Delay switch circuit and electronic equipment with overvoltage protection

Abstract

The present application relates to a time-delay switch circuit and electronic device with overvoltage protection, and relates to the technical field of voltage protection. The power supply circuit applied to electronic devices includes an overvoltage detection unit, a delay unit, a control unit, and a switch unit; the input end of the overvoltage detection unit is connected to the external voltage input end VIN, the output end of the overvoltage detection unit is connected to the input end of the delay unit, the input end of the delay unit is also connected to the voltage input end, the output end of the delay unit is connected to the input end of the control unit, the output end of the control unit is connected to the control end of the switch unit, the ground end of the switch unit is connected to the ground end GND, the voltage end of the switch unit is connected to the negative power supply end VOUT‑ of the electronic device, and the positive power supply end VOUT+ of the electronic device is connected to the external voltage input end VIN. The present application has the effect of overvoltage protection for electronic devices.

Description

Technical Field

[0001] The present application relates to the technical field of voltage protection, and in particular to a time-delay switch circuit and electronic equipment with overvoltage protection. Background Art

[0002] With the development of science and technology, the application of electronic equipment is becoming more and more widely related to people's lives. The stability and safety of electronic equipment is the guarantee of our daily life and work.

[0003] At present, when electronic devices are working, the power supply that powers the electronic devices is affected by external factors, which may cause the voltage output by the power supply to be unstable, thereby affecting the operation of the electronic devices. Even excessively high voltage may damage the components inside the electronic devices, rendering the electronic devices unusable.

[0004] In the related art, a voltage detection circuit is generally provided for detecting the power supply voltage for powering electronic devices. However, since the time response for detecting the power supply voltage is relatively long and the voltage detection circuit cannot respond in time when the power supply generates a spike voltage, the spike voltage of the power supply voltage has already been input into the electronic device, causing the electronic device to be damaged by the spike voltage, thus affecting its use. Summary of the invention

[0005] In order to protect electronic equipment from overvoltage, the present application provides a time-delay switch circuit and electronic equipment with overvoltage protection.

[0006] In a first aspect, the present application provides a time-delay switch circuit with overvoltage protection, which adopts the following technical solution:

[0007] A time-delay switch circuit with overvoltage protection is applied to the power supply circuit of electronic equipment, comprising an overvoltage detection unit, a time-delay unit, a control unit and a switch unit;

[0008] The input end of the overvoltage detection unit is connected to the external voltage input end VIN, the output end of the overvoltage detection unit is connected to the input end of the delay unit, the input end of the delay unit is also connected to the voltage input end, the output end of the delay unit is connected to the input end of the control unit, the output end of the control unit is connected to the control end of the switch unit, the ground end of the switch unit is connected to the ground end GND, the voltage end of the switch unit is connected to the negative power supply terminal VOUT- of the electronic device, and the positive power supply terminal VOUT+ of the electronic device is connected to the external voltage input terminal VIN;

[0009] The overvoltage detection unit is used to sample the external voltage of the external voltage input terminal VIN, compare the external voltage with a preset voltage, and output a detection signal to the delay unit, wherein the detection signal includes an overvoltage signal and a normal signal;

[0010] The delay unit is used to output a corresponding control voltage to the control unit according to the detection signal;

[0011] The control unit is used to control the switch unit to be turned on or off according to the control voltage and the preset voltage.

[0012] By adopting the above technical solution, when the overvoltage detection unit detects that the voltage input to the external voltage input terminal VIN is too high, the overvoltage detection unit outputs an overvoltage signal, and the delay unit outputs a corresponding control voltage according to the received overvoltage signal, so that the control unit controls the switch unit to turn off according to the corresponding control voltage, thereby protecting the electronic device.

[0013] Optionally, the delay unit includes a timing subunit, a voltage regulating subunit and an output control voltage subunit; the input end of the timing subunit is respectively connected to the external voltage input end VIN, the output end of the voltage regulating subunit and the control end of the output control voltage subunit, the ground end of the timing subunit is connected to the ground end GND, the control end of the voltage regulating subunit is connected to the output end of the overvoltage detection unit, the ground end of the voltage regulating subunit is connected to the ground end GND, the input end of the output control voltage subunit is connected to the external voltage input end VIN, and the output end of the output control voltage subunit is connected to the control unit.

