion circuit. The first resistor is connected to the power module through the third switching transistor and electrically connected to the series node of the fifth and tenth resistors, so as to be connected to the base of the second transistor. The base of the second transistor is electrically connected to the series node of the fifth and tenth resistors to realize feedback control of the second transistor based on the on / off state of the eighth switching transistor. This results in a difference between the protection voltage threshold and the recovery voltage threshold, realizing the hysteresis function. The protection voltage threshold is higher than the recovery voltage threshold to prevent the protection from failing due to repeated on / off switching when the power supply voltage is unstable. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The circuit diagram of the overvoltage protection circuit provided by this utility model. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0018] Please see Figure 1 , Figure 1 This is a circuit diagram of the overvoltage protection circuit provided by this utility model. The overvoltage protection circuit 10 is electrically connected between the power supply module and the level conversion circuit. The overvoltage protection circuit 10 includes a third diode D3, a second transistor T2, a third switch T3, an eighth switch T8, a first resistor R1, a fifth resistor R5, a sixth resistor R6, a tenth resistor R10, a twelfth resistor R12, and a control unit 11. The control unit 11 is used to control the operation of the eighth switch T8 and the third switch T3. The fifth resistor R5 and the tenth resistor R10 are connected in series. The power supply module is connected to the series node of the fifth resistor R5 and the tenth resistor R10 through the third switch T3 and the first resistor R1. The base of the second transistor is electrically connected to the series connection of the fifth resistor and the tenth resistor. At the node, the power supply module is connected to the emitter of the second transistor T2. The sixth resistor R6 and the twelfth resistor R12 are connected in series. The power supply module is connected to the sixth resistor R6. The power supply module is connected to the twelfth resistor R12 through the control unit 11. The power supply module is connected to the level conversion circuit through the eighth switch T8. The control terminal of the eighth switch T8, the collector of the second transistor T2, and the control terminal of the third switch T3 are all electrically connected to the series node of the sixth resistor R6 and the twelfth resistor R12, so that the second transistor T2 and the sixth resistor R6 are connected in parallel. The power supply module is connected to the cathode of the third diode D3 through the fifth resistor R5 and the tenth resistor R10. The anode of the third diode D3 is grounded.

[0019] During normal operation, the power supply voltage output by the power supply module is less than the protection voltage threshold, which should be less than the limit input voltage of the level conversion circuit. The resistance of the fifth resistor R5 is greater than that of the tenth resistor R10, which in turn is greater than that of the first resistor R1. The input terminal of the overvoltage protection circuit 10 is connected to the output terminal PW+ of the power supply module. The power supply module can be a power source. The output terminal of the overvoltage protection circuit 10 is connected to the input terminal CH of the level conversion circuit. By setting the overvoltage protection circuit 10, the power supply voltage input to the level conversion circuit is monitored, and the power supply is disconnected when the voltage is too high to protect the level conversion circuit. By cooperating with the third switch T3 and the eighth switch T8, when the power supply voltage output by the power supply module is too high, the connection between the power supply module and the level conversion circuit can be disconnected to protect the level conversion circuit. The power supply feedback from the power supply module to the base of the second transistor T2 is also disconnected. The overvoltage protection circuit 10 is electrically connected between the power supply module and the level conversion circuit. When the power supply voltage of the power supply module exceeds a preset protection voltage threshold, the power supply from the power supply module to the level conversion circuit is disconnected, thus protecting the level conversion circuit. The overvoltage protection circuit 10 utilizes a third diode... D3, the second transistor T2, and the series-connected fifth resistor R5 and tenth resistor R10 together form a current-limiting voltage divider when the third diode D3 is conducting and the second transistor T2 is conducting. This together constitutes the protection voltage threshold setting and protection circuit. This is achieved by setting the third switch T3 connected to the power supply module, the first resistor R1 connected to the third switch T3 and the tenth resistor R10 respectively, the eighth switch T8 electrically connected between the power supply module and the level conversion circuit, and the series-connected sixth resistor R6 and twelfth resistor R12. The control unit 11 is connected to the power supply module, and the power supply module is connected to the sixth resistor R6 and the control unit 11 to form a loop between the power supply module, the sixth resistor R6, the twelfth resistor R12 and the control unit 11. The control terminals of the third switch T3 and the eighth switch T8 are electrically connected to the series node of the sixth resistor R6 and the twelfth resistor R12, so that the control unit 11 controls the on and off of the third switch T3 and the eighth switch T8 to realize the on and off control of the power supply module to the level conversion circuit. The first resistor R1 is connected to the power supply module through the third switch T3. It is electrically connected to the series node of the fifth resistor R5 and the tenth resistor R10, and connected to the base of the second transistor T2. The base of the second transistor T2 is also electrically connected to the series node of the fifth resistor R5 and the tenth resistor R10. This allows feedback control of the second transistor T2 based on the on / off state of the eighth switch T8, so that there is a difference between the protection voltage threshold and the recovery voltage threshold, realizing the hysteresis function. Furthermore, the protection voltage threshold is higher than the recovery voltage threshold, preventing the problem of repeated switching when the power supply voltage is unstable, which would lead to the failure of protection due to the inability to effectively disconnect the power supply.

