Electric equipment and power supply protection circuit thereof

Abstract

The utility model discloses an electric device and a power supply protection circuit thereof, belonging to the field of power supply protection, in which a PMOS (P-channel Metal Oxide Semiconductor) is used as a control switch between a power adapter and a power supply input interface of the electric device, and an under-voltage protection module can be used for protecting the power adapter when the output voltage of the power adapter is greater than a first threshold value. When the output voltage of the power adapter is larger than a first threshold value, the PMOS is switched on by controlling the grid voltage of the PMOS, when the output voltage of the power adapter is smaller than the first threshold value, the PMOS is switched off by controlling the grid voltage of the PMOS, and when the output voltage of the power adapter is larger than a second threshold value, the overvoltage protection module can switch off the PMOS by controlling the grid voltage of the PMOS. That is, when the output voltage of the power adapter is out of the range from the first threshold value to the second threshold value, the PMOS is cut off, overvoltage and undervoltage protection of the electric equipment is achieved, the structure is simple, the number of devices is reduced, and cost is low.

Description

Technical Field

[0001] The utility model relates to the field of power supply protection, in particular to a power supply protection circuit. The utility model also relates to an electrical equipment. Background Art

[0002] The power adapter can rectify the AC power into DC power and then supply power to the electrical equipment. Due to unstable power supply voltage and other reasons, the voltage value of the DC power supplied to the electrical equipment is likely to exceed the normal range, which will affect the electrical equipment and even cause damage to the electrical equipment. At present, there is a lack of a mature power supply protection circuit. Electrical equipment usually needs to use expensive power supply protection chips to avoid the impact of voltage values ​​beyond the normal range on the electrical equipment, which is costly.

[0003] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present. Utility Model Content

[0004] The purpose of the utility model is to provide a power supply protection circuit. Through the cooperation of an undervoltage protection module and an overvoltage protection module, the PMOS can be cut off when the output voltage of a power adapter is outside the range of a first threshold to a second threshold, thereby realizing overvoltage and undervoltage protection for electrical equipment, and the structure is simple, the number of components is reduced, and the cost is low; another purpose of the utility model is to provide an electrical equipment including the above-mentioned power supply protection circuit. Through the cooperation of an undervoltage protection module and an overvoltage protection module, the PMOS can be cut off when the output voltage of the power adapter is outside the range of a first threshold to a second threshold, thereby realizing overvoltage and undervoltage protection for electrical equipment, and the structure is simple, the number of components is reduced, and the cost is low.

[0005] In order to solve the above technical problems, the utility model provides a power supply protection circuit, which is applied to electrical equipment, including:

[0006] A PMOS, a source electrode connected to the output terminal of the power adapter, and a drain electrode connected to the power input interface of the power-consuming device;

[0007] an undervoltage protection module, connected to the output end of the power adapter, the source of the PMOS, the gate of the PMOS and a power ground respectively, and used to control the gate voltage of the PMOS to be a preset voltage-divided value of the output voltage of the power adapter when the output voltage of the power adapter is greater than a first threshold, and to control the gate voltage of the PMOS to be equal to the source voltage when the output voltage of the power adapter is less than the first threshold;

[0008] an overvoltage protection module, connected to the output end of the power adapter, the source of the PMOS, the gate of the PMOS and a power ground respectively, and used for controlling the gate voltage of the PMOS to be equal to the source voltage when the output voltage of the power adapter is greater than a second threshold;

[0009] The second threshold is greater than the first threshold.

[0010] On the other hand, the undervoltage protection module includes a first recoverable diode, a first current limiting resistor, a first transistor, a first voltage dividing resistor and a second voltage dividing resistor;

[0011] The cathode of the first recoverable diode is respectively connected to the output end of the power adapter, the first end of the first voltage-dividing resistor and the source of the PMOS, the anode of the first recoverable diode is connected to the first end of the first current-limiting resistor, the second end of the first current-limiting resistor is connected to the base of the first transistor, the second end of the first voltage-dividing resistor is respectively connected to the gate of the PMOS and the first end of the second voltage-dividing resistor, the second end of the second voltage-dividing resistor is connected to the collector of the first transistor, and the emitter of the first transistor is grounded.

[0012] On the other hand, the undervoltage protection module further includes a first pull-down resistor;

[0013] The first end of the first pull-down resistor is connected to the second end of the first current limiting resistor and the base of the first transistor respectively, and the second end of the first pull-down resistor is grounded.