[0014] By adopting the above technical solution, by determining the parameters of the timing sub-unit according to the type of electronic equipment, the detection time of the overvoltage detection unit can be controlled, so that the overvoltage detection unit can fully detect the sampling voltage; at the same time, when the overvoltage detection unit outputs an overvoltage signal, the voltage adjustment sub-unit adjusts the control voltage output by the delay unit, so that the control unit controls the switch unit to shut down according to the received control voltage, thereby protecting the electronic equipment.

[0015] Optionally, the overvoltage detection unit includes a sampling subunit and a comparing subunit, the input end of the sampling subunit is connected to the external voltage input end VIN, the output end of the sampling subunit is connected to the input end of the comparing subunit, and the output end of the comparing subunit is connected to the input end of the delay unit.

[0016] By adopting the above technical solution, the sampling subunit samples the voltage inputted by the external voltage input terminal VIN, and the comparing subunit judges the sampled voltage, thereby achieving the purpose of judging whether the external voltage input terminal VIN is over-voltage.

[0017] Optionally, the comparison subunit includes a comparator U1 and a capacitor C3, the non-inverting input terminal of the comparator U1 is connected to the sampling subunit, the inverting input terminal of the comparator U1 is connected to a preset voltage providing unit, the output terminal of the comparator U1 is connected to the delay unit, one end of the capacitor C3 is connected to the inverting input terminal of the comparator U1, and the other end of the capacitor C3 is connected to the output terminal of the comparator U1;

[0018] The preset voltage providing unit is used to provide a reference voltage for the comparator U1.

[0019] By adopting the above technical solution, when comparing the sampled voltage with the preset voltage, the capacitor C3 can provide negative feedback to the comparator U1, thereby reducing the possibility of misjudgment caused by voltage interference.

[0020] Optionally, the control unit includes a resistor R1, a resistor R2, a resistor R3 and a comparator U2; one end of the resistor R1 is connected to the delay unit, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the non-inverting input end of the comparator U2, the other end of the resistor R2 is connected to the ground terminal GND, the inverting input end of the comparator U2 is connected to a preset voltage providing unit, the output end of the comparator U2 is connected to the control end of the switch unit, one end of the resistor R3 is connected to the delay unit, and the other end of the resistor R3 is connected to the output end of the comparator U2;

[0021] The preset voltage providing unit is used to provide a reference voltage for the comparator U2.

[0022] Optionally, the switch unit includes a field effect transistor Q3, the gate of the field effect transistor Q3 is connected to the output end of the control unit, the source of the field effect transistor Q3 is connected to the ground end GND, and the drain of the field effect transistor Q3 is connected to the voltage output end of the electronic device.

[0023] By adopting the above technical solution, when the control unit outputs a high level signal, the switch unit is turned on to enable the electronic device to work normally, and when the control unit outputs a low level signal, the switch unit is turned off to protect the load in the electronic device.

[0024] Optionally, the preset voltage providing unit includes a mirror constant current source, a resistor R7 and a resistor R8, the input end of the mirror constant current source is connected to the external power supply end VCC, the output end of the mirror constant current source is connected to one end of the resistor R7, the other end of the resistor R7 is connected to one end of the resistor R8, the other end of the resistor R8 is connected to the ground end GND, and the connection point between the resistor R7 and the resistor R8 is connected to the input end of the overvoltage detection unit.

[0025] By adopting the above technical solution, the mirror constant current source can provide a stable current, and can provide a stable voltage after passing through the resistor R7 and the resistor R8, so that the overvoltage detection unit can detect more accurately.

[0026] In a second aspect, the present application provides an electronic device, which adopts the following technical solution:

[0027] An electronic device comprises the time-delay switch circuit with overvoltage protection as described in the first aspect.

[0028] In summary, the present application includes at least one of the following beneficial technical effects:

[0029] 1. When the overvoltage detection unit detects that the voltage inputted by the external voltage input terminal VIN is too high, the overvoltage detection unit outputs an overvoltage signal, and the delay unit outputs a corresponding control voltage according to the received overvoltage signal, so that the control unit controls the switch unit to turn off according to the corresponding control voltage, thereby protecting the electronic equipment;

[0030] 2. By determining the parameters of the timing subunit according to the type of electronic equipment, the detection time of the overvoltage detection unit can be controlled so that the overvoltage detection unit can fully detect the sampled voltage; at the same time, when the overvoltage detection unit outputs an overvoltage signal, the voltage adjustment subunit adjusts the control voltage output by the delay unit, so that the control unit controls the switch unit to turn off according to the received control voltage, thereby protecting the electronic equipment;

[0031] 3. When the control unit outputs a high-level signal, the switch unit is turned on, allowing the electronic device to work normally. When the control unit outputs a low-level signal, the switch unit is turned off, protecting the load in the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural block diagram of an embodiment of the present application.