[0020] Preferably, in this embodiment, the resistance of the fifth resistor R5 is 47KΩ, the resistance of the tenth resistor R10 is 20KΩ, and the resistance of the first resistor is 10KΩ. The fifth resistor R5 and the tenth resistor R10 are connected in series for current limiting and voltage division. When the third diode D3 is regulated and conducting, and the base and emitter of the second transistor T2 are connected, current limiting and voltage division are achieved, together forming the protection voltage threshold and protecting the circuit. Different protection voltage thresholds and hysteresis voltage values ​​can be set by adjusting the resistance values ​​of the first resistor R1, the fifth resistor R5, and the tenth resistor R10, as well as the Zener voltage of the third diode D3. In this embodiment, the protection voltage threshold can be 42.9V, and the recovery voltage value can be 41.3V.

[0021] Specifically, in this embodiment, the eighth switch T8 is a PMOS transistor, the source of the eighth switch T8 is connected to the power supply module, the drain of the eighth switch T8 is connected to the level conversion circuit, and the gate of the eighth switch T8 is electrically connected to the series node of the sixth resistor R6 and the twelfth resistor R12.

[0022] Specifically, the third switch T3 is a PMOS transistor. The source of the third switch T3 is connected to the power supply module, the drain of the third switch T3 is connected to the first end of the first resistor R1, the second end of the first resistor R1 is electrically connected to the series node of the fifth resistor R5 and the tenth resistor R10, and the gate of the third switch T3 is electrically connected to the series node of the sixth resistor R6 and the twelfth resistor R12.

[0023] Preferably, both the third switch T3 and the eighth switch T8 can be PMOS transistors of type AGMH20P15. The PMOS transistor of type AGMH20P15 has high source and drain withstand voltage, and the input impedance of this type of PMOS transistor is high while the on-resistance is low, resulting in low power dissipation and low leakage current. When the voltage difference between the gate and source of the third switch T3 is less than -2.6V, the source and drain of the third switch T3 are connected, and the third switch T3 is turned on; when the voltage difference between the gate and source of the third switch T3 is greater than -2.6V, the source and drain of the third switch T3 are turned off, and the third switch T3 is turned off. When the voltage difference between the gate and source of the eighth switch T8 is less than -2.6V, the source and drain of the eighth switch T8 are connected, and the eighth switch T8 is turned on; when the voltage difference between the gate and source of the eighth switch T8 is greater than -2.6V, the source and drain of the eighth switch T8 are turned off, and the eighth switch T8 is turned off.

[0024] Preferably, the overvoltage protection circuit 11 further includes a fourteenth diode D14, the anode of which is connected to the series node of the sixth resistor R6 and the twelfth resistor R12, and the cathode of which is connected to the power supply module, so that the fourteenth diode D14 is connected in parallel with the sixth resistor R6.

