A voltage protection circuit of an MCU chip

Abstract

The application discloses a voltage protection circuit of MCU chip, and relates to the technical field of circuit protection, comprising an input protection module, which is used for controlling a power supply module to provide electric energy for a load module; a voltage sampling and conditioning module, which is used for voltage sampling and signal amplification conditioning; a positive and negative voltage comparison module, which is used for positive and negative overvoltage judgment; a signal transmission module, which is used for signal filtering and transmission; an intelligent control module, which is used for receiving signals through an MCU circuit and controlling the module to work; and an isolation control module, which is used for isolating and driving a self-recovery protection control module to periodically control the input protection module to work. The voltage protection circuit of the MCU chip detects the working electric energy of the load module, judges the voltage conditions of the positive half cycle and the negative half cycle of alternating current, receives and analyzes the voltage conditions through the MCU circuit, and controls the self-recovery protection control module to periodically control the input protection module to work in protection when overvoltage short circuit occurs.

Description

Technical Field

[0001] This invention relates to the field of circuit protection technology, specifically a voltage protection circuit for an MCU chip. Background Technology

[0002] With the development of intelligent electronic device technology, the requirements for the reliability and safety of electronic devices are becoming increasingly stringent. Therefore, it is common practice to detect the electrical energy input to electronic devices to prevent overvoltage and short circuits. Existing voltage protection circuits sample electrical energy using a resistor divider circuit, which is received by the MCU chip and processed according to internally set thresholds. This requires a large amount of programming. Furthermore, when protecting AC power, the AC power needs to be rectified or detected using a peak circuit, making the detection method quite complex. Moreover, since the MCU cannot detect negative voltages, it cannot accurately detect the negative half-cycle of AC power, resulting in inaccurate overvoltage and short circuit protection. Therefore, improvements are needed. Summary of the Invention

[0003] This invention provides a voltage protection circuit for an MCU chip to solve the problems mentioned in the background art.

[0004] According to an embodiment of the present invention, a voltage protection circuit for an MCU chip is provided. The voltage protection circuit for the MCU chip includes: a power supply module, an input protection module, a load module, a voltage sampling and conditioning module, a positive and negative voltage comparison module, a signal transmission module, an intelligent control module, an isolation control module, and a self-recovery protection control module.

[0005] The power module is used to provide the circuit with the required electrical energy;

[0006] The input protection module is connected to the power supply module and is used to control the power transmission of the power supply module by turning on the relay protection circuit.

[0007] The load module is connected to the input protection module and is used to receive electrical energy transmitted by the input protection module and provide electrical energy to the load system.

[0008] The voltage sampling and conditioning module is connected to the load module and is used to sample the voltage of the electrical energy input to the load module and output a voltage signal, and to detect the voltage signal, amplify and condition it and output it.

[0009] The positive and negative voltage comparison module is connected to the voltage sampling and conditioning module, and is used to perform positive overvoltage judgment and negative overvoltage judgment on the signal output by the voltage sampling and conditioning module through the positive value comparison circuit and the negative value comparison circuit, and output the first judgment signal and the second judgment signal respectively.

[0010] The signal transmission module is connected to the positive and negative voltage comparison module. It is used to filter the first judgment signal and the second judgment signal through the RC filter circuit and transmit them to the intelligent control module. It is also used to output a protection control signal through the isolation trigger circuit.

[0011] The intelligent control module is connected to the signal transmission module and is used to receive the first judgment signal and the second judgment signal through the MCU circuit and analyze the voltage fault cycle, and to receive the protection control signal and output the first control signal.

[0012] The isolation control module is connected to the intelligent control module and is used to receive the first control signal and output a negative trigger signal through the isolation drive circuit.

