CN215990187U - Overvoltage protection circuit, overvoltage protection system and electronic equipment - Google Patents

Abstract

The disclosure provides an overvoltage protection circuit, an overvoltage protection system and an electronic device. The circuit includes: the circuit comprises a first switch, a second switch, a third switch, a first pull-up resistor, a second pull-up resistor and a time delay unit; the control end of the first switch is electrically connected with the input end of a power line, the first end of the first switch is electrically connected with the first end of the first pull-up resistor, the first end of the delay unit and the control end of the second switch, the first end of the second switch is electrically connected with the first end of the second pull-up resistor and the control end of the third switch respectively, the second end of the first pull-up resistor, the second end of the second pull-up resistor and the first end of the third switch are electrically connected with the input end of the power line, the second ends of the first switch, the second switch and the delay unit are grounded, and the second end of the third switch is electrically connected with the output end of the power line; and the delay unit is used for delaying the conduction of the second switch when the received initial input voltage is greater than the protection voltage. The circuit can reduce the cost of the overvoltage protection circuit.

Description

Overvoltage protection circuit, overvoltage protection system and electronic equipment

Technical Field

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

Background

In the case of increasingly stringent cost control of low-end terminal equipment, it is desirable to minimize the cost of the components within the terminal equipment, and therefore, even eliminate the overvoltage protection chip for a period of time. However, these low-end terminals need to be exported to countries such as africa, and these countries have unstable voltage and are liable to cause load breakdown, so that it is still necessary to provide an overvoltage protection circuit in the terminal.

In the prior art, a plurality of capacitors and transient diodes are needed in the overvoltage protection circuit, which results in higher cost of the overvoltage protection circuit and is not beneficial to reducing the cost of the terminal equipment.

SUMMERY OF THE UTILITY MODEL

The present disclosure provides an overvoltage protection circuit, an overvoltage protection system, and an electronic apparatus, which can reduce the cost of the overvoltage protection circuit.

In a first aspect, the present disclosure provides an overvoltage protection circuit, comprising: the circuit comprises a first switch, a second switch, a third switch, a first pull-up resistor, a second pull-up resistor and a time delay unit;

the control end of the first switch is electrically connected with the input end of a power line, the first end of the first switch is respectively electrically connected with the first end of the first pull-up resistor, the first end of the delay unit and the control end of the second switch, the first end of the second switch is respectively electrically connected with the first end of the second pull-up resistor and the control end of the third switch, the second end of the first pull-up resistor, the second end of the second pull-up resistor and the first end of the third switch are electrically connected with the input end of the power line, the second end of the first switch, the second end of the second switch and the second end of the delay unit are all grounded, and the second end of the third switch is electrically connected with the output end of the power line;

and the time delay unit is used for delaying the conduction of the second switch when the initial input voltage received by the input end of the power line is greater than the protection voltage so as to conduct the first switch before conducting the second switch.

Optionally, the overvoltage protection circuit further includes: a voltage regulating unit;

the first end of the voltage regulating unit is electrically connected with the input end of the power line, the second end of the voltage regulating unit is electrically connected with the control end of the first switch, and the third end of the voltage regulating unit is grounded;

and the voltage regulating unit is used for regulating the protection voltage of the overvoltage protection circuit.

Optionally, the delay unit includes: a capacitor;

the first end of the capacitor is respectively electrically connected with the first end of the first switch and the control end of the second switch, and the second end of the capacitor is grounded.

Optionally, the voltage regulating unit includes: the circuit comprises a first resistor, a second resistor, a third resistor and a fourth resistor;

the first end of the first resistor is electrically connected with the input end of the power line, the second end of the first resistor is respectively electrically connected with the first end of the second resistor, the first end of the third resistor and the first end of the fourth resistor, the second end of the second resistor and the second end of the third resistor are both grounded, and the second end of the fourth resistor is electrically connected with the control end of the first switch.