[0025] Preferably, the fourteenth diode D14 is a Zener diode, used to stabilize the voltage divided by the supply voltage through the sixth resistor R6 and the twelfth resistor R12 to a voltage value lower than the limit voltage difference between the source and gate of the eighth switch T8 and the third switch T3, so as to protect the eighth switch T8 and the third switch T3.

[0026] Specifically, the third diode D3 is a Zener diode. Preferably, in this embodiment, the clamping voltage of the third diode D3 can be 39V. When the voltage across the third diode D3 is higher than 39V, the third diode D3 is regulated and conducts, so that the voltage drop across the third diode D3 is stabilized at 39V. When the voltage across the third diode D3 is lower than 39V, the third diode D3 is not conducting.

[0027] Specifically, the control unit 11 includes an eighth resistor R8, a ninth resistor R9, and a twenty-fourth transistor T24. The eighth resistor R8 and the ninth resistor R9 are connected in series. The power supply module is connected to the eighth resistor R8, and the ninth resistor R9 is grounded. The base of the twenty-fourth transistor T24 is electrically connected to the series connection point of the eighth resistor R8 and the ninth resistor R9. The collector of the twenty-fourth transistor T24 is connected to the twelfth resistor R12, and the emitter of the twenty-fourth transistor T24 is grounded. The twenty-fourth transistor T24 can be used to turn on the eighth switch T8 and the third switch T3 when the input voltage is higher than 6V, so that the level conversion circuit can be powered. The eighth resistor R8 and the ninth resistor R9 are connected in series to limit current and divide voltage, thereby protecting the twenty-fourth transistor T24.

[0028] Specifically, the second fourteenth transistor T24 is an NPN transistor, and the second transistor T2 is a PNP transistor. Preferably, the second fourteenth transistor T24 can be an NPN transistor of model MMBTA42, and the second transistor T2 can be a PNP transistor of model MMBTA92. When the voltage difference between the emitter and base of the second transistor T2 is higher than 0.7V, the emitter and collector of the second transistor T2 are connected, and the second transistor T2 is turned on. When the voltage difference between the emitter and base of the second transistor T2 is lower than 0.7V, the emitter and collector of the second transistor T2 are turned off, and the second transistor T2 is turned off. When the voltage difference between the base and emitter of the 24th transistor T24 is higher than 0.7V, the collector and emitter of the 24th transistor T24 are connected, and the 24th transistor T24 is turned on. When the voltage difference between the base and emitter of the 24th transistor T24 is lower than 0.7V, the collector and emitter of the 24th transistor T24 are turned off, and the 24th transistor T24 is turned off.

[0029] Specifically, the control unit 11 further includes an eleventh grounding capacitor C11, which is electrically connected to the series connection point of the eighth resistor R8 and the ninth resistor R9. One end of the eleventh grounding capacitor C11 is grounded, and the other end is electrically connected to the series connection point of the eighth resistor R8 and the ninth resistor R9. The eleventh grounding capacitor C11 can provide soft start and filtering for the control unit 11.

[0030] Preferably, the overvoltage protection circuit 10 further includes a fifteenth capacitor C15, one end of which is electrically connected to the series node of the sixth resistor R6 and the twelfth resistor R12, and the other end of which is connected to the power supply module, so that the fifteenth capacitor C15 is connected in parallel with the sixth resistor R6, serving as a soft start and filter.

[0031] Specifically, the overvoltage protection circuit also includes a fuse RB1 and a tenth diode D10. The power supply module is connected to the eighth switching transistor T8 via the fuse RB1 and the tenth diode D10. The fuse RB1 can be a 2A fuse. The power supply module is connected to one end of the fuse RB1, and the other end of the fuse RB1 is connected to the anode of the tenth diode D10. The cathode of the tenth diode D10 is connected to the eighth switching transistor T8. By setting the fuse RB1, short-circuit protection can be provided. The tenth diode D10 can be an SS26 diode with a reverse withstand voltage of 60V for reverse connection protection.

