Over-voltage and under-voltage protection circuit

Abstract

The utility model provides an overvoltage and undervoltage protection circuit. The overvoltage and undervoltage protection circuit comprises a power switch assembly, an overvoltage protection control assembly and an undervoltage protection control assembly, the overvoltage protection control assembly is connected with the power switch assembly and the undervoltage protection control assembly. The under-voltage protection control assembly is connected with the power switch assembly. In an under-voltage protection state, the power switch assembly cuts off a power input signal; in an overvoltage protection state, the power switch assembly cuts off a power input signal; in a normal power supply state, the power switch assembly receives a power input signal and outputs a power output signal. According to the invention, the circuit cost is reduced on the basis of realizing overvoltage and undervoltage protection.

Description

Technical Field

[0001] This application relates to the field of power protection circuits, and in particular to an overvoltage and undervoltage protection circuit. Background Technology

[0002] With the widespread use of electronic products, various electronic products offer power adapters of different specifications. These power adapters mostly have similar-looking interfaces, such as the 5.5mm round power connector, which is used in laptop power adapters, webcam power adapters, network routers, and other devices. However, their voltage standards vary widely, including 5V, 9V, 12V, 18V, and 20V. Because their interface sizes are the same, incorrect plugging and unplugging frequently occurs. This can lead to minor issues like the product malfunctioning, or even serious damage to the product's circuitry, posing safety hazards and causing significant problems for product manufacturers' after-sales service.

[0003] To avoid the above situations, manufacturers that prioritize product quality will add overvoltage and undervoltage protection circuits to their products to prevent the product from entering an incorrect operating mode and burning out the product circuitry when the user connects the wrong power supply.

[0004] However, existing overvoltage and undervoltage protection circuits are usually quite complex and have high product costs. Utility Model Content

[0005] In view of the above problems, this application is made in order to provide an overvoltage and undervoltage protection circuit that overcomes or at least partially solves the above problems.

[0006] This application provides an overvoltage and undervoltage protection circuit, including: a power switch assembly, an overvoltage protection control assembly, and an undervoltage protection control assembly;

[0007] The overvoltage protection control component is connected to both the power switch assembly and the undervoltage protection control component; the undervoltage protection control component is connected to the power switch assembly.

[0008] When in undervoltage protection state, the power input signal is transmitted to the undervoltage protection control component and the power switch component, the control signal of the undervoltage protection control component is transmitted to the power switch component, and the power switch component cuts off the power input signal;

[0009] When in overvoltage protection state, the power input signal is transmitted to the undervoltage protection control component, the overvoltage protection control component and the power switch component. The control signal of the overvoltage protection control component is transmitted to the power switch component through the undervoltage protection control component. The power switch component cuts off the power input signal.

[0010] When under normal power supply, the power input signal is transmitted to the undervoltage protection control component and the power switch component. The control signal of the undervoltage protection control component is transmitted to the power switch component. The power switch component receives the power input signal and outputs a power output signal.

[0011] Furthermore, the power switch assembly includes a MOSFET Q1;

[0012] The undervoltage protection control component is connected to the gate of the MOS transistor Q1;

[0013] The power input signal is transmitted to the source of the MOS transistor Q1;

[0014] When under normal power supply conditions, the drain of the MOSFET Q1 outputs the power supply output signal.

[0015] Furthermore, the undervoltage protection control component includes a transistor Q2;

[0016] The collector of transistor Q2 is connected to one end of resistor R3 and the gate of MOSFET Q1; the other end of resistor R3 is connected to the source of MOSFET Q1 and one end of resistor R2; the other end of resistor R2 is connected to the cathode of Zener diode D2 and one end of resistor R4.

[0017] The base of transistor Q2 is connected to the anode of Zener diode D2; the other end of resistor R4 is connected to ground.

[0018] The emitter of the transistor Q2 is connected to the ground wire.

[0019] Furthermore, the overvoltage protection control component includes transistor Q3;

[0020] The base of transistor Q3 is connected to the positive terminal of Zener diode D3; one end of resistor R5 is connected to one end of resistor R6 and the negative terminal of Zener diode D3; the other end of resistor R6 is connected to ground.

