Over-voltage and under-voltage protection system and over-voltage and under-voltage protection circuit thereof

Abstract

The utility model provides an overvoltage and undervoltage protection system and an overvoltage and undervoltage protection circuit thereof, in the overvoltage and undervoltage protection circuit, a voltage acquisition unit acquires an input voltage and outputs the acquired voltage to a node A; one end of the resistor R3 is connected with the input voltage, and the other end is connected with the node B; one end of the resistor R4 is connected with the node B, and the other end is connected with the node C; the cathode of the diode D1 is connected with the node C, and the anode is connected with an enable signal; the first end of the switch tube Q1 is connected with the node B through a resistor R5, the second end is grounded, and the control end is connected with the node D through a resistor R6; the first end of the switch tube Q2 is connected with the node C, the second end is grounded, and the control end is connected with the first end of the switch tube Q1; the positive electrode of the voltage-regulator tube D2 is connected with the node D, and the negative electrode is connected with the second end of the comparator; the first end of the comparator is connected with the node A, and the third end is grounded. Compared with the prior art, the circuit is low in cost, quick in response, high in precision, small in temperature drift, and capable of accurately and quickly protecting electronic functional elements.

Description

[Technical field]

[0001] The utility model relates to the technical field of circuit design, in particular to a low-temperature drift over-voltage and under-voltage protection system and an over-voltage and under-voltage protection circuit thereof. [Background technology]

[0002] Over-voltage and under-voltage protection circuits are of great significance in the electronics industry. They can ensure that electronic equipment operates within a safe voltage range and improve the reliability and life of the equipment. Products must have over-voltage and under-voltage protection at different ambient temperatures, and the over-voltage and under-voltage protection points must have high accuracy and should not drift significantly with temperature.

[0003] Therefore, it is necessary to propose a low temperature drift over-voltage and under-voltage protection system and an over-voltage and under-voltage protection circuit thereof. [Contents of the utility model]

[0004] One of the purposes of the utility model is to provide a low-temperature drift over-voltage and under-voltage protection system and an over-voltage and under-voltage protection circuit thereof, wherein the over-voltage and under-voltage protection circuit does not require an external power supply and is constructed by discrete components, has low cost, fast response, high precision, and small temperature drift, and can accurately and quickly protect products at different ambient temperatures.

[0005] According to one aspect of the utility model, the utility model provides an over-voltage and under-voltage protection circuit, which includes a voltage acquisition unit, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a comparator, a diode D1, a voltage stabilizing diode D2, a switch tube Q1 and a switch tube Q2, wherein the voltage acquisition unit acquires an input voltage Vin and outputs the acquired voltage to a node A; one end of the resistor R3 is connected to the input voltage Vin, and the other end thereof is connected to a node B; one end of the resistor R4 is connected to the node B, and the other end thereof is connected to a node C; the cathode of the diode D1 is connected to the node C, and the anode of the diode D1 is connected to the node C, and the cathode ... The first connection end of the switch tube Q1 is connected to the node B via the resistor R5, the second connection end thereof is grounded, and the control end thereof is connected to the node D via the resistor R6; the first connection end of the switch tube Q2 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the first connection end of the switch tube Q1; the anode of the voltage stabilizing diode D2 is connected to the node D, and the cathode thereof is connected to the second connection end of the comparator; the first connection end of the comparator is connected to the node A, and the third connection end thereof is grounded.

[0006] Furthermore, the voltage collection unit includes a resistor R1 and a resistor R2 connected in series between the input voltage Vin and the ground terminal; the connection node between the resistor R1 and the resistor R2 is the node A; the voltage of the node A is the collection voltage output by the voltage collection unit.

[0007] Furthermore, the over-voltage and under-voltage protection circuit also includes a diode D3, a resistor R7 and a resistor R8, the anode of the diode D3 is connected to the node D, and the cathode thereof is grounded via the resistor R7; the second connection end of the switch tube Q1 is grounded via the resistor R8.