[0013] The self-recovery protection control module is connected to the isolation control module and the input protection module, and is used to receive the negative trigger signal and control the periodic operation of the relay protection circuit through the timing control circuit.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The voltage protection circuit of the MCU chip of the present invention uses a voltage sampling and conditioning module to detect the working power of the load module, and a positive and negative voltage comparison module to perform positive overvoltage judgment and negative overvoltage judgment on the detected signal through a positive value comparison circuit and a negative value comparison circuit, respectively, to determine the voltage status of the positive and negative half-cycles of the AC power. The signal transmission module processes the signal and the MCU circuit receives and analyzes it, thereby improving the voltage detection accuracy of the AC power. In the event of overvoltage and short circuit, the MCU circuit controls the isolation control module to output a negative trigger signal, which controls the self-recovery protection control module to periodically control the relay protection circuit to perform periodic protection, thereby realizing the self-recovery control of the circuit and improving the safety of the circuit. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic block diagram of a voltage protection circuit for an MCU chip, provided as an example of the present invention.

[0017] Figure 2 A circuit diagram of a voltage protection circuit for an MCU chip provided as an example of the present invention.

[0018] Figure 3 The connection circuit diagram of the self-recovery protection control module provided for an example of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1, please refer to Figure 1 A voltage protection circuit for an MCU chip includes: a power supply module 1, an input protection module 2, a load module 3, a voltage sampling and conditioning module 4, a positive and negative voltage comparison module 5, a signal transmission module 6, an intelligent control module 7, an isolation control module 8, and a self-recovery protection control module 9.

[0021] Specifically, the power module 1 is used to provide the required electrical energy to the circuit;

[0022] Input protection module 2, connected to the power supply module 1, is used to control the power transmission of the power supply module 1 via the relay protection circuit;

[0023] The load module 3 is connected to the input protection module 2 and is used to receive the electrical energy transmitted by the input protection module 2 and provide electrical energy to the load system.

[0024] The voltage sampling and conditioning module 4 is connected to the load module 3 and is used to sample the voltage of the electrical energy input to the load module 3 and output a voltage signal, and to detect the voltage signal, amplify and condition it and output it.

[0025] The positive and negative voltage comparison module 5 is connected to the voltage sampling and conditioning module 4, and is used to perform positive overvoltage judgment and negative overvoltage judgment on the signal output by the voltage sampling and conditioning module 4 through the positive value comparison circuit and the negative value comparison circuit, and output the first judgment signal and the second judgment signal respectively.

[0026] The signal transmission module 6 is connected to the positive and negative voltage comparison module 5. It is used to filter the first judgment signal and the second judgment signal through the RC filter circuit and transmit them to the intelligent control module 7. It is used to output protection control signal through the isolation trigger circuit.

[0027] The intelligent control module 7 is connected to the signal transmission module 6 and is used to receive the first judgment signal and the second judgment signal through the MCU circuit and analyze the voltage fault cycle, and to receive the protection control signal and output the first control signal.

[0028] The isolation control module 8 is connected to the intelligent control module 7 and is used to receive the first control signal and output a negative trigger signal through the isolation drive circuit.

[0029] The self-recovery protection control module 9 is connected to the isolation control module 8 and the input protection module 2, and is used to receive the negative trigger signal and control the periodic operation of the relay protection circuit through the timing control circuit.

[0030] In a specific embodiment, the power supply module 1 can be powered by AC or DC power, which will not be elaborated here; the input protection module 2 uses a relay protection circuit to control the connection between the power supply module 1 and the load module 3; the load module 3 is an electronic component that consumes electrical energy, and the specific load circuit selected will not be elaborated here; the voltage sampling and conditioning module 4 can use a resistor divider circuit and an operational amplifier circuit, with the resistor divider circuit sampling the voltage and the operational amplifier circuit amplifying the signal; the positive and negative voltage comparison module 5 can use a positive comparison circuit and a negative comparison circuit to perform positive overvoltage judgment and negative overvoltage judgment on the signal output by the voltage sampling and conditioning module 4, respectively; the signal transmission module 6 can use an RC filter circuit to filter the input signal and also uses an isolation trigger circuit to provide protection control commands to the intelligent control module 7; the intelligent control module 7 can use an MCU circuit to receive signals and control the module, which will not be elaborated here; the isolation control module 8 can use an isolation drive circuit to output a negative trigger signal; the self-recovery protection control module 9 can use a timing control circuit to control the periodic operation of the relay protection circuit.

