Over-voltage and over-negative protection circuit, over-voltage and over-negative protection device and electronic equipment

Abstract

The utility model discloses an over-voltage and over-negative protection circuit, an over-voltage and over-negative protection device and electronic equipment, and relates to the technical field of power electronics, and the over-voltage and over-negative protection circuit is connected between a thermistor and a controller and is used for protecting the clamping of the input and output ends of the controller according to the detection voltage on a protection detection node. The over-voltage and over-negative protection circuit comprises an over-voltage protection module which is connected between the thermistor and the input and output end of the controller and is used for carrying out over-voltage protection on the clamping of the input and output end when the detection voltage is detected to be over-voltage; and the negative voltage protection module is connected between the thermistor and the input and output end of the controller and is used for carrying out negative voltage protection on the clamping of the input and output end when the detection voltage flowing into the input and output end is detected to be negative voltage, so that the defect that leakage current flows into the input and output end of the controller through the thermistor is overcome; and the main control chip to which the input and output ends belong is damaged.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and in particular to an overvoltage and over-negative protection circuit, an overvoltage and over-negative protection device and electronic equipment. Background Art

[0002] Currently, the resistance value of the thermistor is collected by a controller on the market to read the temperature of the device where the thermistor is located. The operating status of the device is controlled based on the read device temperature to ensure the normal operation of the device.

[0003] The thermistor is directly connected to the conductive metal such as the entire casing of the device. When the conductive metal generates leakage voltage due to insulation or voltage resistance, the leakage current corresponding to the leakage voltage will flow into the input and output terminals through the wires between the thermistor and the input and output terminals of the controller, causing forward overvoltage or reverse negative voltage breakdown problems at the input and output terminals, thereby damaging the main control chip to which the input and output terminals belong, making it impossible for the main control chip to normally control the operation of the equipment, affecting the normal operation of the equipment. Utility Model Content

[0004] The main purpose of the utility model is to provide an overvoltage and over-negative protection circuit, an overvoltage and over-negative protection device and an electronic device, aiming to solve the technical problem that leakage current flows into the input and output terminals of the controller through the thermistor and causes damage to the main control chip to which the input and output terminals belong.

[0005] To achieve the above object, the utility model provides an overvoltage and over-negative protection circuit, which is connected between the thermistor and the controller and is used to clamp the input and output terminals of the controller for protection according to the detection voltage on the protection detection node. The overvoltage and over-negative protection circuit includes:

[0006] An overvoltage protection module is connected between the thermistor and the input and output terminals of the controller, and is used to clamp the input and output terminals for overvoltage protection when the detection voltage is detected to be an overvoltage;

[0007] The negative pressure protection module is connected between the thermistor and the input / output terminal of the controller, and is used to clamp the input / output terminal for negative pressure protection when it is detected that the detection voltage flowing into the input / output terminal is a negative voltage.

[0008] Optionally, the overvoltage protection module includes an overvoltage protection circuit;

[0009] The overvoltage protection circuit is connected between the thermistor and the input and output terminals of the controller, and is used to enter a conducting state when the detection voltage is detected to be an overvoltage, and based on the conducting state, limit the current belonging to the overvoltage from flowing into the input and output terminals.

[0010] Optionally, the overvoltage protection circuit includes: a clamping transistor;

[0011] The emitter of the clamping transistor is connected between the thermistor and the input and output terminals;

[0012] The emitter of the clamping transistor is set as the protection detection node, and when the detection voltage exceeds a preset upper limit detection voltage, the current corresponding to the temperature voltage output by the thermistor is controlled to flow to the collector of the clamping transistor via the emitter of the clamping transistor.

[0013] Optionally, the negative pressure protection module includes a negative pressure protection circuit;

[0014] The negative pressure protection circuit is connected between the thermistor and the input and output terminals of the controller, and is used to enter a conducting state when the detection voltage is detected to be a negative voltage, and based on the conducting state, limit the current belonging to the negative voltage from flowing into the input and output terminals.

[0015] Optionally, the negative pressure protection circuit includes: a clamping diode;

[0016] The cathode of the clamping diode is connected between the thermistor and the input and output terminals;

[0017] The cathode of the clamping diode is set as the protection detection node, and when the detection voltage is lower than a preset lower limit detection voltage, the current corresponding to the temperature voltage output by the thermistor is controlled to flow to the cathode of the clamping diode via the anode of the clamping diode.