[0033] Figure 2 It is a circuit schematic diagram of an embodiment of the present application.

[0034] Explanation of the accompanying drawings: 1. Overvoltage detection unit; 11. Sampling subunit; 12. Comparison subunit; 2. Delay unit; 21. Timing subunit; 22. Adjustment voltage subunit; 23. Output control voltage subunit; 3. Control unit; 4. Switch unit; 5. Preset voltage providing unit. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-2 It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] The present application embodiment discloses a time-delay switch circuit with overvoltage protection. Figure 1 and Figure 2 The time-delay switch circuit with overvoltage protection includes an overvoltage detection unit 1, a delay unit 2, a control unit 3 and a switch unit 4.

[0037] In this embodiment, the input end of the overvoltage detection unit 1 is connected to the external voltage input end VIN, the output end of the overvoltage detection unit 1 is connected to the input end of the delay unit 2, the input end of the delay unit 2 is also connected to the external voltage input end VIN, the output end of the delay unit 2 is connected to the input end of the control unit 3, the output end of the control unit 3 is connected to the control end of the switch unit 4, the ground end of the switch unit 4 is connected to the ground end GND, the voltage end of the switch unit 4 is connected to the negative power supply terminal VOUT- of the load, and the positive power supply terminal VOUT+ of the load is connected to the external voltage input terminal VIN.

[0038] When it is necessary to power the electronic device, the overvoltage detection unit 1 samples the voltage input from the external input terminal to obtain a sampled voltage, and then compares the sampled voltage with a preset voltage. When the sampled voltage is greater than the preset voltage, the overvoltage detection unit 1 outputs a detection signal, and outputs the detection signal to the delay unit 2. The delay unit 2 outputs a corresponding control voltage to the control unit 3 according to the received detection signal. The control unit 3 compares the received control voltage with the preset voltage, and outputs a control signal to the switch unit 4. The switch unit 4 is turned on or off according to the received control signal, thereby controlling whether the external voltage is input into the electronic device, thereby protecting the electronic device.

[0039] As an optional implementation of this embodiment, the overvoltage detection unit 1 includes a sampling subunit 11 and a comparing subunit 12, the input end of the sampling subunit 11 is connected to the external voltage input end VIN, the output end of the sampling subunit 11 is connected to the input end of the comparing subunit 12, the input end of the comparing subunit 12 is also connected to the preset voltage providing unit 5, and the output end of the comparing subunit 12 is connected to the delay unit 2.

[0040] Specifically, the sampling subunit 11 includes a resistor R5 and a resistor R6; one end of the resistor R5 is connected to the external voltage input terminal VIN, the other end of the resistor R5 is respectively connected to one end of the resistor R6 and the input terminal of the comparison subunit 12, and the other end of the resistor R6 is connected to the ground terminal GND.

[0041] The comparison subunit 12 includes a comparator U1 and a capacitor C3; the non-inverting input terminal of the comparator U1 is connected to the connection point of the resistor R5 and the resistor R6, the inverting input terminal of the comparator U1 is connected to the preset voltage providing unit 5, the output terminal of the comparator U1 is connected to the delay unit 2, the inverting input terminal of the comparator U1 is also connected to one end of the capacitor C3, and the other end of the capacitor C3 is connected to the output terminal of the comparator U1.

[0042] Specifically, the capacitor C3 can provide negative feedback to the comparator U1 , thereby reducing the influence of the interference voltage on the comparator U1 , thereby reducing the possibility of malfunction.

