Over-temperature and overvoltage protection circuit

Abstract

The utility model relates to the technical field of circuit protection, and discloses an over-temperature and over-voltage protection circuit, which is connected between a power supply end and a load end and comprises a first switch element and a temperature sensitive element, wherein the input end of the first switch element is connected with the power supply end, the output end of the first switch element is connected with the load end, and the control end of the first switch element is connected with the output end of the temperature sensitive element; the input end of the temperature sensitive element is connected with the power supply end, and the output end of the temperature sensitive element is connected to the control end of the first switch element. The over-temperature and over-voltage protection circuit has the advantages of being low in cost, simple in circuit and easy to implement, the purpose of over-temperature and over-voltage protection can be achieved, and the reliability, the safety and the operation efficiency of a whole circuit system can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection, in particular to an over-temperature and over-voltage protection circuit. Background Art

[0002] The power supply terminal refers to the part that provides energy for the circuit. Its main responsibility is to provide stable voltage and current to ensure that the load terminal in the circuit can work properly. The load terminal refers to the part that consumes the energy provided by the power supply terminal. Its main responsibility is to use the energy provided by the power supply terminal to perform specific functions.

[0003] Currently, in practical applications, the load terminal faces two significant challenges: one is the overheating phenomenon caused by excessive current beyond the preset range, which may not only reduce the device performance but also pose a threat to the system stability; the other is the abnormal increase in voltage (i.e., over-voltage state), which is extremely likely to damage the sensitive components inside the circuit and even cause the failure or paralysis of the entire system.

[0004] Therefore, it is necessary to improve the existing technology to fundamentally solve the overheating problem caused by excessive current at the load terminal and the risk of component damage caused by excessive voltage, thereby enhancing the reliability, safety, and operating efficiency of the entire circuit system.

[0005] The above information is given as background information only to assist in understanding the present disclosure, and it is not determined or admitted whether any of the above content can be used as the prior art relative to the present disclosure. Summary of the Utility Model

[0006] The utility model provides an over-temperature and over-voltage protection circuit, which fundamentally solves the overheating problem caused by excessive current at the load terminal and the risk of component damage caused by excessive voltage, thereby enhancing the reliability, safety, and operating efficiency of the entire circuit system.

[0007] To achieve the above object, the utility model provides the following technical solutions:

[0008] An over-temperature and over-voltage protection circuit is connected between the power supply terminal and the load terminal, and includes a first switching element and a temperature-sensitive element; wherein,

[0009] The input end of the first switching element is connected to the power supply terminal, the output end of the first switching element is connected to the load terminal, and the control end of the first switching element is connected to the output end of the temperature-sensitive element;

[0010] The input end of the temperature-sensitive element is connected to the power supply terminal, and the output end of the temperature-sensitive element is connected to the control end of the first switching element.

[0011] Further, in the over-temperature and over-voltage protection circuit, the first switching element is the first MOS transistor Q1, and the temperature-sensitive element is the triode Q2;

[0012] The source of the first MOS transistor Q1 is connected to the power supply terminal, the drain of the first MOS transistor Q1 is connected to the load terminal, and the gate of the first MOS transistor Q1 is connected to the collector of the triode Q2;

[0013] The emitter and base of the triode Q2 are respectively connected to the power supply terminal, and the collector of the triode Q2 is connected to GND.

[0014] Further, the over-temperature and over-voltage protection circuit further includes a resistor network;

[0015] The resistor network is connected to the first switching element.

[0016] Further, in the over-temperature and over-voltage protection circuit, the resistor network includes a second resistor R2, a third resistor R3, and a fourth resistor R4;

[0017] The base of the triode Q2 is connected to the power supply terminal through the third resistor R3, and the collector of the triode Q2 is connected to GND through the second resistor R2;

[0018] The fourth resistor R4 is connected between the base of the triode Q2 and GND.

[0019] Further, the over-temperature and over-voltage protection circuit further includes a first resistor R1;

[0020] The gate of the first MOS transistor Q1 is connected to the collector of the triode Q2 through the first resistor R1.

[0021] Further, the over-temperature and over-voltage protection circuit further includes a first capacitor C1;

[0022] The first capacitor C1 is connected between the source and gate of the first MOS transistor Q1.