[0018] Optionally, the overvoltage and over-negative protection circuit further includes a first-order filtering unit;

[0019] The first-order filtering unit is connected between the thermistor and the input / output end, and is used for filtering the temperature voltage input from the thermistor to the input / output end.

[0020] Optionally, the first-order filtering unit includes a first resistor, a second resistor and a first capacitor;

[0021] The first resistor is connected between the thermistor and the input / output terminal, the first end of the second resistor and the first end of the first capacitor are respectively connected to the connecting line between the thermistor and the first resistor, the second end of the second resistor is connected to the power supply voltage terminal, and the second end of the first capacitor, the positive electrode of the clamping diode and the collector of the clamping transistor are connected to the ground terminal.

[0022] Optionally, the overvoltage and over-negative protection circuit further includes: a third resistor and a second capacitor;

[0023] The first end of the third resistor is connected to the power supply voltage end, the second end of the third resistor is connected to the first end of the second capacitor, the connecting line between the third resistor and the second capacitor is connected to the base of the clamping transistor, and the second end of the second capacitor is connected to the ground end.

[0024] In addition, to achieve the above-mentioned purpose, the utility model also provides an overvoltage and over-negative protection device, including an overvoltage and over-negative protection circuit; the overvoltage and over-negative protection circuit is used to perform protection operations on equipment loaded with the overvoltage and over-negative protection device, and the overvoltage and over-negative protection device is configured as the overvoltage and over-negative protection circuit as described above.

[0025] In addition, to achieve the above-mentioned purpose, the utility model also provides an electronic device, including an overvoltage and over-negative protection device; the overvoltage and over-negative protection device includes an overvoltage and over-negative protection circuit for performing protection operations on the electronic device, and the overvoltage and over-negative protection device is configured as the overvoltage and over-negative protection circuit as described above.

[0026] In the technical solution of the utility model, an overvoltage and over-negative protection circuit connected between the thermistor and the controller is designed. The overvoltage and over-negative protection circuit clamps the input and output terminals of the controller to protect it according to the detection voltage on the protection detection node. Specifically, the overvoltage and over-negative protection circuit includes an overvoltage protection module and a negative voltage protection module, wherein the overvoltage protection module is connected between the thermistor and the input and output terminals of the controller, and is used to clamp the input and output terminals for overvoltage protection when the detection voltage is detected to be an overvoltage; the negative voltage protection module is connected between the thermistor and the input and output terminals of the controller, and is used to clamp the input and output terminals for negative voltage protection when the detection voltage flowing into the input and output terminals is detected to be a negative voltage. Through the overvoltage protection module and the negative voltage protection module, the detection voltage with leakage voltage is prevented from flowing into the input and output terminals, thereby avoiding the breakdown phenomenon caused by the leakage voltage on the input and output terminals, thereby effectively protecting the main control chip to which the input and output terminals belong. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 This is a schematic diagram of a module in which the overvoltage and over-negative protection circuit of the utility model is connected between a thermistor and a controller;

[0029] Figure 2 This is a schematic diagram of a circuit connected between a thermistor and a controller when the overvoltage protection circuit of the utility model is turned on;

[0030] Figure 3 This is a schematic diagram of a circuit connected between a thermistor and a controller when the negative pressure protection circuit of the utility model is turned on;

[0031] Figure 4 The utility model is provided with the over-voltage and over-negative protection circuit proposed by the present invention in the controller to control the load circuit schematic diagram.

[0032] Description of Figure Numbers:

[0033] Label name Label name 10 Overvoltage and over-negative protection circuit Q1 Clamp transistor RNTC Thermistor 1021 Negative pressure protection circuit MCU Controller D1 Clamping diode 101 Overvoltage protection module 103 First order filter unit 102 Negative pressure protection module R1-R5 resistance 1011 Overvoltage protection circuit C1-C2 capacitance

[0034] The realization of the purpose, functional features and advantages of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments 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.

