Detection and protection circuit of temperature sampling circuit

Abstract

The utility model discloses a detection and protection circuit of a temperature sampling circuit, which belongs to the technical field of circuit detection and comprises a temperature detection module. The temperature detection module is connected with a temperature sampling module used for collecting temperature, a subtraction module used for calculating voltage on the two sides of the temperature detection module and a short circuit protection module used for protecting the short circuit condition. The temperature sampling module is connected with the short-circuit protection module, and the subtraction module is connected with the short-circuit protection module. Through the above mode, the circuit fault diagnosis is carried out without software, the fault diagnosis can be directly carried out on the circuit from the operation state of the circuit, the circuit short circuit fault can be detected, and the circuit fault diagnosis circuit has a protection function.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit detection, in particular to a detection and protection circuit of a temperature sampling circuit. Background Art

[0002] The existing temperature sampling circuit generally divides the voltage in series through a pull-up resistor and a thermistor, then collects the voltage value of the thermistor voltage divider through the AD sampling port of the microcontroller, and finally completes the temperature sampling work by calibrating the temperature value and the sampled voltage value one by one.

[0003] At present, the short-circuit detection circuit of the temperature sampling circuit basically relies on software logic judgment. If the sampling value and the VCC voltage are equal, it is judged as a short power fault, and if the sampling value and the GND voltage are equal, it is judged as a short ground fault. Therefore, the existing solutions have the following problems:

[0004] 1. Fault diagnosis relies on software, which takes up more code resources when the microcontroller resources are insufficient;

[0005] 2. Detecting short-circuit faults through sampling AD values ​​of software can only complete the detection function, but does not have a protection function.

[0006] Based on this, the utility model designs a detection and protection circuit of a temperature sampling circuit to solve the above problems. Utility Model Content

[0007] In view of the above-mentioned shortcomings of the prior art, the utility model provides a detection and protection circuit for a temperature sampling circuit.

[0008] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] A detection and protection circuit for a temperature sampling circuit, comprising a temperature detection module, wherein the temperature detection module is connected to a temperature sampling module for collecting temperature, a subtraction operation module for calculating voltages at both sides of the temperature detection module, and a short circuit protection module for protecting against short circuit conditions;

[0010] The temperature sampling module is connected to the short circuit protection module, and the subtraction module is connected to the short circuit protection module;

[0011] The temperature sampling module includes a first sampling circuit and a second sampling circuit; the first sampling circuit is connected to the temperature detection module, and the second sampling circuit is connected to both the temperature detection module and the short circuit protection module;

[0012] The short circuit protection module includes a first protection module, a second protection module and a third protection module; the first protection module is connected to the second protection module, the first protection module and the second protection module are both connected to the subtraction operation module, and the third protection module is connected to the temperature detection module and the second sampling circuit.

[0013] Furthermore, the temperature detection module includes a thermistor RX and a pull-up resistor R8.

[0014] Furthermore, the first sampling circuit includes a PMOS transistor Q1 and a resistor R19; the second sampling circuit includes an NMOS transistor Q2 and a resistor R20.

[0015] Furthermore, the subtraction operation module includes a resistor R13, a resistor R11, a resistor R6, a resistor R7 and a comparator U1A.

[0016] Furthermore, the first protection module includes a resistor R5, a comparator U2A, a resistor R1, a resistor R4 and a resistor R2;

[0017] The second protection module includes a resistor R10, a resistor R12, a resistor R14 and a comparator U2B;

[0018] The third protection module includes a resistor R16, a resistor R17, a resistor R15, a comparator U3A and a resistor R18.

[0019] Furthermore, the thermistor RX includes two ports, one end is IN+, and the other end is IN-, IN- is connected to GND, IN+ is electrically connected to one end of the pull-up resistor R8 and one end of the resistor R6, the other end of the resistor R6 is electrically connected to one end of the resistor R7 and the second port of the comparator U1A, and the other end of the resistor R7 is electrically connected to the first port of the comparator U1A, one end of the resistor R10, and one end of the resistor R5;

[0020] The other end of the pull-up resistor R8 is electrically connected to the drain of the PMOS tube Q1 and one end of the resistor R11, the source of the PMOS tube Q1 is electrically connected to VCC, the gate of the PMOS tube Q1 is electrically connected to one end of the resistor R19; the other end of the resistor R19 is electrically connected to MCU_DI_SHORT_VCC.

[0021] Furthermore, the other end of the resistor R11 is electrically connected to one end of the resistor R13 and the third port of the comparator U1A, the other end of the resistor R13 is electrically connected to GND, the fourth port of the comparator U1A is electrically connected to GND, and the fifth port of the comparator U1A is electrically connected to a 15V power supply.

[0022] Furthermore, the other end of the resistor R5 is electrically connected to the second port of the comparator U2A, the third port of the comparator U2A is electrically connected to one end of the resistor R1 and the resistor R4, the other end of the resistor R1 is electrically connected to GND, the other end of the resistor R4 is electrically connected to VCC, the first port of the comparator U2A is electrically connected to one end of the resistor R2 and MCU_DI_SHORT_VCC, the other end of the resistor R2 is electrically connected to VCC, the fourth port of the comparator U2A is electrically connected to GND, and the fifth port of the comparator U2A is electrically connected to a 15V power supply.