[0014] On the other hand, the overvoltage protection module includes a first pull-up resistor, a second recoverable diode, a second current limiting resistor and a second transistor;

[0015] The first end of the first pull-up resistor is respectively connected to the output end of the power adapter, the emitter of the second transistor, the first end of the first voltage-dividing resistor and the source of the PMOS, the second end of the first pull-up resistor is respectively connected to the cathode of the second recoverable diode and the first end of the second current-limiting resistor, the anode of the second recoverable diode is grounded, the second end of the second current-limiting resistor is connected to the base of the second transistor, and the collector of the second transistor is respectively connected to the second end of the first voltage-dividing resistor and the gate of the PMOS.

[0016] On the other hand, both the first recoverable diode and the second recoverable diode are zener diodes.

[0017] On the other hand, the power supply protection circuit also includes a circuit substrate;

[0018] The PMOS, the undervoltage protection module and the overvoltage protection module are arranged on the circuit substrate.

[0019] On the other hand, the power supply protection circuit also includes:

[0020] The delay protection circuit is respectively connected to the source of the PMOS, the gate of the PMOS and the power ground, and is used to control the voltage of the gate of the PMOS to drop from the output voltage of the power adapter to the preset voltage division value when connected to the power adapter.

[0021] On the other hand, the delay protection circuit includes a capacitor;

[0022] The first end of the capacitor is connected to the source of the PMOS, and the second end of the capacitor is connected to the gate of the PMOS.

[0023] In order to solve the above technical problems, the utility model also provides an electrical device, including an electrical device body, and also including:

[0024] The power supply protection circuit as described above is connected to the electrical equipment body.

[0025] The utility model provides a power supply protection circuit. Considering that the on-off state of PMOS can be changed by controlling the voltage between the gate and the source of PMOS, the utility model uses PMOS as a control switch between a power adapter and a power input interface of an electric device. The undervoltage protection module can turn on PMOS by controlling the gate voltage of PMOS when the output voltage of the power adapter is greater than a first threshold value, and turn off PMOS by controlling the gate voltage of PMOS when the output voltage of the power adapter is less than the first threshold value. The overvoltage protection module can turn off PMOS by controlling the gate voltage of PMOS when the output voltage of the power adapter is greater than a second threshold value, that is, PMOS is turned off when the output voltage of the power adapter is outside the range from the first threshold value to the second threshold value, thereby realizing overvoltage and undervoltage protection of the electric device, and has a simple structure, reduced components and low cost.

[0026] The utility model also provides an electrical device having the same beneficial effects as the above power supply protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the relevant technologies and drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of the structure of a power supply protection circuit provided by the utility model;

[0029] Figure 2 A structural schematic diagram of another power supply protection circuit provided by the utility model;

[0030] Figure 3 A schematic diagram of a curve of voltage across a capacitor provided by the utility model. DETAILED DESCRIPTION

[0031] The core of the utility model is to provide a power supply protection circuit. Through the cooperation of the undervoltage protection module and the overvoltage protection module, the PMOS can be cut off when the output voltage of the power adapter is outside the range of the first threshold to the second threshold, thereby realizing overvoltage and undervoltage protection for the electrical equipment, and the structure is simple, the number of components is reduced, and the cost is low; another core of the utility model is to provide an electrical equipment including the above-mentioned power supply protection circuit. Through the cooperation of the undervoltage protection module and the overvoltage protection module, the PMOS can be cut off when the output voltage of the power adapter is outside the range of the first threshold to the second threshold, thereby realizing overvoltage and undervoltage protection for the electrical equipment, and the structure is simple, the number of components is reduced, and the cost is low.

[0032] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] Please refer to Figure 1 , Figure 1 A schematic diagram of a power supply protection circuit provided by the utility model, the power supply protection circuit comprises:

[0034] PMOS 1, the source is connected to the output terminal of the power adapter, and the drain is connected to the power input interface of the power-consuming device;

[0035] An undervoltage protection module 2 is respectively connected to the output end of the power adapter, the source of the PMOS 1, the gate of the PMOS 1 and the power ground, and is used to control the gate voltage of the PMOS 1 to be a preset voltage-divided value of the output voltage of the power adapter when the output voltage of the power adapter is greater than a first threshold value, and to control the gate voltage of the PMOS 1 to be equal to the source voltage when the output voltage of the power adapter is less than the first threshold value;

[0036] An overvoltage protection module 3 is respectively connected to the output end of the power adapter, the source of the PMOS 1, the gate of the PMOS 1 and the power ground, and is used to control the gate voltage of the PMOS 1 to be equal to the source voltage when the output voltage of the power adapter is greater than the second threshold;

[0037] The second threshold is greater than the first threshold.