[0036] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0038] Reference Figure 1 As shown, Figure 1The utility model proposes a module schematic diagram of an overvoltage and over-negative protection circuit 10, which is connected between the thermistor RNTC and the controller MCU, and is used to clamp the input and output terminals of the controller MCU according to the detection voltage on the protection detection node to protect the overvoltage and over-negative protection circuit 10. The overvoltage and over-negative protection circuit 10 includes:

[0039] An overvoltage protection module 101 is connected between the thermistor RNTC and the input and output terminals of the controller MCU, and is used to clamp the input and output terminals for overvoltage protection when the detection voltage is detected to be an overvoltage;

[0040] The negative pressure protection module 102 is connected between the thermistor RNTC and the input and output terminals of the controller MCU, and is used to clamp the input and output terminals for negative pressure protection when it is detected that the detection voltage flowing into the input and output terminals is a negative voltage.

[0041] It should be noted that the overvoltage and over-negative protection circuit 10 proposed in this example is arranged on an acquisition module, which is used to collect the temperature voltage on the thermistor RNTC and transmit the temperature voltage to the main control chip of the controller MCU, so that the main control chip can control the operation of the corresponding device based on the conduction level corresponding to the connected temperature voltage output.

[0042] The overvoltage and over-negative protection circuit 10 proposed in this example is set up to protect the main control chip, and is used to prevent the leakage voltage on the temperature voltage transmitted to the main control chip from causing the input and output terminals to be broken down, thereby causing damage to the main control chip.

[0043] The overvoltage generated by the leakage voltage is detected and processed by the overvoltage protection module 101 provided on the overvoltage and over-negative circuit. The detection voltage on the protection detection node is detected in real time by the overvoltage protection module 101. When the detection voltage is detected to be an overvoltage, the overvoltage protection module 101 connects the current corresponding to the temperature voltage where the leakage voltage exists to prevent the current from flowing into the input and output terminals and causing breakdown problems on the input and output terminals.

[0044] The negative voltage generated by the leakage voltage is detected and processed by the negative voltage protection module 102 provided on the overvoltage and over-negative circuit. The detection voltage on the protection detection node is detected in real time by the negative voltage protection module 102. When the detection voltage is detected to be a negative voltage, the negative voltage protection module 102 connects the current corresponding to the temperature voltage where the leakage voltage exists to prevent the current from flowing into the input and output terminals and causing breakdown problems on the input and output terminals.

[0045] The detection voltage is the voltage of the current flowing on the wire of the overvoltage and over-negative protection circuit 10 due to the temperature voltage, and the protection detection node is any node on the wire connected to the input and output terminals of the overvoltage and over-negative protection circuit 10.

[0046] Specifically, refer to Figure 2 As shown, the overvoltage protection module 101 includes an overvoltage protection circuit 1011;

[0047] The overvoltage protection circuit 1011 is connected between the thermistor RNTC and the input and output terminals of the controller MCU, and is used to enter a conduction state when the detection voltage is detected to be an overvoltage. Based on the conduction state, the current corresponding to the temperature voltage with a leakage voltage is connected to limit the current belonging to the overvoltage from flowing into the input and output terminals.

[0048] Further, the overvoltage protection circuit 1011 includes: a clamping transistor Q1;

[0049] The emitter of the clamping transistor Q1 is connected between the thermistor RNTC and the input and output ends; wherein the emitter of the clamping transistor Q1 is set as the protection detection node, and when the detection voltage exceeds a preset upper limit detection voltage, the current corresponding to the temperature voltage output by the thermistor RNTC is controlled to flow to the collector of the clamping transistor Q1 via the emitter of the clamping transistor Q1.

[0050] Reference Figure 2 It can be seen that the clamp transistor Q1 in this example is a PNP junction. Figure 2 When the VCC in the clamp transistor Q1 starts to output the power supply voltage, the clamp transistor Q1 is in the cut-off state. When the detection voltage flowing through the emitter of the clamp transistor Q1 is less than the preset upper limit detection voltage, the current corresponding to the detection voltage will flow normally into the input and output terminals (i.e. Figure 2 PA2 in the circuit provides temperature detection for the main control chip.

[0051] When there is a leakage voltage on the temperature voltage output by the thermistor RNTC, the protection detection node, that is, the detection voltage on the emitter of the clamping transistor Q1 is the temperature voltage + the leakage voltage, and the detection voltage will exceed the preset upper limit detection voltage (that is, the sum of the power supply voltage on the power supply voltage end and the on-voltage of the clamping transistor Q1). At this time, the current on the wire between the thermistor RNTC and the input and output ends will flow directly from the emitter of the clamping transistor Q1 to the collector of the clamping transistor Q1, and will not flow into the input and output ends, thereby avoiding the breakdown problem of the input and output ends caused by overvoltage.