[0008] Further, when the input voltage Vin is greater than the set overvoltage protection value, the voltage of the node A is greater than the reference voltage integrated in the comparator, the comparator works, and the comparator pulls down the voltage of its second connection terminal to a predetermined voltage value. At this time, the voltage stabilizing diode D2 does not work, the diode D3 is cut off, the switch tube Q1 is turned off, the switch tube Q2 is turned on, the diode D1 is turned on, and the enable signal EN is pulled from a high level to a low level; when the input voltage Vin is less than the set undervoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator, and the comparator does not work. At this time, the stabilizing diode D2 The voltage-stabilizing diode D2 does not work, the diode D3 is cut off, the switch tube Q1 is turned off, the switch tube Q2 is turned on, and the diode D1 is turned on, and the enable signal EN is pulled from a high level to a low level; when the input voltage Vin is less than the set overvoltage protection value and greater than the set undervoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator, and the comparator does not work. At this time, the voltage-stabilizing diode D2 works, the diode D3 is cut off, the switch tube Q1 is turned on, and the switch tube Q2 is turned off, the voltage of the node C is greater than the voltage of the enable signal EN, the diode D1 is cut off, and the enable signal EN maintains a high level.

[0009] Furthermore, the switch tube Q1 is an NPN type transistor, and the first connection end, the second connection end and the control end of the switch tube Q1 are respectively the collector, the emitter and the base of the NPN type transistor; the switch tube Q2 is an NPN type transistor, and the first connection end, the second connection end and the control end of the switch tube Q2 are respectively the collector, the emitter and the base of the NPN type transistor.

[0010] Furthermore, the selection of the voltage regulator D1 satisfies that the voltage regulation value is equal to the undervoltage protection value; the selection of the resistor R1 and the resistor R2 satisfies that: when the input voltage Vin is greater than the set overvoltage protection value, the voltage of the node A is greater than the reference voltage integrated in the comparator; when the input voltage Vin is less than the set overvoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator.

[0011] Furthermore, the comparator is a controllable precision voltage-stabilizing source; the first connection terminal, the second connection terminal and the third connection terminal of the comparator are respectively the reference electrode, the cathode and the anode of the controllable precision voltage-stabilizing source.

[0012] Furthermore, the temperature drift characteristic of the diode D3 is consistent with the temperature drift characteristic of the switch tube Q1.

[0013] According to another aspect of the utility model, the utility model provides an over-voltage and under-voltage protection system, which includes: an electronic functional element; an enable signal, which is provided to the electronic functional element, and the enable signal is used to drive the electronic functional element; as described in the over-voltage and under-voltage protection circuit of the utility model, its input voltage is the input voltage Vin of the electronic functional element, and its output end is connected to the enable signal.

[0014] Furthermore, when the enable signal is at a high level, the electronic functional element is driven to work; when the enable signal is at a low level, the electronic functional element is stopped from working.

[0015] Compared with the prior art, the over-voltage and under-voltage protection circuit provided by the utility model does not require an external power supply, and is constructed by discrete components. When the input voltage is detected to be higher than the over-voltage protection value or lower than the under-voltage protection value, the over-voltage and under-voltage protection circuit will pull down the enable signal of the driving electronic functional element, thereby immediately shutting down the electronic functional element (or making the electronic functional element stop working) to protect the electronic functional element (or product). The utility model has low cost, fast response, high precision, and small temperature drift, and can accurately and quickly protect electronic functional elements (or products) under different ambient temperatures.

Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0017] Figure 1 A circuit diagram of an over-voltage and under-voltage protection system in one embodiment of the utility model;

[0018] Figure 2 In one embodiment of the present invention, Figure 1 The circuit diagram of the over-voltage and under-voltage protection circuit is shown. [Specific implementation method]

[0019] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0020] The "one embodiment" or "embodiment" referred to herein refers to specific features, structures or characteristics that may be included in at least one implementation of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments. Unless otherwise specified, the words "coupled", "connected", "connected" and "connected" in this document that indicate electrical connection all mean direct or indirect connection. For example, A is connected to B, which includes both direct electrical connection between A and B and A is connected to B through electrical components or circuits. In the present utility model, "greater than" means greater than, and "less than or equal to" means less than or equal to.