[0023] Further, the over-temperature and over-voltage protection circuit further includes a second switching element;

[0024] The input terminal of the second switching element is connected to GND, the output terminal of the second switching element is connected to the base of the triode Q2, and the control terminal of the second switching element is connected to the processor.

[0025] Further, in the over-temperature and over-voltage protection circuit, the second switching element is the second MOS transistor Q3;

[0026] The gate of the second MOS transistor Q3 is connected to the processor, the drain of the second MOS transistor Q3 is connected to the base of the transistor Q2, and the source of the second MOS transistor Q3 is connected to GND.

[0027] Further, the over-temperature and over-voltage protection circuit further includes a sixth resistor R6;

[0028] The gate of the second MOS transistor Q3 is connected to the processor through the sixth resistor R6.

[0029] Further, the over-temperature and over-voltage protection circuit further includes a fifth resistor R5;

[0030] The fifth resistor R5 is connected between the gate of the second MOS transistor Q3 and GND.

[0031] Compared with the prior art, the present utility model has the following beneficial effects:

[0032] An over-temperature and over-voltage protection circuit provided by the present utility model is built by several discrete devices, and has the advantages of low cost, simple circuit and easy implementation. By utilizing the temperature characteristics of the temperature-sensitive element and cooperating with the voltage division of the temperature-sensitive element, the on-off control of the first switching element can be realized, so as to realize the on-off control of the power supply path, achieve the purpose of over-temperature and over-voltage protection, and improve the reliability, safety and operation efficiency of the entire circuit system.

[0033] The present utility model has other characteristics and advantages, which will be obvious from the accompanying drawings incorporated herein and the subsequent specific embodiments, or will be described in detail in the accompanying drawings incorporated herein and the subsequent specific embodiments. These accompanying drawings and specific embodiments are used together to explain the specific principles of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 is one of the circuit principle schematic diagrams of an over-temperature and over-voltage protection circuit provided by an embodiment of the present utility model;

[0036] Figure 2 is a schematic diagram of the Vbe-Ic current curve in the transistor specification mentioned in the embodiment of the present utility model;

[0037] Figure 3It is the second schematic diagram of the circuit principle of an over-temperature and over-voltage protection circuit provided by an embodiment of the present utility model. Detailed implementation manners

[0038] To describe in detail the possible application scenarios, technical principles, implementable specific solutions, achievable purposes and effects of the present application, etc., the following will be described in detail in combination with the listed specific embodiments and with reference to the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0039] Referring to "embodiment" herein means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various positions in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0040] Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the technical field to which the present application belongs; the use of the relevant terms herein is only for describing specific embodiments and is not intended to limit the present application.

[0041] In the description of the present application, the phrase "and / or" is an expression used to describe the logical relationship between objects, indicating that there can be three relationships, for example, A and / or B, which means: there is A, there is B, and there is both A and B at the same time. In addition, the character " / " in this article generally represents an "or" logical relationship between the associated objects before and after.

[0042] In the present application, terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary or secondary, or order relationship between these entities or operations.

[0043] Without more limitations, in the present application, the use of "including", "comprising", "having" or other similar expressions in a statement is intended to cover non-exclusive inclusion. These expressions do not exclude that there may be other elements in the process, method or product including the said elements, so that the process, method or product including a series of elements may not only include those defined elements, but also include other elements not explicitly listed, or also include elements inherent to this process, method or product.

[0044] Similar to the understanding in the "Examination Guidelines", in this application, expressions such as "greater than", "less than", "exceeding" are understood to exclude the corresponding number; expressions such as "above", "below", "within" are understood to include the corresponding number. In addition, in the description of the embodiments of this application, the meaning of "multiple" is two or more (including two). Similar expressions related to "many", such as "multiple groups", "multiple times", etc., are understood in this way, unless otherwise specifically defined.

[0045] In the description of the embodiments of this application, the spatially related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "perpendicular", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the specific embodiment or the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the specific embodiments of this application or for the reader to understand, rather than indicating or implying that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of this application.