Optionally, the first switch includes a first triode, a base of the first triode is electrically connected to a control terminal of the first switch, a collector of the first triode is electrically connected to a first terminal of the first switch, and an emitter of the first triode is electrically connected to a second terminal of the first switch;

the second switch comprises a second triode, the base electrode of the second triode is electrically connected with the control end of the second switch, the collector electrode of the second triode is electrically connected with the first end of the second switch, and the emitter electrode of the second triode is electrically connected with the second end of the second switch.

Optionally, the overvoltage protection circuit further comprises: a first pull-down resistor and a second pull-down resistor;

the first end of the first pull-down resistor is electrically connected with the base electrode of the first triode, and the second end of the first pull-down resistor is grounded;

the first end of the second pull-down resistor is electrically connected with the base electrode of the second triode, and the second end of the second pull-down resistor is grounded.

Optionally, the overvoltage protection circuit further comprises: a current limiting resistor;

the first end of the current-limiting resistor is electrically connected with the first end of the first pull-up resistor, and the second end of the current-limiting resistor is electrically connected with the base electrode of the second triode.

Optionally, the third switch includes a field effect transistor, a gate of the field effect transistor is electrically connected to a control terminal of the third switch, a drain of the field effect transistor is electrically connected to a first terminal of the third switch, and a source of the field effect transistor is electrically connected to a second terminal of the third switch.

In a second aspect, the present disclosure provides an overvoltage protection system comprising a power supply line and any one of the overvoltage protection circuits provided in the first aspect;

the overvoltage protection circuit is electrically connected between the input end and the output end of the power line.

In a third aspect, the present disclosure provides an electronic device comprising a load, a power line, and any one of the overvoltage protection circuits provided in the first aspect;

the overvoltage protection circuit is electrically connected between the input end and the output end of the power line, and the load is electrically connected with the output end of the power line.

In the technical scheme that this disclosure provided, overvoltage crowbar includes: the circuit comprises a first switch, a second switch, a third switch, a first pull-up resistor, a second pull-up resistor and a time delay unit; the control end of the first switch is electrically connected with the input end of a power line, the first end of the first switch is respectively electrically connected with the first end of the first pull-up resistor, the first end of the time delay unit and the control end of the second switch, the first end of the second switch is respectively electrically connected with the first end of the second pull-up resistor and the control end of the third switch, the second end of the first pull-up resistor, the second end of the second pull-up resistor and the first end of the third switch are electrically connected with the input end of the power line, the second end of the first switch, the second end of the second switch and the second end of the time delay unit are all grounded, the second end of the third switch is electrically connected with the output end of the power line, the time delay unit can delay the conduction of the second switch when the initial input voltage received by the input end of the power line is greater than the protection voltage, so that the first switch is conducted before the second switch is conducted, the initial input voltage signal is released to the ground after passing through the first switch, the second switch is in a cut-off state, namely the third switch is cut off, so that an initial input voltage signal cannot be output from the output end of the power line, the rear-stage load can be protected, the rear-stage load is prevented from being broken down, overvoltage protection on the rear-stage load is realized, and therefore overvoltage protection can be realized through the three switches and the delay unit, and the cost of the overvoltage protection circuit can be reduced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present disclosure, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of an overvoltage protection circuit provided by the present disclosure;

fig. 2 is a schematic structural diagram of another overvoltage protection circuit provided by the present disclosure;

fig. 3 is a schematic structural diagram of another overvoltage protection circuit provided by the present disclosure;

fig. 4 is a schematic structural diagram of another overvoltage protection circuit provided by the present disclosure;

fig. 5 is a schematic structural diagram of an overvoltage protection system provided by the present disclosure;

fig. 6 is a schematic structural diagram of an electronic device provided in the present disclosure.

Detailed Description

In order that the above objects, features and advantages of the present disclosure may be more clearly understood, aspects of the present disclosure will be further described below. It should be noted that the embodiments and features of the embodiments of the present disclosure may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure may be practiced in other ways than those described herein; it is to be understood that the embodiments disclosed in the specification are only a few embodiments of the present disclosure, and not all embodiments.