[0021] The collector of transistor Q3 is connected to the base of transistor Q2;

[0022] The emitter of the transistor Q3 is connected to ground.

[0023] Furthermore, it also includes: undervoltage hysteresis control components;

[0024] One end of the undervoltage hysteresis control component is connected to the drain of the MOS transistor Q1;

[0025] The other end of the undervoltage hysteresis control component is connected to the negative terminal of the Zener diode D2.

[0026] Furthermore, the undervoltage hysteresis control component includes: a resistor R1 and a diode D1;

[0027] One end of the resistor R1 is connected to the drain of the MOS transistor Q1; the other end of the resistor R1 is connected to the anode of the diode D1; and the cathode of the diode D1 is connected to the cathode of the Zener diode D2.

[0028] Furthermore, it also includes: an overvoltage hysteresis control component;

[0029] One end of the overvoltage hysteresis control component is connected to the negative terminal of the Zener diode D3;

[0030] The other end of the overvoltage hysteresis control component is connected to the gate of the MOS transistor Q1.

[0031] Furthermore, the overvoltage hysteresis control component includes: resistor R7 and diode D4;

[0032] One end of the resistor R7 is connected to the gate of the MOS transistor Q1; the other end of the resistor R7 is connected to the cathode of the diode D4; and the anode of the diode D4 is connected to the cathode of the Zener diode D3.

[0033] This application has the following advantages:

[0034] In the embodiments of this application, considering that existing overvoltage and undervoltage protection circuits are generally complex and costly, this application provides a solution whereby "the power switch assembly is controlled by the overvoltage protection control assembly and the undervoltage protection control assembly, so that the power switch assembly is only turned on within the available power range." Specifically, the overvoltage protection control assembly is connected to both the power switch assembly and the undervoltage protection control assembly; the undervoltage protection control assembly is connected to the power switch assembly; when in undervoltage protection mode, the power input signal is transmitted to the undervoltage protection control assembly and the power switch assembly, and the control signal of the undervoltage protection control assembly is transmitted to the power switch assembly. The power switch assembly cuts off the power input signal. In overvoltage protection mode, the power input signal is transmitted to the undervoltage protection control assembly, the overvoltage protection control assembly, and the power switch assembly. The control signal from the overvoltage protection control assembly is transmitted to the power switch assembly via the undervoltage protection control assembly, and the power switch assembly cuts off the power input signal. In normal power supply mode, the power input signal is transmitted to the undervoltage protection control assembly and the power switch assembly. The control signal from the undervoltage protection control assembly is transmitted to the power switch assembly, and the power switch assembly receives the power input signal and outputs a power output signal. This application reduces circuit costs while achieving overvoltage and undervoltage protection. Attached Figure Description

[0035] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a structural framework diagram of an overvoltage and undervoltage protection circuit provided in one embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the specific structure of an overvoltage and undervoltage protection circuit provided in an embodiment of this application. Detailed Implementation

[0038] To make the objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0039] The inventors, through analysis of existing technologies, discovered that the fundamental reason for the high complexity and cost of current overvoltage and undervoltage protection circuits lies in their reliance on power management chips. These chips often include advanced functions, with overvoltage and undervoltage protection being merely supplementary features, resulting in higher costs. When the product is simple and doesn't require these advanced functions, the chip's performance and cost are wasted, making the product uncompetitive in the market. Furthermore, these chips have limited operating voltage ranges, and can still be damaged under extreme conditions. Moreover, they generally lack hysteresis control, causing repeated switching when the power supply voltage is near the control point, leading to product malfunctions and failures. While some overvoltage and undervoltage protection circuits use discrete components, these are mostly complex, limiting product cost and size, and limiting their application to specific products (such as switching power supplies), resulting in poor versatility.

[0040] Based on this, this application aims to solve the problem of electronic products malfunctioning and circuit burning caused by the misuse of power adapters, and provides a low-cost, comprehensive and more universal overvoltage and undervoltage protection circuit.

[0041] Reference Figure 1 This illustration shows an overvoltage and undervoltage protection circuit provided in an embodiment of the present application, including: a power switch assembly, an overvoltage protection control assembly, and an undervoltage protection control assembly;

[0042] The overvoltage protection control component is connected to both the power switch assembly and the undervoltage protection control component; the undervoltage protection control component is connected to the power switch assembly.