[0043] In this embodiment, when the overvoltage detection unit 1 is required to detect the voltage input to the external voltage input terminal VIN, the sampling subunit 11 samples the voltage input to the external input terminal to obtain a sampled voltage, and inputs the sampled voltage to the non-inverting input terminal of the comparator U1. At this time, the preset voltage providing unit 5 outputs a preset voltage to the inverting input terminal of the comparator U1. The comparator U1 compares the sampled voltage input to the non-inverting input terminal with the preset voltage input to the inverting input terminal. When the sampled voltage is greater than the preset voltage, it indicates that the voltage of the external voltage input terminal VIN is in an overvoltage state. At this time, the comparator U1 outputs a high-level signal to the delay unit 2, so that the delay unit 2 outputs a first control voltage to the control unit 3. The control unit 3 controls the switch unit 4 to turn off according to the received first control voltage, thereby protecting the electronic device.

[0044] When the sampling voltage is less than the preset voltage, it indicates that the voltage of the external voltage input terminal VIN is in a normal state. At this time, the comparator U1 outputs a low level to the delay unit 2, so that the delay unit 2 outputs a second control voltage to the control unit 3. The control unit 3 controls the switch unit 4 to turn on according to the received second control voltage, so that the electronic device can operate normally.

[0045] Reference Figure 1 and Figure 2As an optional implementation of this embodiment, the preset voltage providing unit 5 includes a mirror constant current source, a resistor R7 and a resistor R8; the input end of the mirror constant current source is connected to the power supply end VCC, the output end of the mirror constant current source is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the ground end GND, and the connection point of the resistor R1 and the resistor R2 is connected to the inverting input end of the comparator U1.

[0046] Furthermore, the mirror constant current source includes a MOS tube M1A and a MOS tube M1B, the drain of the MOS tube M1A is connected to the external power supply terminal VCC, the source of the MOS tube M1A is connected to the ground terminal GND, the gate of the MOS tube M1A is respectively connected to the external power supply terminal VCC and the gate of the MOS tube M1B, the source of the MOS tube M1B is connected to the ground terminal GND, and the drain of the MOS tube M1B is connected to the resistor R7.

[0047] Specifically, when a preset voltage needs to be provided, the mirror constant current source provides a stable current to the preset voltage providing unit 5 , and the mirror constant current source is connected in series with the resistors R7 and R8 to provide a stable preset voltage to the comparison subunit 12 .

[0048] As an optional implementation of this embodiment, the delay unit 2 includes a timing subunit 21, a voltage adjustment subunit and an output control voltage subunit 23; the input end of the timing subunit 21 is respectively connected to the external voltage input end VIN, the output end of the voltage adjustment subunit and the control end of the output control voltage subunit 23, the ground end of the timing subunit 21 is connected to the ground end GND, the control end of the voltage adjustment subunit is connected to the output end of the comparison subunit 12, the ground end of the voltage adjustment subunit is connected to the ground end GND, the input end of the output control voltage subunit 23 is connected to the external voltage input end VIN, and the output end of the output control voltage subunit 23 is connected to the control unit 3.

[0049] Specifically, the timing subunit 21 includes a resistor R4 and a capacitor C2, one end of the resistor R4 is connected to the external voltage input terminal VIN, the other end of the resistor R4 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the ground terminal GND.

[0050] The voltage regulating subunit includes a transistor Q1 , a base of the transistor Q1 is connected to the output end of the comparator U1 , an emitter of the transistor Q1 is connected to the ground GND, and a collector of the transistor Q1 is connected to the connection point of the resistor R4 and the capacitor C2 .

[0051] The output control voltage subunit 23 includes a transistor Q2 , the base of the transistor Q2 is connected to the collector of the transistor Q1 , the collector of the transistor Q2 is connected to the external voltage input terminal VIN, and the emitter of the transistor Q2 is connected to the input terminal of the control unit 3 .

[0052] In this embodiment, by adjusting the resistance value of the resistor R4 and the capacity of the capacitor C2, the conduction time of the transistor Q2 can be extended, thereby providing sufficient comparison time for the comparison subunit 12 to perform comparison, thereby reducing the possibility of misjudgment of the comparison subunit 12 due to a brief change in the peak value of the external voltage input terminal VIN.

[0053] When the overvoltage detection unit 1 compares the sampled voltage with the preset voltage, the voltage input from the external voltage input terminal VIN charges the capacitor C2 through the resistor R4; when the overvoltage detection unit 1 completes the comparison and outputs the detection signal, if the overvoltage detection unit 1 outputs an overvoltage signal, the transistor Q1 is turned on, pulling down the base voltage of the transistor Q2, thereby reducing the voltage of the emitter of the transistor Q2, and outputting the first control voltage to the control unit 3; if the overvoltage detection unit 1 outputs a normal signal, the transistor Q2 is turned off, and the base voltage of the transistor Q2 is equal to the charging voltage of the capacitor C2, and at this time the transistor Q2 outputs the second control voltage to the control unit 3.