Fig. 1 is a schematic structural diagram of an overvoltage protection circuit provided in the present disclosure, and as shown in fig. 1, the overvoltage protection circuit 100 includes: the circuit comprises a first switch 110, a second switch 120, a third switch 130, a first pull-up resistor Ru1, a second pull-up resistor Ru2 and a delay unit 140.

The control terminal of the first switch 110 is electrically connected to the input terminal of the power line VBUS, the first terminal of the first switch 110 is electrically connected to the first terminal of the first pull-up resistor Ru1, the first terminal of the delay unit 140 and the control terminal of the second switch 120, the first terminal of the second switch 120 is electrically connected to the first terminal of the second pull-up resistor Ru2 and the control terminal of the third switch 130, the second terminal of the first pull-up resistor Ru1, the second terminal of the second pull-up resistor Ru2 and the first terminal of the third switch 130 are electrically connected to the input terminal of the power line VBUS, the second terminal of the first switch 110, the second terminal of the second switch 120 and the second terminal of the delay unit 140 are all grounded, and the second terminal of the third switch 130 is electrically connected to the output terminal of the power line VBUS.

The delay unit 140 is configured to delay the turning on of the second switch 120 when the initial input voltage received at the input end of the power line VBUS is greater than the protection voltage Vth, so as to turn on the first switch 110 before the second switch 120 is turned on.

Illustratively, the protection voltage Vth of the overvoltage protection circuit is 7V, that is, when the input end of the power line VBUS receives a voltage V smaller than Vth, the input end and the output end of the power line VBUS are conducted, and the voltage V can be output through the output end of the power line VBUS; when the input end of the power line VBUS receives the voltage V greater than or equal to Vth, the input end and the output end of the power line VBUS are disconnected, and the voltage V cannot be output through the output end of the power line VBUS.

If the power-on transient voltage is 5V, that is, the initial input voltage V0 received by the input terminal of the power line VBUS is 5V and is less than the protection voltage Vth, in this case, the bias current does not reach the on-state current of the first switch 110, so the first switch 110 is in the off-state, and the initial input voltage signal is transmitted to the control terminal of the second switch 120 through the first pull-up resistor Ru 1. The voltage of the control terminal of the second switch 120 is 5V, and the second terminal of the second switch 120 is grounded, so that the second switch 120 is turned on, the voltage of the first terminal of the second switch 120 is 0V, that is, the voltage of the control terminal of the third switch is 0V, at this time, the third switch 130 is turned on, because the two terminals of the third switch 130 are respectively connected to the input terminal and the output terminal of the power line VBUS, the input terminal and the output terminal of the power line VBUS are turned on, the initial input voltage signal can be output through the output terminal of the VBUS, and thus, the 5V voltage can be provided to the rear load.

If the power-on instant voltage is greater than or equal to 7V, that is, the initial input voltage V0 received by the input terminal of the power line VBUS is greater than or equal to 7V and greater than or equal to the protection voltage Vth, in this case, the initial input voltage signal is released to ground through the first pull-up resistor Ru1 and the delay unit 140, the voltage at the first terminal of the delay unit 140 gradually rises, and when the voltage at the first terminal of the delay unit 140 rises to the turn-on voltage of the second switch 120, the second switch 120 is turned on. However, in the process of the gradual voltage rise at the first end of the delay unit 140, the voltage does not rise to the turn-on voltage of the second switch 120, the first switch 110 starts to be turned on, and the initial input voltage signal is released to the ground through the first pull-up resistor Ru 1. In this process, the second switch 120 is always in the off state, and the voltage at the first terminal of the second switch 120 is at a high level, so that the third switch is always in the off state, the input terminal and the output terminal of the power line VBUS are disconnected, and the initial input voltage signal is not output through the output terminal of VBUS, thereby avoiding providing an excessively high voltage to the back-end load. In this way, the delay unit 140 delays the on-time of the second switch 120, and turns on the first switch 110 within the delay time, so that the second switch 120 is always in the off-state, and an instantaneous high-voltage signal is prevented from being output, thereby playing a role in protecting a back-end load.

