CN218549490U - Linear overvoltage protection circuit and electronic equipment - Google Patents

Abstract

The utility model discloses a linear overvoltage crowbar and electronic equipment, wherein the linear overvoltage crowbar comprises a power input end, a power output end, a first switch circuit and a switch control circuit; the first switch circuit is arranged between the power input end and the power output end in series, the controlled end of the switch control circuit is connected with the power output end, and the control end of the switch control circuit is connected with the first switch circuit. The utility model discloses a switch control circuit detects power output end's output voltage to when detecting power output end's output voltage excessive pressure, control first switch circuit and turn-off, with the electricity between disconnect-supply input end and the power output end to be connected, damage in order to avoid electronic equipment excessive pressure, thereby improve electronic equipment's security.

Description

Linear overvoltage protection circuit and electronic equipment

technical field

The utility model relates to the technical field of overvoltage protection, in particular to a linear overvoltage protection circuit and electronic equipment.

Background technique

For most electronic equipment, the basic condition to ensure safe and reliable operation is a stable input power supply voltage.

In actual situations, the external power supply may not be compatible, such as the external power supply voltage is unstable or has high-energy pulses. If the electronic device is connected to the external power supply, it may cause subsequent important problems in the electronic device. Abnormal conditions such as overvoltage occur in circuits and electronic components, or even be damaged.

Utility model content

The main purpose of the utility model is to provide a linear overvoltage protection circuit, aiming at solving the problem that the external power supply with high-energy pulse easily causes damage to electronic equipment.

In order to achieve the above purpose, the utility model proposes a linear overvoltage protection circuit, the linear overvoltage protection circuit includes:

Power input and power output;

A first switch circuit, the first switch circuit is arranged in series between the power supply input terminal and the power supply output terminal, and the first switch circuit is used to control the power supply input terminal and the power supply output terminal when turned on Terminal connection;

A switch control circuit, the controlled terminal of the switch control circuit is connected to the output terminal of the power supply, the control terminal of the switch control circuit is connected to the first switch circuit, and the switch control circuit is used to detect the output of the power supply The output voltage of the terminal, and when the output voltage of the output terminal of the power supply is detected to be overvoltage, control the first switch circuit to turn off, so as to disconnect the electrical connection between the input terminal of the power supply and the output terminal of the power supply.

In an embodiment, the switch control circuit is further configured to detect the output voltage of the power output terminal after controlling the first switch circuit to disconnect the electrical connection between the power supply input terminal and the power supply output terminal. When returning to normal, the first switch circuit is controlled to be turned on, so as to control the power supply input terminal and the power supply output terminal to restore electrical connection.

In one embodiment, the switch control circuit includes a switch maintenance circuit and an overvoltage shutdown circuit; the switch maintenance circuit is arranged in series between the power supply input terminal and the first switch circuit, and the overvoltage shutdown circuit The input terminal of the breaking circuit is connected to the input terminal of the power supply, the controlled terminal of the overvoltage shutdown circuit is connected to the output terminal of the power supply, and the output terminal of the overvoltage shutdown circuit is grounded.

In one embodiment, the switch maintaining circuit includes a first resistor and a second resistor, one end of the first resistor is connected to the power supply input end, the other end of the first resistor is connected to the second resistor The other end of the first resistor is also connected to the controlled end of the first switch circuit, and the other end of the second resistor is grounded.

In one embodiment, the overvoltage shutdown circuit includes a third resistor, a fourth resistor, a first switch tube, and a second switch tube, and the controlled end of the first switch tube communicates with the third resistor through the third resistor. The output end of the power supply is connected, the controlled end of the second switching tube is connected to the input end of the first switching tube through the fourth resistor, and the input end of the second switching tube is connected to the input end of the power supply.

In one embodiment, the first switch transistor is an NPN transistor, and the second switch transistor is a PNP transistor.

In one embodiment, the linear overvoltage protection circuit further includes a reference voltage circuit, the input terminal of the reference voltage circuit is connected to the output terminal of the power supply, and the output terminal of the reference voltage circuit is connected to the overvoltage shutdown The controlled end of the circuit is connected, and the reference voltage circuit is used to trigger the overvoltage shutdown circuit when the output voltage of the output terminal of the power supply exceeds the reference voltage value.

In one embodiment, the reference voltage circuit is a Zener diode.