[0031] Example 2, based on Example 1, please refer to... Figure 2 and Figure 3 The input protection module 2 includes a first relay switch K1-1; the voltage sampling and conditioning module 4 includes a first resistor R1 and a second resistor R2.

[0032] Specifically, one end of the first relay switch K1-1 is connected to the power module 1, the other end of the first relay switch K1-1 is connected to the first end of the first resistor R1 and the load module 3, and the second end of the first resistor R1 is connected to the ground through the second resistor R2.

[0033] Furthermore, the voltage sampling and conditioning module 4 includes a third resistor R3, a fourth resistor R4, a first operational amplifier OP1, a fifth resistor R5, a first capacitor C1, a sixth resistor R6, and a second capacitor C2.

[0034] Specifically, one end of the third resistor R3 is connected to the second end of the first resistor R1, and the other end of the third resistor R3 is connected to the inverting input of the first operational amplifier OP1 and one end of the fifth resistor R5. It is also connected to the output of the first operational amplifier OP1, the other end of the fifth resistor R5, and the first end of the sixth resistor R6 through the first capacitor C1. The non-inverting input of the first operational amplifier OP1 is connected to ground through the fourth resistor R4, and the second end of the sixth resistor R6 is connected to the positive and negative voltage comparison module 5 and connected to ground through the second capacitor C2.

[0035] In a specific embodiment, the first relay switch K1-1 can be a normally closed switch; the first resistor R1 and the second resistor R2 form a resistor voltage divider circuit for voltage sampling; the first operational amplifier OP1 can be an OP07 operational amplifier to perform flip-ampling processing on the positive and negative half-cycles of AC power; the sixth resistor R6 and the second capacitor C2 form an RC filter circuit.

[0036] Furthermore, the positive and negative voltage comparison module 5 includes a seventh resistor R7, a first comparator A1, a positive voltage threshold, a ninth resistor R9, and a sixth power supply VCC6;

[0037] Specifically, the first end of the seventh resistor R7 is connected to the second end of the sixth resistor R6, the second end of the seventh resistor R7 is connected to the non-inverting input of the first comparator A1, the inverting input of the first comparator A1 is connected to the positive voltage threshold, and the output of the first comparator A1 is connected to the signal transmission module 6 and connected to the sixth power supply VCC6 through the ninth resistor R9.

[0038] In a specific embodiment, the first comparator A1 can be an LM393 comparator, which, together with a positive voltage threshold, performs overvoltage judgment on the positive voltage output by the first operational amplifier OP1 during the negative half-cycle of AC power.

[0039] Furthermore, the positive and negative voltage comparison module 5 also includes an eighth resistor R8, a first Zener diode VD1, a second Zener diode VD2, and a tenth resistor R10;

[0040] Specifically, one end of the eighth resistor R8 is connected to the first end of the seventh resistor R7, the other end of the eighth resistor R8 is connected to the anode of the first Zener diode VD1, the cathode of the first Zener diode VD1 is connected to the cathode of the second Zener diode VD2, the anode of the second Zener diode VD2 is connected to the first end of the tenth resistor R10, and the second end of the tenth resistor R10 is connected to the signal transmission module 6.

[0041] In a specific embodiment, the first Zener diode VD1 and the second Zener diode VD2 are used as negative overvoltage judgment thresholds to judge the positive half-cycle overvoltage of the negative voltage output by the first operational amplifier OP1.