[0032] Specifically, the overvoltage protection circuit 10 further includes a second grounding capacitor C2, which is connected to the power supply module. One end of the second grounding capacitor C2 is grounded, and the other end is connected to the power supply module and one end of the fuse RB1. The second grounding capacitor C2 is used for filtering.

[0033] Based on the above design, during operation, when the received power supply voltage from the power supply module is lower than the protection voltage threshold, the series-connected fifth and tenth resistors, together with the third diode, work together to reduce the voltage difference between the emitter and base of the second transistor to below 0.7V, thus turning off the voltage between the emitter and collector of the second transistor. The eighth and ninth resistors in the control unit then divide the power supply voltage output from the power supply module and transmit it to the base of the twenty-fourth transistor, making the voltage difference between the base and emitter of the twenty-fourth transistor greater than 0.7V. This results in the voltage difference between the collector and emitter of the twenty-fourth transistor being reduced. When the collector of the 24th transistor is turned on, the collector of the 24th transistor can be connected to ground. This means the power supply voltage output from the power supply module can be transmitted to the gates of the 8th and 3rd switching transistors after being divided and current-limited by the 6th and 12th resistors connected in series. This ensures that the voltage difference between the gate and source of the 8th switching transistor is less than -2.6V, and the voltage difference between the gate and source of the 3rd switching transistor is also less than -2.6V. Therefore, the source and drain of the 8th switching transistor are connected, and the source and drain of the 3rd switching transistor are also connected. In other words, both the 8th and 3rd switching transistors are turned on, and the power supply module normally supplies power to the level conversion circuit and feeds the power back to the 8th switching transistor. The base of the diode / transistor ensures that the protection voltage threshold is higher than the recovery voltage threshold, achieving a hysteresis effect. When the received power supply voltage from the power supply module is not lower than the protection voltage threshold, the series-connected fifth and tenth resistors, together with the third diode, work together to make the voltage difference between the emitter and base of the second diode greater than 0.7V, causing the emitter and collector of the second diode to conduct. The second diode is then turned on, the sixth resistor is short-circuited, and the gates of both the eighth and third switching transistors are pulled up to the supply voltage. This results in a voltage difference between the gate and source of the eighth switching transistor greater than -2.6V, and the gate of the third switching transistor... If the voltage difference between the source and the source is greater than -2.6V, the source and drain of the eighth switch are turned off, and the source and drain of the third switch are also turned off. That is, both the eighth and third switches are turned off, disconnecting the power supply module from the level conversion circuit and protecting the level conversion circuit. At the same time, the power supply voltage feedback to the base of the second transistor is disconnected, so that the recovery voltage threshold is lower than the protection voltage threshold, achieving a hysteresis effect. When the received power supply voltage from the power supply module drops to the recovery voltage threshold, it automatically switches to the working process when the received power supply voltage from the power supply module is lower than the protection voltage threshold, realizing the self-recovery function.

[0034] In summary, the overvoltage protection circuit of this utility model is electrically connected between the power supply module and the level conversion circuit. When the supply voltage of the power supply module exceeds a preset protection voltage threshold, it disconnects the power supply from the power supply module to the level conversion circuit, thus protecting the level conversion circuit. The overvoltage protection circuit uses a third diode, a second transistor, and a series-connected fifth and tenth resistors to achieve current limiting and voltage division when the third diode and the second transistor are conducting, collectively forming a protection voltage threshold setting and protection circuit. It also includes a third switch connected to the power supply module, a first resistor connected to the third switch and the tenth resistor respectively, an eighth switch electrically connected between the power supply module and the level conversion circuit, a series-connected sixth and twelfth resistors, and a control unit connected to the twelfth resistor. The power supply module is connected to the sixth resistor and the control unit, thus enabling the power supply module, the second... A loop is formed between the sixth resistor, the twelfth resistor, and the control unit. The control terminals of the third and eighth switching transistors are electrically connected to the series node of the sixth and twelfth resistors. The control unit controls the on / off state of the third and eighth switching transistors to control the power supply from the power supply module to the level conversion circuit. The first resistor is connected to the power supply module through the third switching transistor and electrically connected to the series node of the fifth and tenth resistors, so as to be connected to the base of the second transistor. The base of the second transistor is electrically connected to the series node of the fifth and tenth resistors to realize feedback control of the second transistor based on the on / off state of the eighth switching transistor. This results in a difference between the protection voltage threshold and the recovery voltage threshold, realizing the hysteresis function. The protection voltage threshold is higher than the recovery voltage threshold to prevent the protection from failing due to repeated on / off switching when the power supply voltage is unstable.