In one embodiment, the linear overvoltage protection circuit further includes a voltage stabilizing circuit, the voltage stabilizing circuit is arranged in series between the switch maintaining circuit and the first switching circuit, and the voltage stabilizing circuit is used for The input voltage at the input terminal of the power supply is output after being regulated.

The utility model also proposes an electronic device, which includes the above-mentioned linear overvoltage protection circuit.

The technical scheme of the utility model detects the output voltage of the power supply output terminal through the switch control circuit, and when the output voltage of the power supply output terminal is detected to be overvoltage, controls the first switch circuit to turn off, so as to disconnect the power supply input terminal and the power supply output terminal. Electrical connection, that is, to stop the high-voltage power supply to the electronic equipment, to avoid the electronic equipment from being burned out due to overvoltage, thereby improving the safety of the electronic equipment.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the present utility model, and those skilled in the art can also obtain other drawings according to the structures shown in these drawings without creative work.

Fig. 1 is the overall block diagram of an embodiment of the linear overvoltage protection circuit of the present invention;

Fig. 2 is the circuit diagram of another embodiment of the utility model linear overvoltage protection circuit;

FIG. 3 is a circuit diagram of another embodiment of the linear overvoltage protection circuit of the present invention.

Explanation of reference numbers:

label name label name 10 first switch circuit Q1 first switching tube 20 switch control circuit Q2 second switch tube 30 Reference voltage circuit Q3 PMOS tube 40 Regulator circuit R1～R4 1st to 4th resistors twenty one Overvoltage Shutdown Circuit R5 Current limiting resistor twenty two switch hold circuit Z1 Zener diode Vin power input Vout Power output

The realization of the purpose of the utility model, functional characteristics and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

In addition, in the present application, descriptions such as "first", "second" and so on are used for description purposes only, and should not be understood as indicating or implying their relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In addition, the technical solutions of the various embodiments can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist , also not within the scope of protection required by the utility model.

The utility model provides a linear overvoltage protection circuit.

At present, the external power supply connected to electronic equipment has unstable voltage or high-energy pulses, which may cause abnormal conditions such as overvoltage and even damage to subsequent important circuits and electronic components in electronic equipment.

In order to solve the above problems, referring to Fig. 1 to Fig. 3, in an embodiment of the present invention, the linear overvoltage protection circuit is applied to electronic equipment, and the high energy pulse can be eliminated through the linear overvoltage protection circuit, providing electronic equipment with Appropriate working voltage to prevent electronic equipment from being damaged due to overvoltage. The linear overvoltage protection circuit includes: a power supply input terminal Vin and a power supply output terminal Vout; a first switch circuit 10, and the first switch circuit 10 is arranged in series between the power supply input terminal Vin and the power supply output terminal Vout , the first switch circuit 10 is used to control the electrical connection between the power supply input terminal Vin and the power supply output terminal Vout when it is turned on; the switch control circuit 20, the controlled terminal of the switch control circuit 20 is connected to the power output terminal terminal Vout, the control terminal of the switch control circuit 20 is connected to the first switch circuit 10, the switch control circuit 20 is used to detect the output voltage of the output terminal Vout of the power supply, and detect the output voltage of the power supply output When the output voltage of the terminal Vout is overvoltage, the first switch circuit 10 is controlled to be turned off, so as to disconnect the electrical connection between the power input terminal Vin and the power output terminal Vout.

Wherein, the first switch circuit 10 can be implemented by using a high-voltage PMOS transistor Q3. When the voltage of the PMOS transistor Q3GS pole is greater than the turn-on voltage of the PMOS transistor Q3GS pole, it will be turned on. The specific withstand voltage value of the PMOS transistor Q3 can be determined according to the power input terminal. Vin input voltage range selection. Specifically, when the input voltage of the power input terminal Vin is greater than the turn-on voltage of the PMOS transistor Q3GS, the PMOS transistor Q3 is turned on, even if the power input terminal Vin is connected to the power output terminal Vout; when the input voltage of the power input terminal Vin is less than When the turn-on voltage of the PMOS transistor Q3GS is high, the PMOS transistor Q3 is disconnected, that is, the circuit between the power input terminal Vin and the power output terminal Vout is disconnected, thereby controlling the on-off between the power input terminal Vin and the power output terminal Vout.