[0038] Specifically, considering the technical problems in the above background technology, and considering that PMOS 1 (Positivechannel Metal Oxide Semiconductor, P-channel metal oxide semiconductor field effect transistor) is suitable for controlling the on-off of a power supply circuit, and the on-off state of PMOS 1 can be changed by controlling the voltage between the gate and the source of PMOS 1, the utility model intends to design a power supply protection circuit for an electrical device based on PMOS 1. Considering that the on-off state of PMOS 1 depends on the voltage difference between the gate and the source, the utility model designs an undervoltage protection module 2 and an overvoltage protection module 3 both connected to the gate, source and power ground of PMOS 1. The undervoltage protection module 2 can control the gate voltage of PMOS 1 to be a preset voltage division value of the output voltage of the power adapter when the output voltage of the power adapter is greater than a first threshold value, so that PMOS 1 is turned on. When the output voltage of the power adapter is less than the first threshold value, the gate voltage of PMOS 1 is controlled to be equal to the source voltage, so that PMOS 1 is turned off. The overvoltage protection module 3 can control PMOS 1 to be equal to the source voltage when the output voltage of the power adapter is greater than a second threshold value. 1 is equal to the source voltage so that PMOS 1 is turned off; that is, through the undervoltage protection module 2 and the overvoltage protection module 3, the PMOS is turned on when the output voltage of the power adapter is within the range from the first threshold to the second threshold, and is turned off when it is outside the range from the first threshold to the second threshold, thereby achieving undervoltage protection and overvoltage protection.

[0039] Specifically, for PMOS 1, it can be turned on when the voltage difference between the gate and the source is less than the turn-on threshold voltage, and it can be turned off when it is not less than the turn-on threshold voltage. Therefore, the undervoltage protection module 2 and the overvoltage protection module 3 can execute the above control logic to make PMOS 1 turn on when the output voltage of the power adapter is within the range of the first threshold to the second threshold, and turn off when it is outside the range of the first threshold to the second threshold, thereby realizing undervoltage protection and overvoltage protection.

[0040] Among them, the conduction threshold voltage, the first threshold and the second threshold can all be set independently, and the embodiment of the utility model does not limit this.

[0041] The utility model provides a power supply protection circuit. Considering that the on-off state of PMOS can be changed by controlling the voltage between the gate and the source of PMOS, the utility model uses PMOS as a control switch between a power adapter and a power input interface of an electrical device. The undervoltage protection module 2 can turn on the PMOS by controlling the gate voltage of the PMOS when the output voltage of the power adapter is greater than a first threshold value, and turn off the PMOS by controlling the gate voltage of the PMOS when the output voltage of the power adapter is less than the first threshold value. The overvoltage protection module 3 can turn off the PMOS by controlling the gate voltage of the PMOS when the output voltage of the power adapter is greater than a second threshold value, that is, the PMOS is turned off when the output voltage of the power adapter is outside the range from the first threshold value to the second threshold value, thereby realizing overvoltage and undervoltage protection for the electrical device, and has a simple structure, reduced components, and low cost.

[0042] Based on the above embodiments:

[0043] As an optional embodiment, the undervoltage protection module 2 includes a first recoverable diode, a first current limiting resistor, a first transistor, a first voltage dividing resistor and a second voltage dividing resistor;

[0044] The cathode of the first recoverable diode is respectively connected to the output end of the power adapter, the first end of the first voltage-dividing resistor and the source of PMOS 1, the anode of the first recoverable diode is connected to the first end of the first current-limiting resistor, the second end of the first current-limiting resistor is connected to the base of the first transistor, the second end of the first voltage-dividing resistor is respectively connected to the gate of PMOS1 and the first end of the second voltage-dividing resistor, the second end of the second voltage-dividing resistor is connected to the collector of the first transistor, and the emitter of the first transistor is grounded.