[0043] When in undervoltage protection state, the power input signal is transmitted to the undervoltage protection control component and the power switch component, the control signal of the undervoltage protection control component is transmitted to the power switch component, and the power switch component cuts off the power input signal;

[0044] When in overvoltage protection state, the power input signal is transmitted to the undervoltage protection control component, the overvoltage protection control component and the power switch component. The control signal of the overvoltage protection control component is transmitted to the power switch component through the undervoltage protection control component. The power switch component cuts off the power input signal.

[0045] When under normal power supply, the power input signal is transmitted to the undervoltage protection control component and the power switch component. The control signal of the undervoltage protection control component is transmitted to the power switch component. The power switch component receives the power input signal and outputs a power output signal.

[0046] In the embodiments of this application, considering that existing overvoltage and undervoltage protection circuits are generally complex and costly, this application provides a solution whereby "the power switch assembly is controlled by the overvoltage protection control assembly and the undervoltage protection control assembly, so that the power switch assembly is only turned on within the available power range." Specifically, the overvoltage protection control assembly is connected to both the power switch assembly and the undervoltage protection control assembly; the undervoltage protection control assembly is connected to the power switch assembly; when in undervoltage protection mode, the power input signal is transmitted to the undervoltage protection control assembly and the power switch assembly, and the control signal of the undervoltage protection control assembly is transmitted to the power switch assembly. The power switch assembly cuts off the power input signal. In overvoltage protection mode, the power input signal is transmitted to the undervoltage protection control assembly, the overvoltage protection control assembly, and the power switch assembly. The control signal from the overvoltage protection control assembly is transmitted to the power switch assembly via the undervoltage protection control assembly, and the power switch assembly cuts off the power input signal. In normal power supply mode, the power input signal is transmitted to the undervoltage protection control assembly and the power switch assembly. The control signal from the undervoltage protection control assembly is transmitted to the power switch assembly, and the power switch assembly receives the power input signal and outputs a power output signal. This application reduces circuit costs while achieving overvoltage and undervoltage protection.

[0047] The following will further describe an overvoltage and undervoltage protection circuit in this exemplary embodiment.

[0048] It should be noted that the undervoltage protection state refers to the input state where the voltage of the power input signal is lower than the usable power range; the overvoltage protection state refers to the input state where the voltage of the power input signal is higher than the usable power range; and the normal power supply state refers to the input state where the voltage of the power input signal is within the usable power range.

[0049] Reference Figure 2 In one embodiment of this application, the power switch assembly includes a MOSFET Q1;

[0050] The undervoltage protection control component is connected to the gate of the MOS transistor Q1;

[0051] The power input signal is transmitted to the source of the MOS transistor Q1;

[0052] When under normal power supply conditions, the drain of the MOSFET Q1 outputs the power supply output signal.

[0053] It should be noted that the power switch assembly can be composed of the MOSFET Q1. Q1 can also be other types of transistors, such as N-type MOSFETs, NPN transistors, PNP transistors, etc.

[0054] In one embodiment of this application, the undervoltage protection control component includes a transistor Q2;

[0055] The collector of transistor Q2 is connected to one end of resistor R3 and the gate of MOSFET Q1; the other end of resistor R3 is connected to the source of MOSFET Q1 and one end of resistor R2; the other end of resistor R2 is connected to the cathode of Zener diode D2 and one end of resistor R4.

[0056] The base of transistor Q2 is connected to the anode of Zener diode D2; the other end of resistor R4 is connected to ground.

[0057] The emitter of the transistor Q2 is connected to the ground wire.

[0058] It should be noted that the undervoltage protection control component may include: transistor Q2, Zener diode D2, resistor R2, resistor R3, and resistor R4; the switching of Q2 is directly controlled by using the conduction current of Zener diode D2 as the control source; Q2 may also be other types of transistors, such as MOSFETs.