If the working voltage received by the input terminal of the power line VBUS is 5V, and the working voltage is maintained for a period of time after the working voltage of 5V is received, the working voltage is suddenly increased to be greater than or equal to 7V, in this case, in the process of climbing the working voltage from 7V to 7.5V, the switching frequency of the first switch 110, the second switch 120 and the third switch 130 may reach 100MHz, that is, 10ns, and in the process of voltage continuing to climb, once the received working voltage exceeds 7V, the first switch 110 is turned on, the second switch 120 is turned off, the third switch 130 is turned off, and the total time is at most 30 ns. However, in the design of the general overvoltage protection circuit, the protection voltage of the overvoltage protection circuit is always at least 0.5V lower than the voltage which actually damages the rear-stage load, that is, the working voltage does not actually damage the rear-stage load during the process of climbing from 7V to 7.5V. Since the time required by the third switch 130 from turning on to turning off is at most 30ns, which is less than the time required by the working voltage to climb from 7V to 7.5V, i.e. the input end and the output end of the power line VBUS can be turned off during the climbing process of the working voltage from 7V to 7.5V, and the received working voltage is prevented from damaging the load at the rear stage.

It should be noted that the initial input voltage and the protection voltage in the above embodiments are exemplary illustrations, and are not intended to limit the disclosure.

In this embodiment, the overvoltage protection circuit includes: the circuit comprises a first switch, a second switch, a third switch, a first pull-up resistor, a second pull-up resistor and a time delay unit; the control end of the first switch is electrically connected with the input end of a power line, the first end of the first switch is respectively electrically connected with the first end of the first pull-up resistor, the first end of the time delay unit and the control end of the second switch, the first end of the second switch is respectively electrically connected with the first end of the second pull-up resistor and the control end of the third switch, the second end of the first pull-up resistor, the second end of the second pull-up resistor and the first end of the third switch are electrically connected with the input end of the power line, the second end of the first switch, the second end of the second switch and the second end of the time delay unit are all grounded, the second end of the third switch is electrically connected with the output end of the power line, the time delay unit can delay the conduction of the second switch when the initial input voltage received by the input end of the power line is greater than the protection voltage, so that the first switch is conducted before the second switch is conducted, the initial input voltage signal is released to the ground after passing through the first switch, the second switch is in a cut-off state, namely the third switch is cut off, so that an initial input voltage signal cannot be output from the output end of the power line, the rear-stage load can be protected, the rear-stage load is prevented from being broken down, overvoltage protection on the rear-stage load is realized, and therefore overvoltage protection can be realized through the three switches and the delay unit, and the cost of the overvoltage protection circuit can be reduced.

Optionally, fig. 2 is a schematic structural diagram of another overvoltage protection circuit provided in the present disclosure, and as shown in fig. 2, the overvoltage protection circuit 100 further includes: a voltage regulating unit 150.

A first end of the voltage regulating unit 150 is electrically connected to the input end of the power line VBUS, a second end of the voltage regulating unit 150 is electrically connected to the control end of the first switch 110, and a third end of the voltage regulating unit 150 is grounded.

And a voltage regulating unit 150 for regulating the protection voltage of the overvoltage protection circuit 100.