The switch control circuit 20 can adopt any switch control circuit 20 that can control the first switch circuit 10 to turn off when the output voltage of the output terminal Vout of the power supply is detected to be overvoltage. Specifically, the switch control circuit 20 may include a switch maintaining circuit 22 and an overvoltage shutdown circuit 21. The overvoltage shutdown circuit 21 is turned on when the output voltage of the output terminal Vout of the power supply is detected to be overvoltage, that is, the switch maintaining circuit is turned off. 22 is connected to the power input terminal Vin, so as to control the first switch circuit 10 to turn off, so as to disconnect the electrical connection between the power input terminal Vin and the power output terminal Vout; thereafter, the overvoltage shutdown circuit 21 detects that the power When the output voltage of the output terminal Vout returns to normal, it is disconnected, that is, the switch is turned on to maintain the connection between the circuit 22 and the power supply input terminal Vin, thereby controlling the conduction of the first switch circuit 10, so as to connect the power supply input terminal Vin and the power supply output terminal Vout. The electrical connection realizes the on-off control of the first switch circuit 10 through the switch maintenance circuit 22 and the overvoltage shutdown circuit 21 .

The technical scheme of the utility model detects the output voltage of the power supply output terminal Vout through the switch control circuit 20, and when the output voltage of the power supply output terminal Vout is detected to be overvoltage, controls the first switch circuit 10 to turn off, so as to disconnect the power supply input terminal Vin and the electrical connection between the power output terminal Vout, that is, stop supplying high-voltage power to the electronic equipment, so as to prevent the electronic equipment from being burned out due to overvoltage, thereby improving the safety of the electronic equipment.

1 to 3, in an embodiment, the switch control circuit 20 is also used to control the first switch circuit 10 to disconnect the electrical connection between the power input terminal Vin and the power output terminal Vout When detecting that the output voltage of the power supply output terminal Vout returns to normal, control the first switch circuit 10 to be turned on, so as to control the power supply input terminal Vin and the power supply output terminal Vout to restore electrical connection.

In this embodiment, after the switch control circuit 20 controls the first switch circuit 10 to turn off when the output voltage of the power supply output terminal Vout is overvoltage, the output voltage of the power supply output terminal Vout begins to drop. When the switch control circuit 20 detects that the power output When the output voltage of the terminal Vout returns to normal, the first switch circuit 10 is controlled to be turned on, so that the power supply input terminal Vin and the power supply output terminal Vout are electrically connected, and the cycle is repeated to output a linear straight-line voltage, which can effectively convert the high-amplitude High-energy pulses with high value and long time are eliminated to realize overvoltage protection, which can prevent electronic equipment from being damaged in high-voltage workplaces.

2 and 3, in one embodiment, the switch control circuit 20 includes a switch maintenance circuit 22 and an overvoltage shutdown circuit 21; the switch maintenance circuit 22 is arranged in series between the power supply input terminal Vin and the Between the first switch circuits 10, the input terminal of the overvoltage shutdown circuit 21 is connected to the power supply input terminal Vin, and the controlled terminal of the overvoltage shutdown circuit 21 is connected to the power supply output terminal Vout, so The output end of the overvoltage shutdown circuit 21 is grounded.

Wherein, the switch maintaining circuit 22 can be realized by a voltage divider circuit, which divides the input voltage of the power supply input terminal Vin and then outputs it to the first switch circuit 10 . Specifically, the switch maintenance circuit 22 includes a first resistor R1 and a second resistor R2, one end of the first resistor R1 is connected to the power input terminal Vin, and the other end of the first resistor R1 is connected to the second resistor R1. One end of the resistor R2 is connected, the other end of the first resistor R1 is also connected to the controlled end of the first switch circuit 10 , and the other end of the second resistor R2 is grounded. In this embodiment, when the voltage of the first resistor R1 is greater than the turn-on voltage of the PMOS transistor Q3GS, the PMOS transistor Q3 is turned on, that is, the power input terminal Vin is connected to the power supply output terminal Vout; on the contrary, when the first resistor R1 When the voltage is lower than the turn-on voltage of the PMOS transistor Q3GS, the PMOS transistor Q3 is disconnected, that is, the loop between the power input terminal Vin and the power output terminal Vout is disconnected, thereby controlling the on-off of the PMOS transistor Q3.