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "front", "back", "left", "right", "vertical", "perpendicular", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0022] Please refer to Figure 1 As shown, it is a circuit diagram of an over-voltage and under-voltage protection system in one embodiment of the utility model. Figure 1 The over-voltage and under-voltage protection system shown includes an enable signal EN, an electronic functional element 110 and an over-voltage and under-voltage protection circuit 120 .

[0023] The enable signal EN is provided to the electronic functional element 110, and the enable signal EN is used to drive the electronic functional element 110. In one embodiment, when the enable signal EN is at a high level, the electronic functional element 110 is driven to work; when the enable signal EN is at a low level, the electronic functional element 110 stops working.

[0024] The input voltage Vin (which may also be referred to as the detected voltage) of the over-voltage and under-voltage protection circuit 120 is the input voltage Vin of the electronic functional element 110, and its output terminal Vout is connected to the enable signal EN. When it is detected that the input voltage Vin is higher than the overvoltage protection value or lower than the undervoltage protection value, the over-voltage and under-voltage protection circuit 120 immediately pulls down the enable signal EN, thereby stopping the electronic functional element 110 from working and realizing the over-voltage and under-voltage protection function.

[0025] Please refer to Figure 2 As shown, the utility model is in one embodiment as Figure 1 The circuit diagram of the over-voltage and under-voltage protection circuit is shown. Figure 2The over-voltage and under-voltage protection circuit shown includes a voltage acquisition unit 210 , a resistor R3 , a resistor R4 , a resistor R5 , a resistor R6 , a comparator 220 , a diode D1 , a voltage stabilizing diode D2 , a switch tube Q1 , and a switch tube Q2 .

[0026] Among them, the voltage acquisition unit 210 is used to collect the input voltage Vin and output the collected voltage to the node A; one end of the resistor R3 is connected to the input voltage Vin, and the other end thereof is connected to the node B; one end of the resistor R4 is connected to the node B, and the other end thereof is connected to the node C; the cathode of the diode D1 is connected to the node C, and the anode thereof is connected to the enable signal EN as the output end Vout of the over-voltage and under-voltage protection circuit; the first connection end of the switch tube Q1 is connected to the node B via the resistor R5, the second connection end thereof is grounded, and the control end thereof is connected to the node D via the resistor R6; the first connection end of the switch tube Q2 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the first connection end of the switch tube Q1; the anode of the voltage stabilizing diode D2 is connected to the node D, and the cathode thereof is connected to the second connection end (or the second pin) 2 of the comparator 220; the first connection end (or the first pin) 1 of the comparator 220 is connected to the node A, and the third connection end (or the third pin) 3 thereof is grounded.

[0027] exist Figure 2 In the specific embodiment shown, the voltage acquisition unit 210 includes a resistor R1 and a resistor R2 connected in series between the input voltage Vin and the ground terminal. The connection node between the resistor R1 and the resistor R2 is a node A, and the voltage of the node A is the collection voltage output by the voltage acquisition unit 210.

[0028] Figure 2 The over-voltage and under-voltage protection circuit shown also includes a diode D3, a resistor R7 and a resistor R8, wherein the anode of the diode D3 is connected to the node D, and the cathode thereof is grounded via the resistor R7; the second connection end of the switch tube Q1 is grounded via the resistor R8.

[0029] exist Figure 2 In the specific embodiment shown, the switch tube Q1 is an NPN (i.e., Negative-Positive-Negative) type transistor, and the first connection end, the second connection end, and the control end of the switch tube Q1 are respectively the collector, the emitter, and the base of the NPN type transistor; the switch tube Q2 is an NPN type transistor, and the first connection end, the second connection end, and the control end of the switch tube Q1 are respectively the collector, the emitter, and the base of the NPN type transistor.

[0030] exist Figure 2In the specific embodiment shown, the comparator 220 is a controllable precision voltage regulator TL431 (1-OUTPUT THREETERM VOLTAGE REFERENCE), and the first connection terminal 1, the second connection terminal 2 and the third connection terminal 3 of the comparator 220 are respectively the reference electrode, the cathode and the anode of the controllable precision voltage regulator TL431. Figure 2 The controllable precision voltage regulator TL431 shown can be equivalent to a voltage regulator diode.