Specifically, the sum of the voltage between the first end and the second end of the voltage regulating unit 150 and the voltage between the second end and the third end of the voltage regulating unit 150 is the working voltage received by the input end of the power line VBUS. If the voltage between the first terminal and the second terminal of the voltage adjusting unit 150 decreases, the voltage between the second terminal and the third terminal of the voltage adjusting unit 150, that is, the voltage of the control terminal of the first switch 110 increases; if the voltage between the first terminal and the second terminal of the voltage adjusting unit 150 increases, the voltage between the second terminal and the third terminal of the voltage adjusting unit 150 decreases, that is, the voltage of the control terminal of the first switch 110 decreases. Therefore, the voltage of the control terminal of the first switch 110, i.e., the turn-on voltage of the first switch 110, can be adjusted by adjusting the resistance value between the first terminal and the second terminal of the voltage adjusting unit 150 and/or the resistance value between the second terminal and the third terminal of the voltage adjusting unit 150.

As can be seen from the above analysis, the on-voltage of the first switch 110 is the protection voltage of the overvoltage protection circuit 100, the working voltage is greater than the on-voltage of the first switch 110, the first switch 110 is turned on, the second switch 120 is turned off, the third switch 130 is turned off, and the input terminal and the output terminal of the power line VBUS are turned off; the operating voltage is less than the turn-on voltage of the first switch 110, the first switch 110 is turned off, the second switch 120 is turned on, the third switch 130 is turned on, and the input terminal and the output terminal of the power line VBUS are turned on.

In this embodiment, the first end of the voltage regulation unit is electrically connected to the input end of the power line, the second end of the voltage regulation unit is electrically connected to the control end of the first switch, and the voltage regulation unit can regulate the protection voltage of the overvoltage protection circuit, so that the applicability of the overvoltage protection circuit can be improved.

Optionally, fig. 3 is a schematic structural diagram of another overvoltage protection circuit provided in the present disclosure, and as shown in fig. 3, the delay unit 140 includes: a capacitance C.

A first end of the capacitor C is electrically connected to the first end of the first switch 110 and the control end of the second switch 120, respectively, and a second end of the capacitor C is grounded.

For example, as shown in fig. 3, if the initial input voltage V0 received by the input terminal of the power line VBUS is greater than or equal to 7V, the capacitor C is a charging circuit, and the initial input signal is transmitted to the capacitor C to charge the capacitor C, so that the voltage of the capacitor C gradually increases. When the voltage of the capacitor C is increased to the on-voltage of the second switch 120, the first switch 110 is turned on, and the charging process of the capacitor C is a process of delaying the turn-on of the second switch 120, thereby implementing the delayed turn-on of the second switch 120.

In this embodiment, the delay unit includes: the first end of the capacitor is respectively electrically connected with the first end of the first switch and the control end of the second switch, and the second end of the capacitor is grounded, so that the capacitor can store energy, the conduction time of the second switch is delayed, and the delayed conduction of the second switch is realized.

Optionally, with continued reference to fig. 3, the voltage regulating unit 150 includes: a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4.

The first end of the first resistor R1 is electrically connected to the input end of the power line VBUS, the second end of the first resistor R1 is electrically connected to the first end of the second resistor R2, the first end of the third resistor R3 and the first end of the fourth resistor R4, the second end of the second resistor R2 and the second end of the third resistor R3 are both grounded, and the second end of the fourth resistor R4 is electrically connected to the control end of the first switch 110.

Specifically, as shown in fig. 3, after the resistor between the control terminal and the second terminal of the first switch 110 is connected in series with the fourth resistor R4, the resistor is connected in parallel with the second resistor R2 and the third resistor R3, and then connected in series with the first resistor R1. The voltage of the control terminal of the first switch 110 can be reduced by increasing the resistance of the first resistor R1, the voltage of the control terminal of the first switch 110 can be reduced by increasing the resistance of the fourth resistor R4, and the voltage of the control terminal of the first switch 110 can be increased by increasing the second resistor R2 and/or the third resistor R3, so that the protection voltage of the overvoltage protection circuit 100 can be adjusted.

In this implementation, the first end of the first resistor is electrically connected to the input end of the power line, the second end of the first resistor is electrically connected to the first end of the second resistor, the first end of the third resistor and the first end of the fourth resistor, the second end of the second resistor and the second end of the third resistor are both grounded, and the second end of the fourth resistor is electrically connected to the control end of the first switch.