The overvoltage shutdown circuit 21 can be realized by using a switch circuit. Specifically, the overvoltage shutdown circuit 21 includes a third resistor R3, a fourth resistor R4, a first switch tube Q1, and a second switch tube Q2, and the controlled end of the first switch tube Q1 passes through the third resistor R3 is connected to the output terminal Vout of the power supply, the controlled terminal of the second switching tube Q2 is connected to the input terminal of the first switching tube Q1 through the fourth resistor R4, and the input terminal of the second switching tube Q2 is connected to the input terminal of the first switching tube Q2. The power input terminal Vin is connected. It should be noted that the first switching transistor Q1 is an NPN transistor, and the second switching transistor Q2 is a PNP transistor. When the power supply output terminal Vout is overvoltage, the NPN transistor can be turned on, so that the PNP transistor is turned on, that is, the switch maintains the connection between the circuit 22 and the power input terminal Vin, thereby controlling the first switch circuit 10 to turn off, To disconnect the electrical connection between the power input terminal Vin and the power output terminal Vout; when the output voltage of the power output terminal Vout returns to normal, the NPN transistor can be turned off, so that the PNP transistor is turned off, even if the switch maintains the circuit 22 is connected to the power input terminal Vin, so as to control the conduction of the first switch circuit 10, so as to make the electrical connection between the power input terminal Vin and the power output terminal Vout, and realize the control of the power supply input terminal Vin and the power supply output terminal Vout through the overvoltage shutdown circuit 21. On-off between the power supply output terminals Vout.

In this embodiment, the overvoltage shutdown circuit 21 is turned on when it detects that the output voltage of the output terminal Vout of the power supply is overvoltage, that is, the connection between the switch maintenance circuit 22 and the input terminal Vin of the power supply is disconnected, thereby controlling the first switch circuit 10 Turn off to disconnect the electrical connection between the power supply input terminal Vin and the power supply output terminal Vout; thereafter, when the overvoltage shutdown circuit 21 detects that the output voltage of the power supply output terminal Vout returns to normal, it is disconnected, that is, the switch is turned on Maintaining the connection between the circuit 22 and the power input terminal Vin, so as to control the conduction of the first switch circuit 10, so as to conduct the electrical connection between the power input terminal Vin and the power output terminal Vout, and realize the maintenance circuit 22 and the overvoltage shutdown circuit 21 through the switch Controlling the on-off of the first switch circuit 10 .

2 and 3, in one embodiment, the linear overvoltage protection circuit further includes a reference voltage circuit 30, the input terminal of the reference voltage circuit 30 is connected to the output terminal Vout of the power supply, and the reference voltage circuit The output end of 30 is connected to the controlled end of the overvoltage shutdown circuit 21, and the reference voltage circuit 30 is used to trigger the overvoltage shutdown when the output voltage of the output terminal Vout of the power supply exceeds the reference voltage value. Circuit 21.

Wherein, the reference voltage circuit 30 can be realized by using a Zener diode Z1 or a three-terminal voltage regulator. In this embodiment, the reference voltage circuit 30 is realized by using the Zener diode Z1, which is simpler and lower in cost than a three-terminal voltage regulator. It is worth noting that a current-limiting resistor R5 is set at the output end of the Zener diode Z1 to protect the Zener diode Z1 from burning out due to overvoltage.

In this embodiment, when the input voltage of the power supply input terminal Vin is lower than the reference voltage value, since the output voltage of the power supply output terminal Vout is always lower than the reference voltage value, the overvoltage shutdown circuit 21 is always in the off state, that is, the first A switch circuit 10 is still in a fully conducting state, and finally the output voltage of the power supply output terminal Vout is equal to the input voltage of the power supply input terminal Vin; when the input voltage of the power supply input terminal Vin is greater than the reference voltage value, due to the The output voltage is greater than the reference voltage value, the overvoltage shutdown circuit 21 is in the conduction state, thereby disconnecting the connection between the switch maintenance circuit 22 and the power input terminal Vin, that is, controlling the first switch circuit 10 to turn off, so as to disconnect the power input terminal The electrical connection between Vin and the power supply output terminal Vout, thereafter, the output voltage of the power supply output terminal Vout begins to drop until the output voltage of the power supply output terminal Vout is lower than the reference voltage value, the overvoltage shutdown circuit 21 is in a disconnected state, That is, the first switch circuit 10 is turned on to conduct the electrical connection between the power supply input terminal Vin and the power supply output terminal Vout, and the high-amplitude and long-time high-energy pulses are effectively eliminated through the reference voltage circuit 30 to realize overvoltage protection, and the The output voltage of the output terminal Vout of the power supply is maintained within the range of the reference voltage, which provides a nearly linear straight-line voltage for the electronic equipment to avoid electromagnetic interference.