[0045] To better illustrate the embodiments of the present invention, please refer to Figure 2 , Figure 2 A schematic diagram of another power supply protection circuit provided by the utility model. Figure 2 J1 is a power socket for connecting a power adapter, Vin is the voltage input terminal of the power supply protection circuit, VSystem is the power input interface of the power-consuming device, and C2 is the input capacitor of the power-consuming device. For the power supply protection circuit, there are several working states, among which the system is in the normal working state:

[0046] The voltage relationship is: D1 conduction voltage < input voltage Vin < D2 conduction voltage;

[0047] Specifically, the power adapter is inserted into the electrical device through J1, and the input voltage enters the second recoverable diode D2 through the first pull-up resistor R1. Because the input voltage is less than the conduction voltage of D2 (the second threshold), D2 is in the off state, and there is no current flowing through the second current limiting resistor R3 and the base of the second transistor Q3, so Q3 is in the off state. Because the input voltage is greater than the conduction voltage of the first recoverable diode D1 (the first threshold), D1 is turned on, and the voltage across D1 remains unchanged. R5 is the first current limiting resistor to prevent excessive current from burning the first transistor Q2. The input voltage enters the base of Q2 after passing through D1 and R5, and Q2 is turned on. Q2 pulls down the gate of PMOS Q1 to the power ground through the second voltage divider resistor R4. The source of Q1 is connected to the input voltage, and the gate is pulled up to the input voltage through the first voltage divider resistor R2. At this time, the gate and source voltages of Q1 are:

[0048] Vgs = Vin / (R2+R4)*R4;

[0049] When the Vgs voltage is lower than the Q1 conduction threshold voltage, Q1 will enter the conduction state, and the mainboard will be powered on and start working.

[0050] Specifically, the undervoltage protection state of the power supply protection circuit is:

[0051] The voltage relationship is: input voltage Vin<D1 conduction voltage<D2 conduction voltage;

[0052] The power adapter is inserted into the electrical device through J1, and the input voltage enters D2 through the first pull-up resistor R1. Because the input voltage is lower than the on-voltage of D2, D2 is in the off state, no current flows through the base of R3 and Q3, and Q3 is in the off state; the power adapter is inserted into the electrical device through J1. Because the input voltage is lower than the on-voltage of D1, D1 is in the off state, no current flows through the base of R5 and Q2, and Q2 is in the off state.

[0053] The source of Q1 is connected to the input voltage, and the gate is pulled up to the input voltage through R2. Since Q3 and Q2 are both in the cut-off state, no current flows through the gate of Q1. At this time, the gate voltage of Q1 is equal to the source voltage, Vgs=0, and the Vgs voltage is greater than the turn-on threshold voltage of Q1. Q1 is in the cut-off state, and the mainboard of the electrical equipment is not powered.

[0054] Specifically, the specific circuit of the undervoltage protection module 2 in the embodiment of the utility model has the advantages of simple structure and low cost.

[0055] Of course, in addition to this specific structure, the undervoltage protection module 2 can also be of other types, which is not limited in the embodiment of the present utility model.

[0056] As an optional embodiment, the undervoltage protection module 3 further includes a first pull-down resistor;

[0057] The first end of the first pull-down resistor is connected to the second end of the first current limiting resistor and the base of the first transistor respectively, and the second end of the first pull-down resistor is grounded.

[0058] Specifically, the first pull-down resistor is Figure 2 R6 in the circuit can prevent Q2 from malfunctioning due to the influence of noise signals, thus improving the reliability of power supply protection.

[0059] As an optional embodiment, the overvoltage protection module 3 includes a first pull-up resistor, a second recoverable diode, a second current limiting resistor and a second transistor;

[0060] The first end of the first pull-up resistor is respectively connected to the output end of the power adapter, the emitter of the second transistor, the first end of the first voltage-dividing resistor and the source of PMOS 1, the second end of the first pull-up resistor is respectively connected to the cathode of the second recoverable diode and the first end of the second current-limiting resistor, the anode of the second recoverable diode is grounded, the second end of the second current-limiting resistor is connected to the base of the second transistor, and the collector of the second transistor is respectively connected to the second end of the first voltage-dividing resistor and the gate of PMOS 1.