Optionally, fig. 4 is a schematic structural diagram of another overvoltage protection circuit provided by the present disclosure, as shown in fig. 4, the first switch 110 includes a first transistor Q1, a base b of the first transistor Q1 is electrically connected to a control terminal of the first switch 110, a collector c of the first transistor Q1 is electrically connected to a first terminal of the first switch 110, and an emitter e of the first transistor Q1 is electrically connected to a second terminal of the first switch 110.

The second switch 120 includes a second transistor Q2, a base b of the second transistor Q2 is electrically connected to a control terminal of the second switch 120, a collector c of the second transistor Q2 is electrically connected to a first terminal of the second switch 120, and an emitter e of the second transistor Q2 is electrically connected to a second terminal of the second switch 120.

Illustratively, as shown in fig. 4, the first transistor Q1 and the second transistor Q2 are NPN transistors. When the voltage of the base electrode b of the first triode Q1 meets the conducting condition, the collector electrode c and the emitter electrode e of the first triode Q1 are conducted, the voltage of the collector electrode c is pulled down, so that the voltages of the collector electrode c and the emitter electrode e are both 0, and the voltage signal is released to the ground through the first triode Q1. When the voltage of the base b of the second triode Q2 meets the conduction condition, the collector c and the emitter e of the second triode Q2 are conducted, the voltage of the collector c is pulled down, so that the voltages of the collector c and the emitter e are both 0, and the third switch 130 is conducted under the action of low level.

Optionally, with continued reference to fig. 4, the overvoltage protection circuit 100 further includes: a first pull-down resistor Rd1 and a second pull-down resistor Rd 2.

The first end of the first pull-down resistor Rd1 is electrically connected to the base b of the first transistor Q1, and the second end of the first pull-down resistor Rd1 is grounded. A first end of the second pull-down resistor Rd2 is electrically connected to the base b of the second transistor Q2, and a second end of the second pull-down resistor Rd2 is grounded.

Specifically, an emitter e of the first triode Q1 is grounded, that is, the first pull-down resistor Rd1 is connected in series between the base b and the emitter e of the first triode Q1, and the first pull-down resistor Rd1 reliably stops the first triode Q1 when the input is in a high-impedance state, so that the first triode Q1 is prevented from generating a false operation due to the influence of a noise signal, and the first triode Q1 is more reliably stopped. The emitter e of the second triode Q2 is grounded, that is, the second pull-down resistor Rd2 is connected in series between the base b and the emitter e of the second triode Q2, and the second pull-down resistor Rd2 reliably cuts off the second triode Q2 when the input of the second pull-down resistor Rd2 is in a high-impedance state, so that the second triode Q2 is prevented from generating false operation due to the influence of noise signals, and the second triode Q2 is cut off more reliably.

In this embodiment, the first end of the first pull-down resistor is electrically connected to the base of the first triode, and the second end of the first pull-down resistor is grounded. The first end of the second pull-down resistor is electrically connected with the base electrode of the second triode, the second end of the second pull-down resistor is grounded, and the resistor can be connected in series between the base electrode and the emitting electrode of the triode, so that the triode is prevented from generating misoperation under the influence of a noise signal, and the cut-off of the triode is more reliable.

Optionally, with continued reference to fig. 4, the overvoltage protection circuit 100 further includes: a current limiting resistor Rt.

The first end of the current limiting resistor Rt is electrically connected with the first end of the first pull-up resistor Ru1, and the second end of the current limiting resistor Rt is electrically connected with the base b of the second triode Q2.

Specifically, as shown in fig. 4, the base b of the second triode Q2 is electrically connected to the input terminal of the power line VBUS through the current limiting resistor Rt and the first pull-up resistor Ru1, and if the operating voltage received by VBUS is large, the operating voltage can be divided through the current limiting resistor Rt, so that the base current is reduced, the second triode Q2 is prevented from being broken down, and the second triode Q2 can be protected.