[0046] Unless otherwise clearly specified or limited, in the description of the embodiments of this application, the terms "installed", "connected", "joined", "fixed", "set", etc. should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two components or the interaction relationship between two components. For those skilled in the art to which this application pertains, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0047] The embodiment of the present utility model provides an over-temperature and over-pressure protection circuit, which is connected between the power supply end and the load end, aiming to comprehensively ensure the stable operation of the circuit system. The protection circuit includes a first switching element and a temperature-sensitive element; wherein,

[0048] The first switching element serves as a key control point for circuit on / off. Its input end is directly connected to the power supply end to ensure stable input of electric energy. At the same time, its output end is closely connected to the load end, responsible for delivering electric energy to the load and driving it to work normally. Particularly importantly, the control end of the first switching element is connected to the output end of the temperature-sensitive element through a specific path. This design enables the state of the switching element to be flexibly adjusted along with the response of the temperature-sensitive element.

[0049] The temperature-sensitive element, as the core sensing component of this circuit, has its input end also connected to the power supply end to obtain the necessary operating voltage and play the role of voltage division. The output end of the temperature-sensitive element, through a carefully designed circuit path, directly acts on the control end of the first switching element. This connection mechanism ensures that when there are temperature abnormalities or voltage fluctuations in the circuit, the temperature-sensitive element can quickly sense and respond accordingly, and then precisely control the on / off state of the first switching element by adjusting its output signal.

[0050] It should be noted that in this embodiment, by cleverly combining the above discrete components, a protection circuit with low cost, simple structure and easy implementation is constructed. This protection circuit can sensitively respond to temperature changes and voltage fluctuations in the circuit. By utilizing the temperature characteristics of the temperature-sensitive element and combining with the voltage division of the temperature-sensitive element, it realizes precise control of the state of the first switching element, and then cuts off the power supply path when necessary, effectively preventing circuit damage or safety accidents caused by overheating or overvoltage. This not only significantly improves the overall reliability and safety of the circuit system, but also promotes the continuous optimization of its operating efficiency.

[0051] Please refer to Figure 1 , in an implementation manner of this embodiment, the first MOS transistor Q1 is specifically selected as the key first switching element, and the temperature-sensitive element is served by the triode Q2. The two work together to jointly construct a protection system that can accurately monitor and effectively respond to circuit temperature and voltage abnormalities.

[0052] Specific connection details:

[0053] Connection of the first MOS transistor Q1: As the core switching component in the circuit, the source electrode of the first MOS transistor Q1 is directly connected to the power supply end, which ensures stable power input. Its drain electrode is closely connected to the load end, responsible for transmitting the processed electrical energy to the load to drive its normal operation. Particularly crucial is that the gate (Gate) of the first MOS transistor Q1, as the control signal input end, is connected to the collector of the triode Q2 through a specific circuit path. This design enables the output state of the triode Q2 to directly affect the conduction and cut-off of the first MOS transistor Q1, thereby realizing precise control of the circuit path.

[0054] Connection of the triode Q2: As a temperature-sensitive element, the triode Q2 plays a crucial role in the circuit. Its emitter and base are both connected to the power supply end to obtain the necessary operating voltage and play the role of voltage division. It should be noted that the collector of the triode Q2 is connected to GND. This connection method enables the triode Q2 to utilize its own temperature characteristics to change the current between its collector and emitter when the circuit temperature or voltage is abnormal, and then affect the state of the first MOS transistor Q1 through the gate.

[0055] In this embodiment, by carefully selecting and combining two discrete components, namely MOS transistors and bipolar transistors, a protection circuit with a compact structure and perfect functions is constructed. This circuit not only has a low cost, but also is easy to implement and maintain. At the same time, it retains a high degree of flexibility and scalability, facilitating adjustment and optimization according to specific requirements.

[0056] This embodiment further refines the design of the over-temperature and over-voltage protection circuit, and particularly introduces a resistor network as a key component to enhance the protection function and stability of the circuit. In this embodiment, the over-temperature and over-voltage protection circuit further includes a resistor network, and the resistor network is connected to the first switching element, jointly constituting an efficient and reliable circuit protection system.