[0054] In this embodiment, the transistor Q1 and the transistor Q2 are both NPN type.

[0055] As an optional implementation of this embodiment, the control unit 3 includes a comparator U2, a resistor R1, a resistor R2 and a resistor R3; one end of the resistor R1 is connected to the emitter of the transistor Q2, the other end of the resistor R1 is respectively connected to the in-phase input terminal of the comparator U2 and one end of the resistor R2, the other end of the resistor R2 is connected to the ground terminal GND, the inverting input terminal of the comparator U2 is connected to the connection point of the resistor R7 and the resistor R8, the output end of the comparator U2 is respectively connected to the control end of the switch unit 4 and one end of the resistor R3, and the other end of the resistor R3 is connected to one end of the resistor R1.

[0056] In this embodiment, the resistor R3 acts as a positive feedback to the comparator U2 , and at the same time accelerates the high level output of the comparator U2 , reducing the influence of the voltage fluctuation output by the comparator U2 on the switch unit 4 .

[0057] As an optional implementation of this embodiment, the switching unit 4 includes a field effect transistor Q3, the gate of the field effect transistor Q3 is connected to the output end of the comparator U2, the drain of the field effect transistor Q3 is connected to the negative power supply terminal VOUT- of the electronic device, and the source of the field effect transistor Q3 is connected to the ground terminal GND.

[0058] Specifically, the field effect transistor Q3 is an N-channel enhancement type field effect transistor.

[0059] When the delay unit 2 outputs the first control voltage to the non-inverting input terminal of the comparator U2, the first control voltage is less than the preset voltage. At this time, the voltage of the external voltage input terminal VIN is in an overvoltage state, and the comparator U2 outputs a low-level signal to control the field effect transistor Q3 to be cut off. The load in the electronic device cannot form a power supply circuit, thereby protecting the load and components in the electronic device.

[0060] When the delay unit 2 outputs the second control voltage to the non-inverting input terminal of the comparator U2, the second control voltage is greater than the preset voltage. At this time, the voltage input to the external voltage input terminal VIN is in a normal state, and the comparator U2 outputs a high-level signal to control the field effect transistor Q3 to be turned on. The load in the electronic device constitutes a power supply circuit, and the electronic device works normally.

[0061] The implementation principle of a delay switch circuit with overvoltage protection in an embodiment of the present application is as follows: when the sampling subunit 11 of the overvoltage detection unit 1 samples the voltage of the external voltage input terminal VIN and inputs it to the non-inverting input terminal of the comparator U1, the comparator U1 compares the sampled voltage with the preset voltage. When the sampled voltage is greater than the preset voltage, the comparator U1 outputs an overvoltage signal to the transistor Q1, the transistor Q1 is turned on, and the transistor Q1 pulls down the charging voltage of the capacitor C2, thereby pulling down the base voltage of the transistor Q2, and then the transistor Q2 outputs a first control voltage to the non-inverting input terminal of the comparator U2. The comparator U2 receives the first control voltage and outputs a low-level signal. The field effect transistor Q3 receives the low-level signal and is in a cut-off state, thereby protecting the load and components in the electronic device.

[0062] An embodiment of the present application also provides an electronic device, which includes the above-mentioned delay switch circuit with overvoltage protection and a load, wherein the negative power terminal VOUT- of the load is connected to the drain of the field effect transistor Q3, and the positive power terminal VOUT+ of the load is connected to the external voltage input terminal VIN.

[0063] When the voltage inputted by the external voltage input terminal VIN is too high, the switch unit 4 is disconnected to protect the load.