In this embodiment, the first end through current-limiting resistor is connected with the first end electricity of first pull-up resistance, and the second end of current-limiting resistor is connected with the control end electricity of second switch, can reduce the base electric current of second triode, avoids the second triode to be punctured, plays the effect of protection second triode.

Optionally, with continued reference to fig. 4, the third switch 130 includes a fet Q3, a gate g of the fet Q3 is electrically connected to a control terminal of the third switch 130, a drain d of the fet Q3 is electrically connected to a first terminal of the third switch 130, and a source s of the fet Q3 is electrically connected to a second terminal of the third switch 130.

Illustratively, as shown in fig. 4, the fet Q3 is a P-type fet, i.e., the fet Q3 is turned on when the gate g voltage is low. The input of power cord VBUS receives the operating voltage that is less than protection voltage, does not reach the turn-on voltage of first triode Q1 promptly, and first triode Q1 ends, and operating signal transmits to second triode Q2 for second triode Q2 switches on, then the voltage of second triode Q2's collecting electrode c is for drawing to the low level, and at this moment, field effect transistor Q3's grid g is the low level, and control switches on field effect transistor Q3, makes the input and the output of power cord VBUS switch on.

The present disclosure also provides an electronic device, fig. 5 is a schematic structural diagram of an overvoltage protection system provided by the present disclosure, and as shown in fig. 5, the overvoltage protection system 200 includes: a power supply line 210 and the overvoltage protection circuit 100 provided in any of the embodiments described above.

The overvoltage protection circuit 100 is electrically connected between the input and output of the power line 210.

If the working voltage received by the input end of the power line 210 is greater than the protection voltage, the input end and the output end of the overvoltage protection circuit 100 are disconnected, that is, the input end and the output end of the power line 210 are disconnected, so that the working voltage signal is prevented from being transmitted to the rear-stage load, and the rear-stage load is protected. If the working voltage received by the input terminal of the power line 210 is less than the protection voltage, the input terminal and the output terminal of the overvoltage protection circuit 100 are turned on, that is, the input terminal and the output terminal of the power line 210 are turned on, and the working voltage signal is transmitted to the rear-stage load to provide power for the rear-stage load.

The overvoltage protection system in this embodiment includes any one of the overvoltage protection circuits provided in the embodiments described above, and has the same beneficial effects and technical solutions as the overvoltage protection circuit, which are not described herein again.

Fig. 6 is a schematic structural diagram of an electronic device provided in the present disclosure, and as shown in fig. 5, the electronic device 300 includes: the load 310, the power line 210 and the overvoltage protection circuit 100 provided by any of the above embodiments.

The overvoltage protection circuit 100 is electrically connected between the input terminal and the output terminal of the power line 210, and the load 310 is electrically connected to the output terminal of the power line 210.

For example, if the working voltage received by the receiving end of the power line 210 is less than the protection voltage of the overvoltage protection circuit 100, the input end and the output end of the power line 210 are turned on, so that the working voltage signal is transmitted to the load 310 through the output end of the power line 210 to provide power to the load 310. If the working voltage received by the receiving end of the power line 210 is greater than the protection voltage of the overvoltage protection circuit 100, the input end and the output end of the power line 210 are disconnected, so that the working voltage signal is prevented from being transmitted to the load 310 through the output end of the power line 210, and the load is prevented from being damaged by the overlarge working voltage.

It should be noted that fig. 6 only exemplarily shows that the electronic device includes one load, in practical applications, a plurality of loads may be included, and each load may be connected in parallel or in series.