[0057] It should be noted that a resistor network usually consists of multiple resistor elements, and these resistor elements are connected to the circuit in a specific manner to achieve specific circuit functions. In this embodiment, the specific composition and connection method of the resistor network may vary according to design requirements. Generally speaking, it may include series resistors, parallel resistors, or complex hybrid networks.

[0058] Please refer to Figure 1 again. In one embodiment of this embodiment, the resistor network includes a second resistor R2, a third resistor R3, and a fourth resistor R4;

[0059] The base of the bipolar transistor Q2 is connected to the power supply terminal through the third resistor R3, and the collector of the bipolar transistor Q2 is connected to GND through the second resistor R2;

[0060] The fourth resistor R4 is connected between the base of the bipolar transistor Q2 and GND.

[0061] The following is a detailed description of over-temperature protection and over-voltage protection:

[0062] (1) Over-temperature protection function:

[0063] In a high-temperature scenario, because the energy gap of semiconductor materials decreases with increasing temperature, the Vbe (base-emitter voltage) of the bipolar transistor Q2 decreases, the Ic (collector current) increases, the gate voltage of the first MOS transistor Q1 increases, and the Vgs (gate-source voltage, Vgs = Ic * R2) of the first MOS transistor Q1 is less than the threshold value, and the first MOS transistor Q1 turns off to cut off the power supply path.

[0064] In a normal-temperature scenario, the Ic (collector current) of the bipolar transistor Q2 decreases, the gate voltage of the first MOS transistor Q1 decreases, the Vgs (gate-source voltage, Vgs = Ic * R2) of the first MOS transistor Q1 is greater than the threshold value, and the first MOS transistor Q1 turns on to connect the power supply path.

[0065] For the determination of the above-mentioned threshold, it can be based on the Vbe and Ic current curves in the transistor specification sheet. For example, Figure 2 as shown, it is defined that over-temperature protection needs to be triggered above a high temperature (such as 60°). Since the third resistor R3 and the fourth resistor R4 are used for voltage division, the threshold can be determined through calculation for triggering over-temperature protection. Given that this content has been implemented in the prior art in many ways and is not the focus of the design of this solution, it will not be elaborated in depth here.

[0066] (2) Over-voltage protection function:

[0067] When the power supply voltage increases, resulting in an increase in the voltage division on the base resistor of the transistor Q2, the voltage difference between the base and emitter of the transistor Q2 will increase. Under normal circumstances, this will cause an increase in Ib (base current), and further an increase in Ic (collector current). Similar to the over-temperature protection mechanism, the increase in Ic (collector current) will cause the gate voltage of the first MOS transistor Q1 to increase, and finally the first MOS transistor Q1 will be turned off to cut off the power supply path, thereby protecting the circuit from damage caused by excessive voltage.

[0068] Please refer to Figure 1 again. In another implementation manner of this embodiment, the over-temperature and over-voltage protection circuit further includes a first resistor R1, which further enhances the stability and reliability of the circuit;

[0069] The gate of the first MOS transistor Q1 is connected to the collector of the transistor Q2 through the first resistor R1.

[0070] Specifically, the gate of the first MOS transistor Q1 is not directly connected to the collector of the transistor Q2, but is electrically connected through the first resistor R1. This design not only ensures a smooth transition of current during transmission between the gate and the collector, but also effectively limits the sudden change of the gate voltage, preventing transient effects that may be caused by excessive voltage fluctuations, thereby protecting the first MOS transistor Q1 from damage.

[0071] Please refer to Figure 1 again. In another implementation manner of this embodiment, the over-temperature and over-voltage protection circuit further includes a first capacitor C1;

[0072] The first capacitor C1 is connected between the source and the gate of the first MOS transistor Q1.

[0073] Specifically, this design not only enriches the composition of the circuit, but also improves the performance and stability of the circuit in many aspects;

[0074] First, from the perspective of the protection mechanism, the addition of the first capacitor C1 provides an additional voltage buffer layer for the gate of the first MOS transistor Q1. When the circuit encounters abnormal conditions such as overheating or overvoltage, the first capacitor C1 can absorb or release a certain amount of charge, thereby slowing down the mutation speed of the gate voltage and preventing damage to the first MOS transistor Q1 caused by excessive voltage fluctuations. This "smoothing" effect helps to ensure that the first MOS transistor Q1 can safely switch its operating state as expected, thus effectively realizing the over-temperature and over-voltage protection function.