[0052] It should be noted that Figure 2The first resistor R1, the second resistor R2 and the first capacitor C1 form a first-order filter unit 103 for filtering the temperature voltage, and the third resistor R3 and the second capacitor C2 are used to reduce the current on the line and protect the base of the clamp transistor Q1. The second resistor R2 is a pull-up resistor.

[0053] Specifically, refer to Figure 3 As shown, the negative pressure protection module 102 includes a negative pressure protection circuit 1021;

[0054] The negative pressure protection circuit 1021 is connected between the thermistor RNTC and the input and output terminals of the controller MCU, and is used to enter a conduction state when it is detected that the detection voltage is a negative voltage. Based on the conduction state, the current corresponding to the temperature voltage with a leakage voltage is connected to limit the current belonging to the negative voltage from flowing into the input and output terminals.

[0055] Further, the negative pressure protection circuit 1021 includes: a clamping diode D1;

[0056] The cathode of the clamping diode D1 is connected between the thermistor RNTC and the input and output terminals; wherein the cathode of the clamping diode D1 is set as the protection detection node, and when the detection voltage is lower than a preset lower limit detection voltage, the current corresponding to the temperature voltage output by the thermistor RNTC is controlled to flow to the cathode of the clamping diode D1 via the anode of the clamping diode D1.

[0057] Reference Figure 3 It can be seen that at the power supply voltage end (i.e. Figure 3 When the VCC in thermistor RNTC starts to output the power supply voltage, the clamping transistor Q1 is turned off, and the current corresponding to the power supply voltage flows through the third resistor R3 and the second capacitor C2. When there is a leakage voltage on the temperature voltage output by the thermistor RNTC, the protection detection node, that is, the detection voltage on the cathode of the clamping diode D1 is the temperature voltage minus the leakage voltage, that is, the detection voltage will be lower than the preset lower limit detection voltage (that is, the voltage difference between the ground voltage on the ground terminal and the conduction voltage of the clamping diode D1). At this time, the current will flow directly from the anode of the clamping diode D1 to the cathode of the clamping diode D1 through the second capacitor C2, and then flow to the first resistor R1 and the first capacitor C1 through the cathode of the diode, and then flow into the ground terminal, but will not flow into the input and output terminal (that is, Figure 3 In PA2 in FIG, the breakdown problem of the input and output terminals caused by negative voltage is avoided.

[0058] Furthermore, the overvoltage and over-negative protection circuit 10 further includes a first-order filtering unit 103;

[0059] The first-order filtering unit 103 is connected between the thermistor RNTC and the input / output end, and is used to filter the temperature voltage input from the thermistor RNTC to the input / output end, so as to ensure the accuracy of the main control chip in operating the device based on the connected temperature voltage.

[0060] The first-order filtering unit 103 includes a first resistor R1, a second resistor R2 and a first capacitor C1;

[0061] The first resistor R1 is connected between the thermistor RNTC and the input and output ends, the first end of the second resistor R2 and the first end of the first capacitor C1 are respectively connected to the connection line between the thermistor RNTC and the first resistor R1, the second end of the second resistor R2 is connected to the power supply voltage end, and the second end of the first capacitor C1, the positive electrode of the clamping diode D1 and the collector of the clamping transistor Q1 are connected to the ground end.

[0062] Furthermore, the overvoltage and over-negative protection circuit 10 further includes: a third resistor R3 and a second capacitor C2;

[0063] The first end of the third resistor R3 is connected to the power supply voltage end, the second end of the third resistor R3 is connected to the first end of the second capacitor C2, the connecting line between the third resistor R3 and the second capacitor C2 is connected to the base of the clamping transistor Q1, and the second end of the second capacitor C2 is connected to the ground end.

[0064] Example

[0065] by Figure 4 Take this as an example to illustrate.

[0066] (1) When the connector corresponding to thermistor RNTC (i.e. Figures 2 to 4 When there is leakage voltage in the temperature voltage output by CN1 in the circuit, the temperature voltage with leakage voltage is filtered by the first resistor R1, the second resistor R2 and the first capacitor C1, and then transmitted to the cathode of the clamping diode D1, that is, Figure 4 At point 1 in the figure, the power supply voltage terminal outputs the power supply voltage at the same time, and the current corresponding to the power supply voltage flows through the third resistor R3 and the second capacitor C2. Since the clamp transistor Q1 is a PNP junction, the clamp transistor Q1 is in a cut-off state at this time.