[0031] exist Figure 2 In the embodiment shown, the voltage regulator D2 plays the role of setting the undervoltage protection value, and the selection of the voltage regulator D2 needs to satisfy that the voltage regulation value (or working voltage) is equal to the required undervoltage protection value (or the set undervoltage protection value). The selection of the resistor R1 and the resistor R2 needs to satisfy: when the input voltage Vin is greater than the set overvoltage protection value, the voltage of the node A is greater than the reference voltage integrated in the comparator 220 (for example, the reference voltage is 2.5V); when the input voltage Vin is less than the set overvoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator 220.

[0032] The following is a detailed introduction Figure 1 and Figure 2 The working principle of the undervoltage protection system and its over- and undervoltage protection circuit are shown.

[0033] When the input voltage Vin is greater than the set overvoltage protection value, the voltage of node A is greater than the reference voltage integrated in the comparator 220 (i.e., the input voltage of the first pin 1 is higher than the reference voltage integrated in the comparator 220), and the comparator 220 works (i.e., the controllable precision voltage regulator TL431 is internally turned on), and the comparator 220 will pull down the voltage of its second connection terminal 2 to a predetermined voltage value (e.g., 1V). At this time, the voltage regulator diode D2 cannot be broken down, and the voltage regulator diode D2 does not work. Therefore, the diode D3 is cut off and the transistor Q1 is turned off. Because the base of the transistor Q2 is connected to its collector, the transistor Q2 will be turned on in the saturation region, and the enable signal EN will pass through the diode D1 and then through the transistor Q2 directly to the ground, pulling down the enable signal EN, and finally stopping the electronic functional element 110 from working to achieve overvoltage protection. That is to say, when the input voltage Vin is greater than the set overvoltage protection value, the voltage of node A is greater than the reference voltage integrated in the comparator 220, and the comparator 220 works. The comparator 220 pulls down the voltage of its second connection terminal 2 to a predetermined voltage value. At this time, the voltage regulator diode D2 does not work, the diode D3 is cut off, the switch tube Q1 is turned off, the switch tube Q2 is turned on, the diode D1 is turned on, and the enable signal EN is pulled from a high level to a low level.

[0034] When the input voltage Vin is less than the set undervoltage protection value, the voltage of node A is less than the reference voltage integrated in the comparator 220 (i.e., the input voltage of the first pin 1 is lower than the reference voltage integrated in the comparator 220), the comparator 220 does not work (i.e., the controllable precision voltage regulator TL431 cannot be turned on), and the voltage of the second connection terminal 2 of the comparator 220 will not be pulled down. At this time, the voltage regulator diode D2 cannot be broken down, and the voltage regulator diode D2 does not work. Therefore, the diode D3 is cut off and the transistor Q1 is turned off. Because the base of the transistor Q2 is connected to its collector, the transistor Q2 will be turned on in the saturation region, and the enable signal EN will pass through the diode D1 and then through the transistor Q2 directly to the ground, pulling the enable signal EN low, and finally stopping the electronic functional element 110 from working to achieve overvoltage protection. That is to say, when the input voltage Vin is less than the set under-voltage protection value, the voltage of node A is less than the reference voltage integrated in the comparator 220, and the comparator 220 does not work. At this time, the voltage regulator diode D2 does not work, the diode D3 is cut off, the switch tube Q1 is turned off, the switch tube Q2 is turned on, the diode D1 is turned on, and the enable signal EN is pulled from a high level to a low level.