[0075] Secondly, from the perspective of circuit stability, the first capacitor C1 and the first resistor R1 construct a simple RC (resistor-capacitor) filter network in the circuit. This filter network can filter out noise signals from the power supply or other circuit parts, reduce their interference with the gate voltage of the MOS transistor, and thus ensure that the MOS transistor can operate stably within its predetermined voltage range.

[0076] Optionally, the first MOS transistor Q1 can be selected as an NMOS transistor.

[0077] It should be noted that, generally, if the MOS transistor is used in the main path and connected between the power supply and the load, the MOS transistor is preferably selected as an NMOS transistor because the NMOS transistor can block the current from the power supply to the load when it is turned off and allow the current to flow through when it is turned on.

[0078] Optionally, the triode Q2 can be selected as a PNP type triode.

[0079] It should be noted that, in order to cooperate with the NMOS transistor and realize the required logic function, the triode Q2 is preferably selected as a PNP type triode. When the base voltage of the PNP type triode decreases, the collector current will increase (compared with the NPN type triode), and this characteristic can be combined with the gate control logic of the NMOS transistor to realize the automatic power-off protection in case of over-temperature and over-voltage.

[0080] Please refer to Figure 3 , in another implementation manner of this embodiment, the over-temperature and over-voltage protection circuit includes two modes. One is the mode in which the switching of the first MOS transistor Q1 is completely controlled by the temperature characteristic of the triode Q2, and the other is controlled by a processor (such as an SOC), thus becoming a controllable circuit, that is, the over-temperature and over-voltage protection circuit further includes a second switching element; the input end of the second switching element is connected to GND, the output end of the second switching element is connected to the base of the triode Q2, and the control end of the second switching element is connected to the processor.

[0081] Please refer to again Figure 3 , in an implementation manner of this embodiment, the second MOS transistor Q3 is particularly selected as the key second switching element;

[0082] Specifically, the gate of the second MOS transistor Q3 is connected to the processor, the drain of the second MOS transistor Q3 is connected to the base of the transistor Q2, and the source of the second MOS transistor Q3 is connected to GND.

[0083] It should be noted that the processor can control the on / off of the second MOS transistor Q3 by changing the output state, making the voltage-dividing resistor ineffective, thereby controlling the on / off of the first MOS transistor Q1, and then controlling the on / off of the power supply path, without being affected by the over-temperature or over-voltage protection mechanism.

[0084] In this embodiment, the gate of the second MOS transistor Q3 is connected to the GPIO (General-Purpose Input / Output) interface of the processor.

[0085] It should be noted that the processor can output a high-level or low-level signal through its GPIO interface to control the on or off state of the second MOS transistor Q3. This design enables the circuit to dynamically adjust its working state according to the real-time judgment of the processor or the preset algorithm logic, thereby enhancing the intelligence and adaptability of the entire system.

[0086] In addition, as a basic way for the processor to communicate with external devices, the GPIO interface has the characteristics of being simple to use and highly flexible. Controlling the state of the MOS transistor through the GPIO interface not only simplifies the circuit design but also reduces the system cost. At the same time, it also facilitates subsequent circuit debugging and maintenance.

[0087] Please refer to again Figure 3 , in another implementation manner of this embodiment, the over-temperature and over-voltage protection circuit further includes a sixth resistor R6;

[0088] The gate of the second MOS transistor Q3 is connected to the processor through the sixth resistor R6.

[0089] It should be noted that the sixth resistor R6 limits the current flowing from the GPIO interface of the processor to the gate of the second MOS transistor Q3, preventing excessive current from damaging the gate of the second MOS transistor Q3.

[0090] Please refer to again Figure 3 , in another implementation manner of this embodiment, the over-temperature and over-voltage protection circuit further includes a fifth resistor R5;

[0091] The fifth resistor R5 is connected between the gate of the second MOS transistor Q3 and GND.

[0092] It should be noted that the fifth resistor R5 serves as a pull-down resistor to ensure that when the processor does not output a high-level signal to the gate of the second MOS transistor Q3, the gate of the second MOS transistor Q3 can be stably maintained at a low-level state. This helps prevent false triggering caused by noise or floating voltage in the circuit and ensures that the second MOS transistor Q3 remains cutoff in an uncontrolled state.