[0067] ① When the voltage at point 1 is greater than the sum of the power supply voltage and the on-voltage of the clamp transistor Q1, the current corresponding to the temperature voltage with leakage voltage will be transmitted to the emitter of the clamp transistor Q1, that is, Figure 4 At the two points in the circuit, the current flows into the collector of the clamp transistor Q1 through the two points and then flows into the ground terminal, preventing the current from flowing into the input and output terminals.

[0068] ② When the voltage at point 1 is less than the voltage difference between the ground voltage and the conduction voltage of the clamping diode D1, the clamping diode D1 is turned on, and the current flowing through the second capacitor C2 will flow through the positive electrode of the clamping diode D1 to the negative electrode of the clamping diode D1, forming a loop of the clamping diode D1→the first resistor R1→the first capacitor C1→the ground terminal.

[0069] (2) When there is no leakage voltage in the temperature voltage output by the connector corresponding to the thermistor RNTC, that is, there is no need for overvoltage or over-negative protection, the current corresponding to the temperature voltage directly flows into the input and output terminals, and the main control chip on the controller MCU performs analog-to-digital conversion on the temperature voltage based on the connected current to obtain the ADC value. The main control chip performs data comparison based on the ADC value to obtain the device temperature value of the current device, and then generates the conduction level according to the functional logic.

[0070] ① When the generated conduction level is a high level, the conduction level is output to the switching transistor via the output end of the controller MCU. Because the switching transistor is an NPN junction, the switching transistor enters the conduction state at this time, and the two ends of the relay RYL are connected to the 12V power supply and the ground terminal, and the switch K is attracted, so that the connector of the power supply L and the load are connected, and the load enters the working state.

[0071] ②When the generated conduction level is a low level, the conduction level is output to the switching transistor via the output end of the controller MCU. At this time, the switching transistor enters the cut-off state, and the two ends of the relay RYL fail to connect to the 12V power supply and the ground end. The switch K is disconnected. At this time, the connector of the power supply L and the load is disconnected, and the load enters the shutdown state.

[0072] Need to Figures 2 to 4, wherein CN1 is a connector corresponding to the thermistor, "1" and "2" on CN1 are corresponding connection pins, VCC in the controller MCU is a power access terminal, which is connected to the power voltage on the power voltage terminal VCC, GND in the controller MCU is a ground terminal, which is connected to the ground terminal GND, PA2 in the controller MCU is a voltage input terminal, that is, an input and output terminal, PA4 in the controller MCU is a voltage output terminal, the fourth resistor R4 and the fifth resistor R5 connected in series are used to protect the base of the switch transistor Q2, and the second diode is used to prevent the 12V voltage on the +12V from flowing into the switch transistor In the diode, CN101 is the connector of the AC output end, "1" and "2" in CN101 are corresponding connection pins, CN102 is the connector of the load, "1" and "2" in CN102 are corresponding connection pins, IC1 is the power control chip, which is used to provide the connector of the power voltage end with power supply voltage to output AC power L and AC power N, IC1 has two output voltages of +5V and +12V, wherein IC1 provides 5V power supply voltage to the power voltage end of the controller MCU and the power voltage end connected to the first end of the second resistor R2 / the third resistor R3, and provides 12V voltage to the upper side of the relay RYL.

[0073] The utility model also provides an overvoltage and over-negative protection device, the overvoltage and over-negative protection device includes an overvoltage and over-negative protection circuit; the overvoltage and over-negative protection circuit is used to perform a protection operation on a device loaded with the overvoltage and over-negative protection device, and the structure of the overvoltage and over-negative protection circuit can refer to the above embodiment, and will not be repeated here. As a matter of course, since the overvoltage and over-negative protection device of this embodiment adopts the technical solution of the above overvoltage and over-negative protection circuit, the overvoltage and over-negative protection device has all the beneficial effects of the above overvoltage and over-negative protection circuit.