[0042] Furthermore, the signal transmission module 6 includes a third capacitor C3, an eleventh resistor R11, a tenth capacitor C10, and a fifteenth resistor R15; the intelligent control module 7 includes a first controller U1;

[0043] Specifically, one end of the third capacitor C3 is connected to the output terminal of the first comparator A1 and connected to the second IO terminal of the first controller U1 through the eleventh resistor R11, and the other end of the third capacitor C3 is grounded. One end of the fourth capacitor is connected to the second terminal of the tenth resistor R10 and connected to the third IO terminal of the first controller U1 through the fifteenth resistor R15, and the other ends of the third capacitor C3 and the fourth capacitor are both grounded.

[0044] In a specific embodiment, the third capacitor C3 and the eleventh resistor R11, the fourth capacitor and the fifteenth resistor R15 form an RC filter circuit to filter the input signal; the first controller U1 can be an MCU chip, and the specific model is not limited.

[0045] Furthermore, the signal transmission module 6 also includes a first switch VT1, a twelfth resistor R12, a first power supply VCC1, a first diode D1, a first optocoupler J1, a thirteenth resistor R13, a second diode D2, a second switch VT2, a fourteenth resistor R14, a second power supply VCC2, a sixteenth resistor R16, a seventeenth resistor R17, a third switch VT3, and a third power supply VCC3;

[0046] Specifically, the base of the first switching transistor VT1 and the base of the second switching transistor VT2 are respectively connected to the output terminal of the first comparator A1 and the second terminal of the tenth resistor R10. The collector of the first switching transistor VT1 is connected to the first power supply VCC1 through the twelfth resistor R12. The emitter of the first switching transistor VT1 is connected to the cathode of the first diode D1 and the first terminal of the first optocoupler J1. The emitter of the second switching transistor VT2 is connected to the anode of the second diode D2 and is connected to the second terminal of the first optocoupler J1 through the thirteenth resistor R13. The third terminal of the first optocoupler J1 is connected to the base of the third switching transistor VT3 and is connected to one end of the seventeenth resistor R17 and the third power supply VCC3 through the sixteenth resistor R16. The other end of the seventeenth resistor R17 is connected to the collector of the third switching transistor VT3 and the first IO terminal of the first controller U1. The emitter of the third switching transistor VT3 and the fourth terminal of the first optocoupler J1 are both grounded. The anode of the first diode D1 and the cathode of the second diode D2 are both grounded. The collector of the second switching transistor VT2 is connected to the second power supply VCC2 through the fourteenth resistor R14.

[0047] In a specific embodiment, the first switch VT1 can be an NPN transistor, the second switch VT2 can be a PNP transistor, and it is used to trigger the first optocoupler J1 to transmit signals; the first optocoupler J1 can be a PC817 optocoupler; the third switch VT3 can be an NPN transistor, which is controlled by the first optocoupler J1 and provides protection control signals to the first controller U1.

[0048] Furthermore, the isolation control module 8 includes a second optocoupler J2, an eighteenth resistor R18, a fourth power supply VCC4, a twentieth resistor R20, a nineteenth resistor R19, a fifth capacitor C5, a fourth switching transistor VT4, a twenty-first resistor R21, an eighth capacitor C8, and a fifth power supply VCC5.

[0049] Specifically, the fourth power supply VCC4 is connected to the first terminal of the second optocoupler J2 through the eighteenth resistor R18. The second terminal of the second optocoupler J2 is connected to the fourth IO terminal of the first controller U1. The third terminal of the first optocoupler J1 is connected to the fifth power supply VCC5, one terminal of the nineteenth resistor R19, and the first terminal of the twenty-first resistor R21. The second terminal of the twentieth resistor R20 is connected to the other terminal of the nineteenth resistor R19 and the collector of the fourth switch VT4 through the eighth capacitor C8. The base of the fourth switch VT4 is connected to the fourth terminal of the second optocoupler J2 and one terminal of the fifth capacitor C5, and is connected to the other terminal of the fifth capacitor C5, the emitter of the fourth switch VT4, and ground through the twentieth resistor R20.