[0035] When the input voltage Vin is less than the set overvoltage protection value and greater than the set undervoltage protection value (that is, when the input voltage Vin is at the normal working voltage), the voltage of node A is less than the reference voltage integrated in the comparator 220 (that is, the input voltage of the first pin 1 is lower than the reference voltage integrated in the comparator 220), and the comparator 220 does not work (that is, the controllable precision voltage regulator TL431 cannot be turned on), and the voltage of the second connection terminal 2 of the comparator 220 will not be pulled down. At this time, the Zener diode D2 is broken down and the Zener diode D2 works. Therefore, the diode D3 is turned on, the transistor Q1 will be turned on in the saturation region, and the collector voltage of the transistor Q1 will be pulled down. Since the base of transistor Q2 and the collector of transistor Q1 are connected together, transistor Q2 will be in the cut-off region and cannot be turned on; because the voltage value of the input voltage Vin after passing through the resistor R3 is higher than the voltage value of the high level of the enable signal EN, the diode D1 is cut off, so the voltage of the enable signal EN will not be pulled down from the high level to the low level; due to the isolation effect of the diode D1, the input voltage Vin will not affect the voltage of the enable signal EN, the enable signal EN maintains a high level, and the electronic functional element 110 will also maintain operation. In other words, when the input voltage Vin is less than the set overvoltage protection value and greater than the set undervoltage protection value, the voltage of node A is less than the reference voltage integrated in the comparator, and the comparator does not work. At this time, the voltage stabilizing diode D2 works, the diode D3 is cut off, the switch tube Q1 is turned on, and the switch tube Q2 is turned off. The voltage of node C is greater than the voltage of the enable signal EN, the diode D1 is cut off, and the enable signal EN maintains a high level.

[0036] It should be noted that Figure 2The low temperature drift characteristic of the overvoltage protection value in the overvoltage and undervoltage protection circuit shown is mainly derived from the low temperature drift of the controllable precision voltage regulator TL431. The reference voltage integrated in the comparator 220 is little affected by temperature. The low temperature drift characteristic of undervoltage is due to Figure 2 In the over- and under-voltage protection circuit shown, diode D3 is selected to suppress the temperature drift characteristics of transistor Q1. The temperature drift characteristics of diode D3 are similar (or consistent) with those of transistor Q1. The anode (or positive pole) of diode D3 is connected to the base of transistor Q1 through resistor R6, and is connected to ground through resistor R7. At high temperatures, the turn-on voltage required for the base of transistor Q1 will also decrease. Since the forward conduction voltage drop of diode D3 will also be affected by high temperature and decrease, the base voltage of transistor Q1 will decrease; when the temperature decreases, the turn-on voltage required for the base of transistor Q1 increases, and the forward conduction voltage drop of diode D3 increases at low temperatures, thereby increasing the base voltage of transistor Q1. Therefore Figure 2 The overvoltage protection value and undervoltage protection value of the overvoltage and undervoltage protection circuit shown are almost unaffected by the ambient temperature.

[0037] In summary, the over-voltage and under-voltage protection circuit provided by the utility model does not require an external power supply, and is constructed by discrete components. When the input voltage is detected to be higher than the over-voltage protection value or lower than the under-voltage protection value, the over-voltage and under-voltage protection circuit will pull down the enable signal of the driving electronic functional element, thereby immediately shutting down the electronic functional element (or making the electronic functional element stop working) to protect the electronic functional element (or product). The utility model has low cost, fast response, high precision, and small temperature drift, and can accurately and quickly protect electronic functional elements (or products) under different ambient temperatures.

[0038] It should be noted that any changes made by those skilled in the art to the specific implementation of the present invention do not deviate from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the aforementioned specific implementation.

Claims

1. An over-voltage and under-voltage protection circuit, characterized in that: It includes a voltage acquisition unit, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a comparator, a diode D1, a voltage regulator diode D2, a switch tube Q1 and a switch tube Q2. The voltage acquisition unit acquires input voltage Vin and outputs the acquired voltage to node A; one end of the resistor R3 is connected to the input voltage Vin, and the other end thereof is connected to node B; one end of the resistor R4 is connected to node B, and the other end thereof is connected to node C; the cathode of the diode D1 is connected to node C, and the anode thereof is connected to the enable signal EN as the output end of the over-voltage and under-voltage protection circuit; the first connection end of the switch tube Q1 is connected to the node B via the resistor R5, the second connection end thereof is grounded, and the control end thereof is connected to node D via the resistor R6; the first connection end of the switch tube Q2 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the first connection end of the switch tube Q1; the anode of the voltage stabilizing diode D2 is connected to the node D, and the cathode thereof is connected to the second connection end of the comparator; the first connection end of the comparator is connected to the node A, and the third connection end thereof is grounded.