[0061] Specifically, the overvoltage protection state of the power supply protection circuit is:

[0062] The voltage relationship is: D1 conduction voltage < D2 conduction voltage < input voltage Vin;

[0063] The power adapter is inserted into the electrical device through J1, and the input voltage enters the D2 voltage regulator diode through the R1 pull-up resistor. Because the input voltage is greater than the D2 turn-on voltage, D2 is turned on, and the input voltage flows through the Q3 emitter through the base and R3 to the power ground. Q3 is turned on, and the Q1 gate is pulled up to the power supply voltage. At this time, the Q1 gate voltage is equal to the source voltage, Vgs=0, and the Vgs voltage is greater than the Q1 turn-on threshold voltage. Q1 is in the cut-off state, and the mainboard is not powered.

[0064] Specifically, the specific circuit of the overvoltage protection module 3 in the embodiment of the utility model has the advantages of simple structure and low cost.

[0065] Of course, in addition to this specific structure, the overvoltage protection module 3 can also be of other types, which is not limited in the embodiment of the present utility model.

[0066] As an optional embodiment, the first recoverable diode and the second recoverable diode are both zener diodes.

[0067] Specifically, the voltage zener diode has the advantages of small size, low cost and long life.

[0068] Of course, in addition to the voltage regulator diode, the first recoverable diode and the second recoverable diode may also be of other types, such as TVS (Transient Voltage Supperessor), etc., which is not limited in the embodiment of the utility model.

[0069] As an optional embodiment, the power supply protection circuit further includes a circuit substrate;

[0070] The PMOS 1 , the undervoltage protection module 2 and the overvoltage protection module 3 are disposed on a circuit substrate.

[0071] Specifically, the PMOS 1 , the undervoltage protection module 2 , and the overvoltage protection module 3 can be fixed by the circuit substrate, so that the power supply protection circuit is more stable and is conducive to reducing the volume.

[0072] As an optional embodiment, the power supply protection circuit further includes:

[0073] The delay protection circuit is respectively connected to the source of PMOS1, the gate of PMOS1 and the power ground, and is used to control the gate voltage of PMOS1 to drop from the output voltage of the power adapter to a preset voltage division value when connected to the power adapter.

[0074] Specifically, considering that during the hot plugging process of the power supply, the mainboard of the electrical device may be impacted by the surge current, and at the moment of hot plugging, the capacitive load may cause a large current and spark problems, in order to avoid this situation, a delay protection circuit is designed in the embodiment of the utility model, which is respectively connected to the source of PMOS 1, the gate of PMOS 1 and the power ground, and is used to control the voltage of the gate of PMOS 1 from the output voltage of the power adapter to a preset voltage divider value when connected to the power adapter, thereby realizing the slow conduction of PMOS 1, and the impact of surge current on the mainboard of the electrical device is avoided by controlling the slow conduction of PMOS 1.

[0075] As an optional embodiment, the delay protection circuit includes a capacitor;

[0076] A first terminal of the capacitor is connected to the source of the PMOS 1 , and a second terminal of the capacitor is connected to the gate of the PMOS 1 .

[0077] For details, see Figure 2As shown, one end of capacitor C1 is connected to the input voltage, and the other end is connected to the gate of Q1. One end of the second voltage-dividing resistor R4 is connected to C1, and the other end is connected to the power ground through Q2. C1 and R4 form an RC discharge circuit. When the power adapter is inserted into the power-consuming device through J1, the voltage across the capacitor cannot change suddenly. Due to the existence of C1 capacitor, the voltage across the capacitor is equal to the input voltage Vin, that is, the gate and source voltage of Q1 is equal to the input voltage Vg=Vs=Vin, Vgs=0, Vgs voltage is greater than Q1 conduction threshold voltage, Q1 is in the cut-off state, and the mainboard is not powered. Because in normal working state, Q2 is in the on state, the charge stored in capacitor C1 is slowly discharged to the power ground through R4 and Q2. After a period of delay T, Q1 gate voltage Vg also decreases, and Q1 source voltage is always equal to input voltage Vg=Vin. When Vgs voltage is less than Q1 conduction threshold voltage, Q1 will enter the on state, and the mainboard will be powered on and start working.

[0078] To better illustrate the embodiments of the present invention, please refer to Figure 3 , Figure 3 This is a curve diagram of the voltage across a capacitor provided by the present invention. It can be seen that the input voltage Vin (ie, the source voltage of the PMOS 1) remains unchanged, while the gate voltage of the PMOS 1 decreases from the input voltage to a preset voltage-divided value.