The electronic device in this embodiment includes any one of the overvoltage protection circuits provided in the above embodiments, and has the same beneficial effects and technical solutions as the overvoltage protection circuit, which are not described herein again.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing are merely exemplary embodiments of the present disclosure, which enable those skilled in the art to understand or practice the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. An overvoltage protection circuit, comprising: the circuit comprises a first switch, a second switch, a third switch, a first pull-up resistor, a second pull-up resistor and a time delay unit;

the control end of the first switch is electrically connected with the input end of a power line, the first end of the first switch is respectively electrically connected with the first end of the first pull-up resistor, the first end of the delay unit and the control end of the second switch, the first end of the second switch is respectively electrically connected with the first end of the second pull-up resistor and the control end of the third switch, the second end of the first pull-up resistor, the second end of the second pull-up resistor and the first end of the third switch are electrically connected with the input end of the power line, the second end of the first switch, the second end of the second switch and the second end of the delay unit are all grounded, and the second end of the third switch is electrically connected with the output end of the power line;

and the time delay unit is used for delaying the conduction of the second switch when the initial input voltage received by the input end of the power line is greater than the protection voltage so as to conduct the first switch before conducting the second switch.

2. The overvoltage protection circuit of claim 1, further comprising: a voltage regulating unit;

the first end of the voltage regulating unit is electrically connected with the input end of the power line, the second end of the voltage regulating unit is electrically connected with the control end of the first switch, and the third end of the voltage regulating unit is grounded;

and the voltage regulating unit is used for regulating the protection voltage of the overvoltage protection circuit.

3. The overvoltage protection circuit according to claim 1 or 2, wherein the delay unit comprises: a capacitor;

the first end of the capacitor is respectively electrically connected with the first end of the first switch and the control end of the second switch, and the second end of the capacitor is grounded.

4. The overvoltage protection circuit of claim 2, wherein the voltage regulation unit comprises: the circuit comprises a first resistor, a second resistor, a third resistor and a fourth resistor;

the first end of the first resistor is electrically connected with the input end of the power line, the second end of the first resistor is respectively electrically connected with the first end of the second resistor, the first end of the third resistor and the first end of the fourth resistor, the second end of the second resistor and the second end of the third resistor are both grounded, and the second end of the fourth resistor is electrically connected with the control end of the first switch.

5. The overvoltage protection circuit of claim 1 or 2, wherein the first switch comprises a first transistor, a base of the first transistor is electrically connected to a control terminal of the first switch, a collector of the first transistor is electrically connected to a first terminal of the first switch, and an emitter of the first transistor is electrically connected to a second terminal of the first switch;

the second switch comprises a second triode, the base electrode of the second triode is electrically connected with the control end of the second switch, the collector electrode of the second triode is electrically connected with the first end of the second switch, and the emitter electrode of the second triode is electrically connected with the second end of the second switch.

6. The overvoltage protection circuit of claim 5, further comprising: a first pull-down resistor and a second pull-down resistor;

the first end of the first pull-down resistor is electrically connected with the base electrode of the first triode, and the second end of the first pull-down resistor is grounded;

the first end of the second pull-down resistor is electrically connected with the base electrode of the second triode, and the second end of the second pull-down resistor is grounded.

7. The overvoltage protection circuit of claim 5, further comprising: a current limiting resistor;

the first end of the current-limiting resistor is electrically connected with the first end of the first pull-up resistor, and the second end of the current-limiting resistor is electrically connected with the base electrode of the second triode.

8. The overvoltage protection circuit of claim 5, wherein the third switch comprises a fet, a gate of the fet is electrically connected to a control terminal of the third switch, a drain of the fet is electrically connected to a first terminal of the third switch, and a source of the fet is electrically connected to a second terminal of the third switch.

9. An overvoltage protection system comprising a power supply line and an overvoltage protection circuit according to any one of claims 1 to 8;

the overvoltage protection circuit is electrically connected between the input end and the output end of the power line.

10. An electronic device comprising a load, a power supply line, and the overvoltage protection circuit of any one of claims 1-8;

the overvoltage protection circuit is electrically connected between the input end and the output end of the power line, and the load is electrically connected with the output end of the power line.

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