2. The over-voltage and under-voltage protection circuit according to claim 1, characterized in that: The voltage acquisition unit includes a resistor R1 and a resistor R2 connected in series between the input voltage Vin and the ground terminal; The connection node between the resistor R1 and the resistor R2 is the node A; The voltage of the node A is the collected voltage output by the voltage collection unit.

3. The over-voltage and under-voltage protection circuit according to claim 2, characterized in that: It also includes a diode D3, a resistor R7 and a resistor R8, The anode of the diode D3 is connected to the node D, and the cathode of the diode D3 is grounded via the resistor R7; The second connection end of the switch tube Q1 is grounded via the resistor R8.

4. The over-voltage and under-voltage protection circuit according to claim 1, characterized in that: When the input voltage Vin is greater than the set overvoltage protection value, the voltage of the node A is greater than the reference voltage integrated in the comparator, the comparator works, and the comparator pulls down the voltage of its second connection terminal to a predetermined voltage value. At this time, the voltage stabilizing diode D2 does not work, the diode D3 is turned off, the switch tube Q1 is turned off, the switch tube Q2 is turned on, the diode D1 is turned on, and the enable signal EN is pulled from a high level to a low level; When the input voltage Vin is less than the set undervoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator, and the comparator does not work. At this time, the voltage regulator diode D2 does not work, the diode D3 is turned off, the switch tube Q1 is turned off, the switch tube Q2 is turned on, the diode D1 is turned on, and the enable signal EN is pulled from a high level to a low level; When the input voltage Vin is less than the set overvoltage protection value and greater than the set undervoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator, and the comparator does not work. At this time, the voltage regulator diode D2 works, the diode D3 is cut off, the switch tube Q1 is turned on, and the switch tube Q2 is turned off. The voltage of the node C is greater than the voltage of the enable signal EN, the diode D1 is cut off, and the enable signal EN maintains a high level.

5. The over-voltage and under-voltage protection circuit according to claim 4, characterized in that: The switch tube Q1 is an NPN type triode, and the first connection end, the second connection end and the control end of the switch tube Q1 are respectively the collector, the emitter and the base of the NPN type triode; The switch tube Q2 is an NPN type triode, and the first connection end, the second connection end and the control end of the switch tube Q2 are respectively the collector, the emitter and the base of the NPN type triode.

6. The over-voltage and under-voltage protection circuit according to claim 5, characterized in that: The selection of the voltage stabilizing diode D2 satisfies that the voltage stabilizing value is equal to the undervoltage protection value; The selection of the resistor R1 and the resistor R2 satisfies: when the input voltage Vin is greater than the set overvoltage protection value, the voltage of the node A is greater than the reference voltage integrated in the comparator; when the input voltage Vin is less than the set overvoltage protection value, the voltage of the node A is less than the reference voltage integrated in the comparator.

7. The over-voltage and under-voltage protection circuit according to claim 3, characterized in that: The comparator is a controllable precision voltage source; The first connection terminal, the second connection terminal and the third connection terminal of the comparator are respectively the reference electrode, the cathode and the anode of the controllable precision voltage-stabilizing source.

8. The over-voltage and under-voltage protection circuit according to claim 7, characterized in that: The temperature drift characteristic of the diode D3 is consistent with the temperature drift characteristic of the switch tube Q1.

9. An over-voltage and under-voltage protection system, characterized in that: It includes: Electronic functional components; an enable signal, which is provided to the electronic functional element, the enable signal is used to drive the electronic functional element; The over-voltage and under-voltage protection circuit according to any one of claims 1 to 8, wherein the input voltage is the input voltage Vin of the electronic functional element, and the output end is connected to the enable signal.

10. The over-voltage and under-voltage protection system according to claim 9, characterized in that: When the enable signal is at a high level, the electronic functional element is driven to operate; When the enable signal is at a low level, the electronic functional element stops working.

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