[0050] In a specific embodiment, the second optocoupler J2 can be a PC817 optocoupler to transmit the control signal output by the first controller U1 and control the working state of the fourth switch VT4; the fourth switch VT4 can be an NPN transistor, which, together with the nineteenth resistor R19, the twenty-first resistor R21, and the fifth resistor R5, outputs a negative trigger signal.

[0051] Furthermore, the self-recovery protection control module 9 includes a twenty-second resistor R22, a sixth capacitor C6, a timer U2, and a seventh capacitor C7;

[0052] Specifically, one end of the 22nd resistor R22, the fourth and eighth ends of the timer U2 are connected to the fifth power supply VCC5, the second end of the timer U2 is connected to the second end of the 21st resistor R21, the other end of the 22nd resistor R22 is connected to the sixth and seventh ends of the timer U2 and grounded through the sixth capacitor C6, the fifth end of the timer U2 is connected to the first end of the timer U2 and ground through the seventh capacitor C7, and the third end of the timer U2 is connected to the input protection module 2.

[0053] In a specific embodiment, the timer U2 mentioned above can be an NE555 integrated circuit.

[0054] Furthermore, the input protection module 2 also includes a twenty-third resistor R23, a twenty-fourth resistor R24, a fifth switch VT5, a first relay K1, and a third diode D3;

[0055] Specifically, one end of the 23rd resistor R23 is connected to the third terminal of the timer U2, and the other end of the 23rd resistor R23 is connected to the base of the fifth switch VT5 and connected to the emitter and ground of the fifth switch VT5 through the 24th resistor R24. The collector of the fifth switch VT5 is connected to the anode of the third diode D3 and one end of the first relay K1. The other end of the first relay K1 and the cathode of the third diode D3 are connected to the eighth terminal of the timer U2.

[0056] In a specific embodiment, the fifth switch VT5 can be an NPN transistor used to control the working state of the first relay K1; the first relay K1 is used to control the closed state of the first relay switch K1-1.