[0079] Specifically, capacitors have the advantages of low cost and long life.

[0080] Of course, in addition to capacitors, the delay protection circuit can also be of other types, which is not limited in the embodiments of the present utility model.

[0081] The utility model also provides an electrical device, including an electrical device body, and further comprising:

[0082] A power supply protection circuit as above connected to the main body of the electrical equipment.

[0083] For an introduction to the electrical equipment provided by the embodiment of the utility model, please refer to the aforementioned embodiment of the power supply protection circuit, and the embodiment of the utility model will not be described in detail here.

[0084] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. It should also be noted that in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the element.

[0085] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power supply protection circuit, characterized in that: Applied to electrical equipment, including: A PMOS, a source electrode connected to the output terminal of the power adapter, and a drain electrode connected to the power input interface of the power-consuming device; an undervoltage protection module, connected to the output end of the power adapter, the source of the PMOS, the gate of the PMOS and a power ground respectively, and used to control the gate voltage of the PMOS to be a preset voltage-divided value of the output voltage of the power adapter when the output voltage of the power adapter is greater than a first threshold, and to control the gate voltage of the PMOS to be equal to the source voltage when the output voltage of the power adapter is less than the first threshold; an overvoltage protection module, connected to the output end of the power adapter, the source of the PMOS, the gate of the PMOS and a power ground respectively, and used for controlling the gate voltage of the PMOS to be equal to the source voltage when the output voltage of the power adapter is greater than a second threshold; The second threshold is greater than the first threshold.

2. The power supply protection circuit according to claim 1, characterized in that: The undervoltage protection module includes a first recoverable diode, a first current limiting resistor, a first transistor, a first voltage dividing resistor and a second voltage dividing resistor; The cathode of the first recoverable diode is respectively connected to the output end of the power adapter, the first end of the first voltage-dividing resistor and the source of the PMOS, the anode of the first recoverable diode is connected to the first end of the first current-limiting resistor, the second end of the first current-limiting resistor is connected to the base of the first transistor, the second end of the first voltage-dividing resistor is respectively connected to the gate of the PMOS and the first end of the second voltage-dividing resistor, the second end of the second voltage-dividing resistor is connected to the collector of the first transistor, and the emitter of the first transistor is grounded.

3. The power supply protection circuit according to claim 2, characterized in that: The undervoltage protection module also includes a first pull-down resistor; The first end of the first pull-down resistor is connected to the second end of the first current limiting resistor and the base of the first transistor respectively, and the second end of the first pull-down resistor is grounded.

4. The power supply protection circuit according to claim 2, characterized in that: The overvoltage protection module includes a first pull-up resistor, a second recoverable diode, a second current limiting resistor and a second transistor; The first end of the first pull-up resistor is respectively connected to the output end of the power adapter, the emitter of the second transistor, the first end of the first voltage-dividing resistor and the source of the PMOS, the second end of the first pull-up resistor is respectively connected to the cathode of the second recoverable diode and the first end of the second current-limiting resistor, the anode of the second recoverable diode is grounded, the second end of the second current-limiting resistor is connected to the base of the second transistor, and the collector of the second transistor is respectively connected to the second end of the first voltage-dividing resistor and the gate of the PMOS.

5. The power supply protection circuit according to claim 4, characterized in that: The first recoverable diode and the second recoverable diode are both zener diodes.

6. The power supply protection circuit according to claim 1, characterized in that: The power supply protection circuit also includes a circuit substrate; The PMOS, the undervoltage protection module and the overvoltage protection module are arranged on the circuit substrate.

7. The power supply protection circuit according to any one of claims 1 to 6, characterized in that: The power supply protection circuit also includes: The delay protection circuit is respectively connected to the source of the PMOS, the gate of the PMOS and the power ground, and is used to control the voltage of the gate of the PMOS to drop from the output voltage of the power adapter to the preset voltage division value when connected to the power adapter.

8. The power supply protection circuit according to claim 7, characterized in that: The time delay protection circuit includes a capacitor; The first end of the capacitor is connected to the source of the PMOS, and the second end of the capacitor is connected to the gate of the PMOS.

9. An electrical device, characterized in that: Including the electrical equipment body, also includes: A power supply protection circuit as described in any one of claims 1 to 8 connected to the electrical equipment body.

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