[0059] When the voltage is too low, the voltage divided by resistors R2 and R4 is lower than the turn-on voltage of Zener diode D2 and transistor Q2. The base current of transistor Q2 is 0, and transistor Q2 is in the off state. Under the pull-up effect of resistor R3, the gate of MOSFET Q1 is at a high voltage, the gate-gate voltage difference of MOSFET Q1 is 0, and MOSFET Q1 is in the off state. The power supply is not turned on, thus achieving undervoltage protection.

[0060] In one embodiment of this application, the overvoltage protection control component includes a transistor Q3;

[0061] The base of transistor Q3 is connected to the positive terminal of Zener diode D3; one end of resistor R5 is connected to one end of resistor R6 and the negative terminal of Zener diode D3; the other end of resistor R6 is connected to ground.

[0062] The collector of transistor Q3 is connected to the base of transistor Q2;

[0063] The emitter of the transistor Q3 is connected to ground.

[0064] It should be noted that the overvoltage protection control component may include: transistor Q3, Zener diode D3, resistor R5 and resistor R6; Q3 may also be other types of transistors, such as MOSFETs;

[0065] When the voltage is too high, the voltage drop across resistors R5 and R6 is higher than the forward voltage of Zener diode D3 and transistor Q3. Transistor Q3 is in the on state, the base voltage of transistor Q2 is forcibly pulled to 0, the base current of transistor Q2 is 0, and transistor Q2 is in the off state. Under the pull-up effect of resistor R3, the gate of MOSFET Q1 is at a high voltage, the gate-gate voltage difference of MOSFET Q1 is 0, and MOSFET Q1 is in the off state. The power supply is not turned on, thus achieving overvoltage protection.

[0066] When the voltage is moderate, the voltage divided by resistors R2 and R4 is higher than the turn-on voltage of Zener diode D2 and transistor Q2, so transistor Q2 is in the ON state. The gate (G) of MOSFET Q1 is at a low voltage, so MOSFET Q1 is in the ON state, and the power supply is on. Simultaneously, the voltage divided by resistors R5 and R6 is lower than the turn-on voltage of Zener diode D3 and transistor Q3, so transistor Q3 is in the OFF state. Transistor Q3 does not affect the ON state of transistor Q2, thus maintaining the ON state of MOSFET Q1 and achieving normal power supply.

[0067] In one embodiment of this application, it further includes: an undervoltage hysteresis control component;

[0068] One end of the undervoltage hysteresis control component is connected to the drain of the MOS transistor Q1;

[0069] The other end of the undervoltage hysteresis control component is connected to the negative terminal of the Zener diode D2.

[0070] In one embodiment of this application, the undervoltage hysteresis control component includes: a resistor R1 and a diode D1;

[0071] One end of the resistor R1 is connected to the drain of the MOS transistor Q1; the other end of the resistor R1 is connected to the anode of the diode D1; and the cathode of the diode D1 is connected to the cathode of the Zener diode D2.

[0072] It should be noted that the series connection order of resistor R1 and diode D1 can be interchanged.

[0073] In one embodiment of this application, it further includes: an overvoltage hysteresis control component;

[0074] One end of the overvoltage hysteresis control component is connected to the negative terminal of the Zener diode D3;

[0075] The other end of the overvoltage hysteresis control component is connected to the gate of the MOS transistor Q1.

[0076] In one embodiment of this application, the overvoltage hysteresis control component includes: a resistor R7 and a diode D4;

[0077] One end of the resistor R7 is connected to the gate of the MOS transistor Q1; the other end of the resistor R7 is connected to the cathode of the diode D4; and the anode of the diode D4 is connected to the cathode of the Zener diode D3.

[0078] It should be noted that the series connection order of resistor R7 and diode D4 can be interchanged.

[0079] In one specific embodiment of this application, the circuit includes undervoltage protection hysteresis control function and overvoltage protection hysteresis control function. Existing protection circuits typically do not have hysteresis control function, and repeated conduction and semi-conduction states will occur at the protection voltage critical point. However, this application can also implement hysteresis control function to avoid critical problems.