[0035] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. An overvoltage protection circuit, characterized in that, The overvoltage protection circuit is electrically connected between the power supply module and the level conversion circuit. The overvoltage protection circuit includes a third diode, a second transistor, a third switching transistor, an eighth switching transistor, a first resistor, a fifth resistor, a sixth resistor, a tenth resistor, a twelfth resistor, and a control unit. The control unit controls the operation of the eighth and third switching transistors. The fifth and tenth resistors are connected in series. The power supply module is connected to the series node of the fifth and tenth resistors via the third switching transistor and the first resistor. The base of the second transistor is electrically connected to the series node of the fifth and tenth resistors. The power supply module and the... The emitter of the second transistor is connected, the sixth resistor is connected in series with the twelfth resistor, the power supply module is connected to the sixth resistor, the power supply module is connected to the twelfth resistor through the control unit, the power supply module is connected to the level conversion circuit through the eighth switch, the control terminal of the eighth switch, the collector of the second transistor, and the control terminal of the third switch are all electrically connected to the series node of the sixth and twelfth resistors, so that the second transistor is connected in parallel with the sixth resistor, the power supply module is connected to the cathode of the third diode through the fifth and tenth resistors, and the anode of the third diode is grounded.

2. The overvoltage protection circuit according to claim 1, characterized in that, The eighth switch is a PMOS transistor. The source of the eighth switch is connected to the power supply module, the drain of the eighth switch is connected to the level conversion circuit, and the gate of the eighth switch is electrically connected to the series node of the sixth resistor and the twelfth resistor.

3. The overvoltage protection circuit according to claim 1, characterized in that, The third switch is a PMOS transistor. The source of the third switch is connected to the power supply module, the drain of the third switch is connected to the first end of the first resistor, the second end of the first resistor is electrically connected to the series node of the fifth resistor and the tenth resistor, and the gate of the third switch is electrically connected to the series node of the sixth resistor and the twelfth resistor.

4. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes a fourteenth diode, the anode of which is connected to the series node of the sixth resistor and the twelfth resistor, and the cathode of which is connected to the power supply module so that the fourteenth diode is connected in parallel with the sixth resistor.

5. The overvoltage protection circuit according to claim 4, characterized in that, Both the third and fourteenth diodes are Zener diodes.

6. The overvoltage protection circuit according to claim 1, characterized in that, The control unit includes an eighth resistor, a ninth resistor, and a twenty-fourth transistor. The eighth resistor is connected in series with the ninth resistor. The power supply module is connected to the eighth resistor. The ninth resistor is grounded. The base of the twenty-fourth transistor is electrically connected to the series node of the eighth and ninth resistors. The collector of the twenty-fourth transistor is connected to the twelfth resistor. The emitter of the twenty-fourth transistor is grounded.

7. The overvoltage protection circuit according to claim 6, characterized in that, The 24th transistor is an NPN transistor, and the 2nd transistor is a PNP transistor.

8. The overvoltage protection circuit according to claim 6, characterized in that, The control unit also includes an eleventh grounding capacitor, which is electrically connected to the series node of the eighth resistor and the ninth resistor.

9. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes a fuse and a tenth diode, and the power supply module is connected to the eighth switching transistor via the fuse and the tenth diode.

10. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit further includes a second grounding capacitor and a fifteenth capacitor. The second grounding capacitor is connected to the power supply module. One end of the fifteenth capacitor is electrically connected to the series node of the sixth resistor and the twelfth resistor, and the other end of the fifteenth capacitor is connected to the power supply module.

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