[0064] The above are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Any feature disclosed in this specification (including the abstract and drawings), unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

Claims

1. A time-delay switch circuit with overvoltage protection, characterized in that: A power supply circuit applied to electronic equipment, comprising an overvoltage detection unit (1), a delay unit (2), a control unit (3) and a switch unit (4); The input end of the overvoltage detection unit (1) is connected to the external voltage input end VIN, the output end of the overvoltage detection unit (1) is connected to the input end of the delay unit (2), the input end of the delay unit (2) is also connected to the voltage input end, the output end of the delay unit (2) is connected to the input end of the control unit (3), the output end of the control unit (3) is connected to the control end of the switch unit (4), the ground end of the switch unit (4) is connected to the ground end GND, the voltage end of the switch unit (4) is connected to the negative power supply end VOUT- of the electronic device, and the positive power supply end VOUT+ of the electronic device is connected to the external voltage input end VIN; The overvoltage detection unit (1) is used to sample the external voltage of the external voltage input terminal VIN, compare the external voltage with a preset voltage, and output a detection signal to the delay unit (2), wherein the detection signal includes an overvoltage signal and a normal signal; The delay unit (2) is used to output a corresponding control voltage to the control unit (3) according to the detection signal; the delay unit (2) comprises a timing subunit (21), a voltage regulating subunit (22) and an output control voltage subunit (23); the input end of the timing subunit (21) is respectively connected to the external voltage input end VIN, the output end of the voltage regulating subunit (22) and the control end of the output control voltage subunit (23); the ground end of the timing subunit (21) is connected to the ground end GND; the control end of the voltage regulating subunit (22) is connected to the output end of the overvoltage detection unit (1); the ground end of the voltage regulating subunit (22) is connected to the ground end GND; the input end of the output control voltage subunit (23) is connected to the external voltage input end VIN; and the output end of the output control voltage subunit (23) is connected to the control unit (3); The control unit (3) is used to control the switch unit (4) to be turned on or off according to the control voltage and the preset voltage; The control unit (3) comprises a resistor R1, a resistor R2, a resistor R3 and a comparator U2; one end of the resistor R1 is connected to the output end of the output control voltage subunit (23), the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the non-inverting input end of the comparator U2, the other end of the resistor R2 is connected to the ground terminal GND, the inverting input end of the comparator U2 is connected to a preset voltage providing unit (5), the output end of the comparator U2 is connected to the control end of the switch unit (4), one end of the resistor R3 is connected to the output end of the output control voltage subunit (23), and the other end of the resistor R3 is connected to the output end of the comparator U2; the preset voltage providing unit (5) is used to provide a reference voltage for the comparator U2.

2. The time-delay switch circuit with overvoltage protection according to claim 1, characterized in that: The overvoltage detection unit (1) comprises a sampling subunit (11) and a comparing subunit (12); the input end of the sampling subunit (11) is connected to the external voltage input end VIN; the output end of the sampling subunit (11) is connected to the input end of the comparing subunit (12); and the output end of the comparing subunit (12) is connected to the input end of the delay unit (2).

3. The time-delay switch circuit with overvoltage protection according to claim 2, characterized in that: The comparison subunit (12) comprises a comparator U1 and a capacitor C3, the non-inverting input terminal of the comparator U1 is connected to the sampling subunit (11), the inverting input terminal of the comparator U1 is connected to a preset voltage providing unit (5), the output terminal of the comparator U1 is connected to the delay unit (2), one end of the capacitor C3 is connected to the inverting input terminal of the comparator U1, and the other end of the capacitor C3 is connected to the output terminal of the comparator U1; The preset voltage providing unit (5) is used to provide a reference voltage for the comparator U1.

4. The time-delay switch circuit with overvoltage protection according to claim 1, characterized in that: The switch unit (4) comprises a field effect transistor Q3, the gate of the field effect transistor Q3 is connected to the output end of the control unit (3), the source of the field effect transistor Q3 is connected to the ground end GND, and the drain of the field effect transistor Q3 is connected to the voltage output end of the electronic device.

5. The time-delay switch circuit with overvoltage protection according to claim 3 or 1, characterized in that: The preset voltage providing unit (5) comprises a mirror image constant current source, a resistor R7 and a resistor R8, wherein the input end of the mirror image constant current source is connected to an external power supply end VCC, the output end of the mirror image constant current source is connected to one end of the resistor R7, the other end of the resistor R7 is connected to one end of the resistor R8, the other end of the resistor R8 is connected to a ground end GND, and the connection point between the resistor R7 and the resistor R8 is connected to the input end of the overvoltage detection unit (1).

6. An electronic device, characterized in that: It comprises a time-delay switch circuit with overvoltage protection as claimed in any one of claims 1 to 5.

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