Referring to FIG. 2 and FIG. 3 , in one embodiment, the linear overvoltage protection circuit further includes a voltage stabilizing circuit 40, and the voltage stabilizing circuit 40 is arranged in series between the switch maintenance circuit 22 and the first switch circuit 10 , the voltage stabilizing circuit 40 is used to stabilize the input voltage of the power supply input terminal Vin and then output it.

Wherein, the voltage stabilizing circuit 40 can be realized by any voltage stabilizing circuit 40 capable of stabilizing the input power, for example, a voltage stabilizing diode.

In this embodiment, the voltage stabilizing circuit 40 is arranged between the switch maintaining circuit 22 and the first switching circuit 10, and outputs the input voltage after a voltage stabilizing process to protect the first switching circuit 10, that is, protect the GS of the PMOS transistor Q3. Pole, to avoid PMOS tube Q3 overvoltage and burn out.

In combination with the above-mentioned embodiments, the inventive concept of the present utility model is described. In the first case, the input voltage of the power supply input terminal Vin is less than the voltage regulation value of the Zener diode Z1. The first switch tube Q1 is in the cut-off state, the second switch tube Q2 is also in the cut-off state, the first resistor R1 and the second resistor R2 form a voltage divider circuit, and the voltage divided by the first resistor R1 is greater than the turn-on voltage of the PMOS transistor Q3GS, so that the PMOS The transistor Q3 is turned on, so that the output voltage of the output terminal Vout of the power supply starts to rise. Because the input voltage Vin is less than the regulated voltage value of the Zener diode Z1, the first switching tube Q1 and the second switching tube Q2 are still working in the cut-off state, and the PMOS transistor Q3 is still working in the fully conducting state, and finally the working voltage of the electronic device is It is equal to the input voltage of the power supply input terminal Vin.

Situation 2: The working condition of the circuit in which the input voltage of the power supply input terminal Vin is greater than the regulated voltage value of the Zener diode Z1: when the power is first turned on, the Vr voltage is 0V, the first switching tube Q1 is in the cut-off state, and the second switching tube Q2 is also in the cut-off state. In the cut-off state, the first resistor R1 and the second resistor R2 form a voltage divider circuit, and the voltage divided by the first resistor R1 is greater than the turn-on voltage of the PMOS transistor Q3GS, so that the PMOS transistor Q3 is turned on, so that the output voltage of the power supply output terminal Vout Start to rise; when the output voltage of the power supply output terminal Vout is greater than the regulated value of the Zener diode Z1, and the Vr voltage is greater than 0.7V, the first switch Q1 is in the conduction state, and the second switch Q2 is also in the conduction state state, because the second switching transistor Q2 is turned on, the voltage of the first resistor R1 is 0V, that is, the voltage of the GS pole of the PMOS transistor Q3 is lower than the turn-on voltage of the PMOS transistor Q3, and the PMOS transistor Q3 is turned off. When the PMOS transistor Q3 is disconnected, the output voltage of the power supply output terminal Vout begins to drop, and the Vr voltage also drops. When the Vr voltage is less than 0.7V, the first switching tube Q1 is in the off state, and the second switching tube Q2 is also in the off state. , the voltage divided by the first resistor R1 is greater than the turn-on voltage of the PMOS transistor Q3GS, so that the PMOS transistor Q3 is turned on again, and the output voltage of the power supply output terminal Vout starts to rise, and the cycle repeats, so that the output voltage of the power supply output terminal Vout has been kept at a stable voltage The diode Z1 is close to the stable voltage range, so that the electronic equipment can work at a stable voltage.

It should be noted that the Vr voltage is the voltage at the positive terminal of the Zener diode Z1. After the PMOS transistor Q3 is disconnected, when the output voltage of the power supply output terminal Vout is lower than the voltage regulation value of the Zener diode Z1, the PMOS transistor Q3 will be turned on again, so the output voltage of the power supply output terminal Vout has been kept at the voltage regulation value of the Zener diode Z1. In the vicinity of the stable voltage value range, the output voltage of the power supply output terminal Vout is not a square wave but a linear voltage close to linear to avoid electromagnetic interference.

In summary, the linear overvoltage protection circuit can effectively eliminate high-amplitude, long-time high-energy pulses, thereby performing overvoltage protection on electronic equipment.