[0080] In a specific implementation, the process of implementing undervoltage protection hysteresis control includes:

[0081] When the supply voltage is too low, MOSFET Q1 is not turned on, POWER OUT is 0, and the undervoltage protection holding voltage is determined solely by the voltage divider between resistors R2 and R4. When the voltage fluctuates above the undervoltage protection holding voltage, MOSFET Q1 turns on. Resistor R1 and diode D1 participate in the voltage divider network of resistors R2 and R4, resulting in a higher voltage division value. This makes it easier for transistor Q2 to turn on, meaning the undervoltage protection trigger voltage becomes lower. This achieves hysteresis control, preventing the power switch from repeatedly starting when the supply voltage is at the undervoltage protection critical point, which could cause product malfunction.

[0082] It should be noted that in an undervoltage protection circuit, the trigger voltage refers to the voltage value when the function is activated. The trigger voltage is the critical voltage at which the switch changes from on to off when the supply voltage changes from high to low. The holding voltage refers to the voltage value at which the function remains active. The holding voltage is the critical voltage at which the switch changes from off to on when the supply voltage changes from low to high. In an undervoltage protection circuit, the trigger voltage should be less than the holding voltage.

[0083] In a specific implementation, the overvoltage protection hysteresis control process includes:

[0084] When the supply voltage is too high, transistor Q2 does not conduct, and the voltage at the N-terminal of diode D4 is higher than that at the P-terminal, so diode D4 is cut off. The overvoltage protection holding voltage is determined only by the voltage division of resistors R5 and R6. When the supply voltage fluctuates below the overvoltage protection holding voltage, transistor Q2 conducts, and the voltage at the collector of transistor Q2 becomes 0V. Diode D4 conducts, and resistors R7 and diode D4 participate in the voltage division network of resistors R5 and R6, making the voltage division value lower. Diodes D3 and Q3 are less likely to conduct, which means that the overvoltage protection trigger voltage becomes higher, realizing hysteresis control. This can prevent the power switch from repeatedly starting when the supply voltage is at the overvoltage protection critical point, which would cause the product to malfunction.

[0085] It should be noted that in overvoltage protection circuits, the trigger voltage refers to the voltage value when the function is started. The trigger voltage is the critical voltage at which the switch changes from on to off when the supply voltage changes from low to high. The holding voltage refers to the voltage value at which the function remains effective. The holding voltage is the critical voltage at which the switch changes from off to on when the supply voltage changes from high to low. In overvoltage protection circuits, the trigger voltage should be greater than the holding voltage.

[0086] As an example, the holding voltage and trigger voltage in a circuit can be calculated using the following formula:

[0087] Undervoltage protection holding voltage calculation: Assume the voltage regulation value of D2 is... The turn-on voltage of the transistor's base and emitter is The undervoltage protection maintains the voltage. The calculation formula is:

[0088]

[0089] Undervoltage protection trigger voltage calculation: Assume the regulated voltage of D2 is... The turn-on voltage of the transistor's base and emitter is The forward voltage of D1 is The undervoltage protection trigger voltage The calculation formula is:

[0090]

[0091] Overvoltage protection holding voltage calculation: Assume the voltage regulation value of D3 is... The turn-on voltage of the transistor's base and emitter is The undervoltage protection maintains the voltage. The calculation formula is:

[0092]

[0093] Overvoltage protection trigger voltage calculation: Assume the regulated voltage of D3 is... The turn-on voltage of the transistor's base and emitter is The on-state voltage of D4 is The undervoltage protection trigger voltage The calculation formula is:

[0094]

[0095] It should be noted that, in the embodiments of this application, the circuit implements both overvoltage and undervoltage protection, as well as hysteresis control capability, making the product operation safer and more stable; the circuit cost is low, the entire circuit can be implemented using only 3 transistors, 4 diodes, and a few resistors, which meets the requirements in terms of both BOM cost and product size control; the circuit has a wide range of applications, and various specifications of components can be selected, making it easy to implement in both low-voltage and high-voltage applications; the circuit is not limited to any particular application scenario, and all electronic products can use this design to implement protection functions.