[0057] This invention discloses a voltage protection circuit for an MCU chip. Power is supplied by a power module 1, providing either AC or DC power. When the input is AC, the electrical energy is transmitted to the load module 3 via a first relay switch K1-1. The signal is sampled by a first resistor R1 and a second resistor R2, and amplified by a first operational amplifier OP1. When the positive half-cycle of the AC power is detected, the first operational amplifier OP1 outputs a negative voltage; when the negative half-cycle is detected, it outputs a positive voltage. The negative voltage is used for positive half-cycle overvoltage detection by a first Zener diode VD1 and a second Zener diode VD2, while the positive voltage is used for negative half-cycle overvoltage detection by a first comparator A1. When the first operational amplifier OP1 outputs a high level, the negative half-cycle of the AC power is overvoltage, triggering the first switch VT1 to conduct. The signal output by the first operational amplifier OP1 is transmitted to the second I / O terminal of the first controller U1 via an eleventh resistor R11 and a third capacitor C3 for negative half-cycle overvoltage recording. The first optocoupler J1 then conducts, controlling the third switch V... When T3 is cut off, the first IO terminal of the first controller U1 receives the protection control signal. When the first Zener diode VD1 is broken down and the second Zener diode VD2 is turned on, it is a positive half-cycle overvoltage. The negative voltage triggers the second switch VT2 to turn on. Similarly, the third IO terminal of the first controller U1 records the positive half-cycle overvoltage and controls the first optocoupler J1 to turn on. The first IO terminal of the first controller U1 receives the protection control signal. As long as the first IO terminal of the first controller U1 receives the protection control signal, the fourth IO terminal of the first controller U1 will output the first control signal in the form of a pulse. The second optocoupler J2 and the fourth switch VT4 process the signal to provide a negative trigger signal for the timer U2, triggering the timer U2 to output a high level to control the operation of the first relay K1, causing the first relay switch K1-1 to open and disconnect the power module 1. After the timing ends, the first relay switch K1-1 will be closed again to detect whether the circuit is still in a fault state. The detection of DC power is the same as the positive half-cycle detection method for AC power.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A voltage protection circuit for an MCU chip, characterized in that, The voltage protection circuit of this MCU chip includes: a power supply module, an input protection module, a load module, a voltage sampling and conditioning module, a positive and negative voltage comparison module, a signal transmission module, an intelligent control module, an isolation control module, and a self-recovery protection control module. The power module is used to provide the circuit with the required electrical energy; The input protection module is connected to the power supply module and is used to control the power transmission of the power supply module by turning on the relay protection circuit. The load module is connected to the input protection module and is used to receive electrical energy transmitted by the input protection module and provide electrical energy to the load system. The voltage sampling and conditioning module is connected to the load module and is used to sample the voltage of the electrical energy input to the load module and output a voltage signal, and to detect the voltage signal, amplify and condition it and output it. The positive and negative voltage comparison module is connected to the voltage sampling and conditioning module, and is used to perform positive overvoltage judgment and negative overvoltage judgment on the signal output by the voltage sampling and conditioning module through the positive value comparison circuit and the negative value comparison circuit, and output the first judgment signal and the second judgment signal respectively. The signal transmission module is connected to the positive and negative voltage comparison module. It is used to filter the first judgment signal and the second judgment signal through the RC filter circuit and transmit them to the intelligent control module. It is also used to output a protection control signal through the isolation trigger circuit. The intelligent control module is connected to the signal transmission module and is used to receive the first judgment signal and the second judgment signal through the MCU circuit and analyze the voltage fault cycle, and to receive the protection control signal and output the first control signal. The isolation control module is connected to the intelligent control module and is used to receive the first control signal and output a negative trigger signal through the isolation drive circuit. The self-recovery protection control module is connected to the isolation control module and the input protection module, and is used to receive the negative trigger signal and control the periodic operation of the relay protection circuit through the timing control circuit. The input protection module includes a first relay switch; the voltage sampling and conditioning module includes a first resistor and a second resistor. One end of the first relay switch is connected to the power module, and the other end of the first relay switch is connected to the first end of the first resistor and the load module. The second end of the first resistor is connected to the ground terminal through the second resistor. The voltage sampling and conditioning module includes a third resistor, a fourth resistor, a first operational amplifier, a fifth resistor, a first capacitor, a sixth resistor, and a second capacitor; One end of the third resistor is connected to the second end of the first resistor, and the other end of the third resistor is connected to the inverting input of the first operational amplifier and one end of the fifth resistor. It is also connected to the output of the first operational amplifier, the other end of the fifth resistor, and the first end of the sixth resistor through the first capacitor. The non-inverting input of the first operational amplifier is connected to ground through the fourth resistor, and the second end of the sixth resistor is connected to the positive and negative voltage comparison module and connected to ground through the second capacitor. The positive and negative voltage comparison module includes a seventh resistor, a first comparator, a positive voltage threshold, a ninth resistor, and a sixth power supply; The first end of the seventh resistor is connected to the second end of the sixth resistor, the second end of the seventh resistor is connected to the non-inverting input of the first comparator, the inverting input of the first comparator is connected to the positive voltage threshold, and the output of the first comparator is connected to the signal transmission module and connected to the sixth power supply through the ninth resistor. The positive and negative voltage comparison module also includes an eighth resistor, a first Zener diode, a second Zener diode, and a tenth resistor; One end of the eighth resistor is connected to the first end of the seventh resistor, the other end of the eighth resistor is connected to the anode of the first Zener diode, the cathode of the first Zener diode is connected to the cathode of the second Zener diode, the anode of the second Zener diode is connected to the first end of the tenth resistor, and the second end of the tenth resistor is connected to the signal transmission module.