[0093] Optionally, the second MOS transistor Q3 can be selected as an NMOS transistor.

[0094] Although terms such as MOS transistors, bipolar transistors, and resistors are used more frequently in this application, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0095] An over-temperature and over-voltage protection circuit provided by the present invention is built from several discrete devices and has the advantages of low cost, simple circuit, and easy implementation. By utilizing the temperature characteristics of the temperature-sensitive element and combining with the voltage division of the temperature-sensitive element, the on-off control of the first switching element can be realized, thereby realizing the on-off control of the power supply path and achieving the purpose of over-temperature and over-voltage protection, which can improve the reliability, safety, and operating efficiency of the entire circuit system.

[0096] Finally, it should be noted that although the above embodiments have been described in the text and drawings of the specification of this application, the patent protection scope of this application cannot be limited thereby. Any technical solutions obtained by equivalent structure or equivalent process substitution or modification based on the essential concept of this application and using the content recorded in the text and drawings of the specification of this application, as well as directly or indirectly implementing the technical solutions of the above embodiments in other related technical fields, are all included in the patent protection scope of this application.

Claims

1. An over-temperature and over-voltage protection circuit, connected between a power supply end and a load end, characterized in that: It includes a first switch element and a temperature sensitive element; wherein, The input end of the first switch element is connected to the power supply end, the output end of the first switch element is connected to the load end, and the control end of the first switch element is connected to the output end of the temperature sensitive element; The input end of the temperature sensitive element is connected to the power supply end, and the output end of the temperature sensitive element is connected to the control end of the first switch element.

2. The over-temperature and over-voltage protection circuit according to claim 1, characterized in that: The first switch element is a first MOS tube Q1, and the temperature sensitive element is a transistor Q2; The source of the first MOS transistor Q1 is connected to the power supply end, the drain of the first MOS transistor Q1 is connected to the load end, and the gate of the first MOS transistor Q1 is connected to the collector of the transistor Q2; The emitter and base of the transistor Q2 are connected to the power supply end respectively, and the collector of the transistor Q2 is connected to GND.

3. The over-temperature and over-voltage protection circuit according to claim 2, characterized in that: Also included is a resistor network; The resistor network is connected to the first switch element.

4. The over-temperature and over-voltage protection circuit according to claim 3, characterized in that: The resistor network includes a second resistor R2, a third resistor R3 and a fourth resistor R4; The base of the transistor Q2 is connected to the power supply end through the third resistor R3, and the collector of the transistor Q2 is connected to GND through the second resistor R2; The fourth resistor R4 is connected between the base of the transistor Q2 and GND.

5. The over-temperature and over-voltage protection circuit according to claim 4, characterized in that: Also includes a first resistor R1; The gate of the first MOS transistor Q1 is connected to the collector of the transistor Q2 through the first resistor R1.

6. The over-temperature and over-voltage protection circuit according to claim 5, characterized in that: Also includes a first capacitor C1; The first capacitor C1 is connected between the source and the gate of the first MOS transistor Q1.

7. The over-temperature and over-voltage protection circuit according to claim 6, characterized in that: Also comprising a second switching element; The input end of the second switch element is connected to GND, the output end of the second switch element is connected to the base of the transistor Q2, and the control end of the second switch element is connected to the processor.

8. The over-temperature and over-voltage protection circuit according to claim 7, characterized in that: The second switch element is a second MOS tube Q3; The gate of the second MOS transistor Q3 is connected to the processor, the drain of the second MOS transistor Q3 is connected to the base of the transistor Q2, and the source of the second MOS transistor Q3 is connected to GND.

9. The over-temperature and over-voltage protection circuit according to claim 8, characterized in that: Also includes a sixth resistor R6; The gate of the second MOS transistor Q3 is connected to the processor through the sixth resistor R6.

10. The over-temperature and over-voltage protection circuit according to claim 9, characterized in that: Also includes a fifth resistor R5; The fifth resistor R5 is connected between the gate of the second MOS transistor Q3 and GND.

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