[0096] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0097] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0098] The above provides a detailed description of an overvoltage and undervoltage protection circuit provided in this application. Specific examples have been used to illustrate the principle and implementation of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this application. At the same time, those skilled in the art will have changes in the specific implementation and application scope based on the idea of ​​this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An overvoltage and undervoltage protection circuit, characterized by comprising: The application relates to a power supply switch assembly, an overvoltage protection control assembly and an undervoltage protection control assembly. The overvoltage protection control assembly is connected with the power supply switch assembly and the undervoltage protection control assembly respectively; the undervoltage protection control assembly is connected with the power supply switch assembly. When in an undervoltage protection state, a power supply input signal is transmitted to the undervoltage protection control assembly and the power supply switch assembly; a control signal of the undervoltage protection control assembly is transmitted to the power supply switch assembly; and the power supply switch assembly cuts off the power supply input signal. When in an overvoltage protection state, a power supply input signal is transmitted to the undervoltage protection control assembly, the overvoltage protection control assembly and the power supply switch assembly; a control signal of the overvoltage protection control assembly is transmitted to the power supply switch assembly through the undervoltage protection control assembly; and the power supply switch assembly cuts off the power supply input signal. When in a normal power supply state, a power supply input signal is transmitted to the undervoltage protection control assembly and the power supply switch assembly; a control signal of the undervoltage protection control assembly is transmitted to the power supply switch assembly; and the power supply switch assembly receives the power supply input signal and outputs a power supply output signal. The power supply switch assembly comprises a MOS tube Q1.

2. The over- and under-voltage protection circuit according to claim 1, characterized in that, The undervoltage protection control assembly is connected with the gate of the MOS tube Q1. The power supply input signal is transmitted to the source of the MOS tube Q1. When in a normal power supply state, the drain of the MOS tube Q1 outputs the power supply output signal. The undervoltage protection control assembly comprises a triode Q2.

3. The over- and under-voltage protection circuit according to claim 2, characterized in that, The collector of the triode Q2 is connected with one end of a resistor R3 and the gate of the MOS tube Q1; the other end of the resistor R3 is connected with the source of the MOS tube Q1 and one end of a resistor R2; the other end of the resistor R2 is connected with the negative electrode of a stabilizing diode D2 and one end of a resistor R4; The base of the triode Q2 is connected with the positive electrode of the stabilizing diode D2; the other end of the resistor R4 is connected with a ground wire; The emitter of the triode Q2 is connected with the ground wire. The overvoltage protection control assembly comprises a triode Q3.

4. The over- and under-voltage protection circuit according to claim 3, characterized in that, The base of the triode Q3 is connected with the positive electrode of a stabilizing diode D3; one end of a resistor R5 is connected with one end of a resistor R6 and the negative electrode of the stabilizing diode D3; the other end of the resistor R6 is connected with a ground wire; The collector of the triode Q3 is connected with the base of the triode Q2; The emitter of the triode Q3 is connected with the ground wire. Further, the application also relates to an undervoltage hysteresis control assembly.

5. The over- and under-voltage protection circuit according to claim 4, characterized in that, One end of the undervoltage hysteresis control assembly is connected with the drain of the MOS tube Q1; The other end of the undervoltage hysteresis control assembly is connected with the negative electrode of the stabilizing diode D2. The undervoltage hysteresis control assembly comprises a resistor R1 and a diode D1. One end of the resistor R1 is connected with the drain of the MOS tube Q1; the other end of the resistor R1 is connected with the positive electrode of the diode D1; the negative electrode of the diode D1 is connected with the negative electrode of the stabilizing diode D2.

6. The overvoltage and undervoltage protection circuit of claim 5, wherein, Further, the application also relates to an overvoltage hysteresis control assembly. One end of the overvoltage hysteresis control assembly is connected with the negative electrode of the stabilizing diode D3; 7. The over- and under-voltage protection circuit of claim 4, wherein, ​ ​ ​ The other end of the overvoltage hysteresis control assembly is connected with the gate of the MOS tube Q1.

8. The overvoltage undervoltage protection circuit of claim 7, wherein, The overvoltage hysteresis control assembly comprises a resistor R7 and a diode D4. One end of the resistor R7 is connected with the gate of the MOS tube Q1, and the other end of the resistor R7 is connected with the negative electrode of the diode D4; the positive electrode of the diode D4 is connected with the negative electrode of the voltage stabilizing diode D3.

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