2. The voltage protection circuit for an MCU chip according to claim 1, characterized in that, The signal transmission module includes a third capacitor, an eleventh resistor, a tenth capacitor, and a fifteenth resistor; the intelligent control module includes a first controller. One end of the third capacitor is connected to the output of the first comparator and then to the second I / O terminal of the first controller through the eleventh resistor. The other end of the third capacitor is grounded. One end of the fourth capacitor is connected to the second terminal of the tenth resistor and then to the third I / O terminal of the first controller through the fifteenth resistor. The other ends of both the third and fourth capacitors are grounded.

3. The voltage protection circuit for an MCU chip according to claim 2, characterized in that, The signal transmission module further includes a first switching transistor, a twelfth resistor, a first power supply, a first diode, a first optocoupler, a thirteenth resistor, a second diode, a second switching transistor, a fourteenth resistor, a second power supply, a sixteenth resistor, a seventeenth resistor, a third switching transistor, and a third power supply; The bases of the first and second switching transistors are respectively connected to the output of the first comparator and the second terminal of the tenth resistor. The collector of the first switching transistor is connected to the first power supply through the twelfth resistor. The emitter of the first switching transistor is connected to the cathode of the first diode and the first terminal of the first optocoupler. The emitter of the second switching transistor is connected to the anode of the second diode and is connected to the second terminal of the first optocoupler through the thirteenth resistor. The third terminal of the first optocoupler is connected to the base of the third switching transistor and is connected to one end of the seventeenth resistor and the third power supply through the sixteenth resistor. The other end of the seventeenth resistor is connected to the collector of the third switching transistor and the first I / O terminal of the first controller. The emitter of the third switching transistor and the fourth terminal of the first optocoupler are both grounded. The anode of the first diode and the cathode of the second diode are both grounded. The collector of the second switching transistor is connected to the second power supply through the fourteenth resistor.

4. The voltage protection circuit for an MCU chip according to claim 2, characterized in that, The isolation control module includes a second optocoupler, an eighteenth resistor, a fourth power supply, a twentieth resistor, a nineteenth resistor, a fifth capacitor, a fourth switching transistor, a twenty-first resistor, an eighth capacitor, and a fifth power supply. The fourth power supply is connected to the first end of the second optocoupler through the eighteenth resistor. The second end of the second optocoupler is connected to the fourth IO terminal of the first controller. The third end of the first optocoupler is connected to the fifth power supply, one end of the nineteenth resistor, and the first end of the twenty-first resistor. The second end of the twentyth resistor is connected to the other end of the nineteenth resistor and the collector of the fourth switch through the eighth capacitor. The base of the fourth switch is connected to the fourth end of the second optocoupler and one end of the fifth capacitor, and is connected to the other end of the fifth capacitor, the emitter of the fourth switch, and ground through the twentyth resistor.

5. The voltage protection circuit for an MCU chip according to claim 4, characterized in that, The self-recovery protection control module includes a twenty-second resistor, a sixth capacitor, a timer, and a seventh capacitor; One end of the 22nd resistor, the fourth and eighth ends of the timer are connected to the fifth power supply. The second end of the timer is connected to the second end of the 21st resistor. The other end of the 22nd resistor is connected to the sixth and seventh ends of the timer and grounded through the sixth capacitor. The fifth end of the timer is connected to the first end of the timer and ground through the seventh capacitor. The third end of the timer is connected to the input protection module.

6. The voltage protection circuit for an MCU chip according to claim 5, characterized in that, The input protection module also includes a twenty-third resistor, a twenty-fourth resistor, a fifth switching transistor, a first relay, and a third diode; One end of the 23rd resistor is connected to the third terminal of the timer, and the other end of the 23rd resistor is connected to the base of the fifth switching transistor and connected to the emitter and ground of the fifth switching transistor through the 24th resistor. The collector of the fifth switching transistor is connected to the anode of the third diode and one end of the first relay. The other end of the first relay and the cathode of the third diode are connected to the eighth terminal of the timer.

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