[0074] The utility model also provides an electronic device, the electronic device includes an overvoltage and over-negative protection device, the overvoltage and over-negative protection device includes an overvoltage and over-negative protection circuit for performing protection operations on the electronic device, the structure of the overvoltage and over-negative protection circuit can refer to the above embodiment, and will not be repeated here. As a matter of course, since the electronic device of this embodiment adopts the technical solution of the overvoltage and over-negative protection circuit, the electronic device has all the beneficial effects of the overvoltage and over-negative protection circuit.

[0075] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0076] The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0077] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the utility model in essence or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, including a number of instructions for a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the utility model.

[0078] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An overvoltage and over-negative protection circuit, characterized in that: The overvoltage and over-negative protection circuit is connected between the thermistor and the controller, and is used to clamp and protect the input and output terminals of the controller according to the detection voltage on the protection detection node. The overvoltage and over-negative protection circuit includes: An overvoltage protection module is connected between the thermistor and the input and output terminals of the controller, and is used to clamp the input and output terminals for overvoltage protection when the detection voltage is detected to be an overvoltage; The negative pressure protection module is connected between the thermistor and the input / output terminal of the controller, and is used to clamp the input / output terminal for negative pressure protection when it is detected that the detection voltage flowing into the input / output terminal is a negative voltage.

2. The overvoltage and over-negative protection circuit according to claim 1, characterized in that: The overvoltage protection module includes an overvoltage protection circuit; The overvoltage protection circuit is connected between the thermistor and the input and output terminals of the controller, and is used to enter a conducting state when the detection voltage is detected to be an overvoltage, and based on the conducting state, limit the current belonging to the overvoltage from flowing into the input and output terminals.

3. The overvoltage and over-negative protection circuit according to claim 2, characterized in that: The overvoltage protection circuit includes: a clamping transistor; The emitter of the clamping transistor is connected between the thermistor and the input and output terminals; The emitter of the clamping transistor is set as the protection detection node, and when the detection voltage exceeds a preset upper limit detection voltage, the current corresponding to the temperature voltage output by the thermistor is controlled to flow to the collector of the clamping transistor via the emitter of the clamping transistor.

4. The overvoltage and over-negative protection circuit according to claim 3, characterized in that: The negative pressure protection module includes a negative pressure protection circuit; The negative pressure protection circuit is connected between the thermistor and the input and output terminals of the controller, and is used to enter a conducting state when the detection voltage is detected to be a negative voltage, and based on the conducting state, limit the current belonging to the negative voltage from flowing into the input and output terminals.

5. The overvoltage and over-negative protection circuit according to claim 4, characterized in that: The negative pressure protection circuit includes: a clamping diode; The cathode of the clamping diode is connected between the thermistor and the input and output terminals; The cathode of the clamping diode is set as the protection detection node, and when the detection voltage is lower than a preset lower limit detection voltage, the current corresponding to the temperature voltage output by the thermistor is controlled to flow to the cathode of the clamping diode via the anode of the clamping diode.

6. The overvoltage and over-negative protection circuit according to claim 5, characterized in that: The overvoltage and over-negative protection circuit also includes a first-order filtering unit; The first-order filtering unit is connected between the thermistor and the input / output end, and is used for filtering the temperature voltage input from the thermistor to the input / output end.

7. The overvoltage and over-negative protection circuit according to claim 6, characterized in that: The first-order filtering unit includes a first resistor, a second resistor and a first capacitor; The first resistor is connected between the thermistor and the input / output terminal, the first end of the second resistor and the first end of the first capacitor are respectively connected to the connecting line between the thermistor and the first resistor, the second end of the second resistor is connected to the power supply voltage terminal, and the second end of the first capacitor, the positive electrode of the clamping diode and the collector of the clamping transistor are connected to the ground terminal.

8. The overvoltage and over-negative protection circuit according to claim 7, characterized in that: The overvoltage and over-negative protection circuit further includes: a third resistor and a second capacitor; The first end of the third resistor is connected to the power supply voltage end, the second end of the third resistor is connected to the first end of the second capacitor, the connecting line between the third resistor and the second capacitor is connected to the base of the clamping transistor, and the second end of the second capacitor is connected to the ground end.

9. An overvoltage and over-negative protection device, characterized in that: The overvoltage and over-negative protection device comprises the overvoltage and over-negative protection circuit as claimed in any one of claims 1 to 8.

10. An electronic device, characterized in that: The electronic device comprises the overvoltage and over-voltage protection device as claimed in claim 9.

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