The utility model also proposes an electronic device, which includes the above-mentioned linear overvoltage protection circuit; the specific structure of the linear overvoltage protection circuit refers to the above-mentioned embodiments, because this electronic device adopts all the technical solutions of all the above-mentioned embodiments , so at least it has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

Wherein, the electronic equipment is connected with the power supply output terminal Vout of the linear overvoltage protection circuit. In this embodiment, the linear overvoltage protection circuit detects the output voltage of the power supply output terminal Vout to control the on-off of the first switch circuit 10, and the high-amplitude , High-energy pulses with a long time are eliminated, so that the output voltage is kept within the reference voltage range, and a stable working voltage is provided for the electronic equipment, thereby improving the safety of the electronic equipment.

The above is only an optional embodiment of the utility model, and does not therefore limit the patent scope of the utility model. Under the inventive concept of the utility model, the equivalent structural transformation made by using the specification of the utility model and the contents of the accompanying drawings, Or directly/indirectly used in other related technical fields are all included in the patent protection scope of the present utility model.

Claims (10)

1. A linear overvoltage protection circuit, characterized in that, the linear overvoltage protection circuit comprises: Power input and power output; A first switch circuit, the first switch circuit is arranged in series between the power supply input terminal and the power supply output terminal, and the first switch circuit is used to control the power supply input terminal and the power supply output terminal when turned on Terminal connection; A switch control circuit, the controlled terminal of the switch control circuit is connected to the output terminal of the power supply, the control terminal of the switch control circuit is connected to the first switch circuit, and the switch control circuit is used to detect the output of the power supply The output voltage of the terminal, and when the output voltage of the output terminal of the power supply is detected to be overvoltage, control the first switch circuit to turn off, so as to disconnect the electrical connection between the input terminal of the power supply and the output terminal of the power supply. 2. The linear overvoltage protection circuit according to claim 1, wherein the switch control circuit is also used to control the first switch circuit to disconnect the power supply between the power supply input terminal and the power supply output terminal. After the connection, when it is detected that the output voltage of the output terminal of the power supply returns to normal, the first switch circuit is controlled to be turned on, so as to control the input terminal of the power supply and the output terminal of the power supply to restore electrical connection. 3. The linear overvoltage protection circuit according to claim 1, wherein the switch control circuit comprises a switch maintenance circuit and an overvoltage shutdown circuit; the switch maintenance circuit is arranged in series with the input terminal of the power supply and the between the first switching circuits, the input terminal of the overvoltage shutdown circuit is connected to the input terminal of the power supply, the controlled terminal of the overvoltage shutdown circuit is connected to the output terminal of the power supply, and the overvoltage shutdown circuit The output of the break circuit is grounded. 4. The linear overvoltage protection circuit according to claim 3, wherein the switch maintenance circuit comprises a first resistor and a second resistor, one end of the first resistor is connected to the power input terminal, and the The other end of the first resistor is connected to one end of the second resistor, the other end of the first resistor is also connected to the controlled end of the first switch circuit, and the other end of the second resistor is grounded. 5. The linear overvoltage protection circuit according to claim 3, wherein the overvoltage shutdown circuit comprises a third resistor, a fourth resistor, a first switch tube and a second switch tube, and the first switch The controlled end of the tube is connected to the output end of the power supply through the third resistor, the controlled end of the second switch tube is connected to the input end of the first switch tube through the fourth resistor, and the second switch tube is connected to the input end of the first switch tube through the fourth resistor. The input end of the tube is connected with the power input end. 6. The linear overvoltage protection circuit according to claim 5, wherein the first switch transistor is an NPN transistor, and the second switch transistor is a PNP transistor. 7. The linear overvoltage protection circuit according to claim 3, wherein the linear overvoltage protection circuit further comprises a reference voltage circuit, the input end of the reference voltage circuit is connected to the output end of the power supply, and the The output terminal of the reference voltage circuit is connected to the controlled terminal of the overvoltage shutdown circuit, and the reference voltage circuit is used to trigger the overvoltage shutdown circuit when the output voltage of the output terminal of the power supply exceeds a reference voltage value. 8. The linear overvoltage protection circuit according to claim 7, wherein the reference voltage circuit is a Zener diode. 9. The linear overvoltage protection circuit according to claim 7, wherein the linear overvoltage protection circuit further comprises a voltage stabilizing circuit, and the voltage stabilizing circuit is arranged in series with the switch maintenance circuit and the first switch circuit Between, the voltage stabilizing circuit is used to stabilize the input voltage of the power supply input terminal and then output it. 10. An electronic device, characterized in that the electronic device comprises the linear overvoltage protection circuit according to any one of claims 1-9.

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