[0023] Furthermore, the other end of the resistor R10 is electrically connected to the second port of the comparator U2B, the third port of the comparator U2B is electrically connected to one end of the resistor R14 and one end of the resistor R12, the other end of the resistor R14 is electrically connected to GND, the other end of the resistor R12 is electrically connected to VCC, the fourth port of the comparator U2B is electrically connected to GND, the fifth port of the comparator U2B is electrically connected to a 15V power supply, and the first port of the comparator U2B is electrically connected to one end of the resistor R2 and MCU_DI_SHORT_VCC.

[0024] Furthermore, IN- of the thermistor RX is electrically connected to one end of the resistor R15 and the drain of the NMOS tube Q2, the other end of the resistor R15 is electrically connected to the second port of the comparator U3A, the third port of the comparator U3A is electrically connected to one end of the resistor R16 and one end of the resistor R17, the other end of the resistor R16 is electrically connected to VCC, the other end of the resistor R17 is electrically connected to GND, the fifth port of the comparator U3A is electrically connected to a 15V power supply, the fourth port of the comparator U3A is electrically connected to GND, the first port of the comparator U3A is electrically connected to one end of the resistor R18, one end of the resistor R20, and MCU_DI_SHORT_VCC2, the other end of the resistor R18 is electrically connected to VCC, the other end of the resistor R20 is electrically connected to the gate of the NMOS tube Q2, and the source of the NMOS tube Q2 is electrically connected to GND.

[0025] Compared with the prior art, the utility model has the following beneficial effects: 1. The circuit fault diagnosis of the utility model does not rely on software, and the circuit fault diagnosis can be performed directly based on the running state of the circuit.

[0026] 2. This utility model can not only detect circuit short circuit faults, but also has a protective function.

[0027] 3. When the utility is working normally, R8 and RX are connected in series to divide the voltage. PMOS tube Q1 and NMOS tube Q2 are normally turned on, and because the internal resistance of PMOS tube Q1 and NMOS tube Q2 is usually at the mΩ level and will not affect the voltage division of R8 and RX, the internal resistance of PMOS tube Q1 and NMOS tube Q2 is not counted. The single-chip microcomputer can directly read the voltage of IN+ to GND to complete the temperature sampling work. R19 and R20 are the driving resistors of PMOS tube Q1 and NMOS tube Q2 to prevent oscillation when PMOS tube Q1 and NMOS tube Q2 are switched.

[0028] IN+ and the positive power supply short circuit detection and protection: The subtractor composed of resistors R13, R11, R6, R7, and comparator U1A performs subtraction operation on the voltage across resistor R8 (VO1=Va-IN+). When IN+ and the positive power supply VCC are short-circuited, the voltages of Va and IN+ are equal, and VO1 outputs 0V. The reference voltage of the second terminal of comparator U2A is 0.2V, and the input voltage of the in-phase terminal is equal to VO1, which is 0V. The first terminal of comparator U2A outputs a high level to report the IN+ short power fault to the microcontroller, and at the same time, the PMOS tube Q1 is turned off to prevent the external power supply from affecting the internal power supply.

[0029] IN+ and power supply GND short circuit detection and protection: The subtractor composed of resistor R13, resistor R11, resistor R6, resistor R7, and comparator U1A performs subtraction operation on the voltage across R8 (VO1=Va-IN+). When IN+ and power supply GND are short-circuited, IN+ is 0V, Va is 5V, and the subtractor output VO1 is 5V. The input voltage at the second end of comparator U2B is equal to VO1, which is 0V, and the reference voltage at the in-phase end is 4.8V. The first output end of comparator U2B outputs a low level to report the short circuit fault of IN+ and power supply GND to the microcontroller, and at the same time turns off the PMOS tube Q1 to prevent the short-circuit current from being too large and damaging resistor R8.

[0030] IN- and the positive power supply short circuit detection and protection: The second end of the comparator U3A is directly connected to IN-, and the in-phase end obtains a 4.8V reference voltage through resistors R16 and R15. During normal operation, R18 is pulled up to 5V to turn on the NMOS tube Q2, the voltage connected to IN-Q2 and GND is 0V, and the first output end of the comparator U3A outputs a high level. When IN- and the positive power supply are short-circuited, the IN+ voltage is 5V and greater than the reference voltage, and the first output end of the comparator U3A outputs a low level to report a short circuit fault between IN- and the positive power supply, and at the same time turns off the NMOS tube Q2 to prevent the power supply from being short-circuited to GND. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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 prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 The utility model is a frame of a detection and protection circuit of a temperature sampling circuit Figure 1 ;

[0033] Figure 2 The utility model is a frame of a detection and protection circuit of a temperature sampling circuit Figure 2 ;

[0034] Figure 3 The utility model is a circuit connection diagram of a detection and protection circuit of a temperature sampling circuit.

[0035] The numbers in the figure represent:

[0036] 1. Temperature detection module; 2. Temperature sampling module; 21. First sampling circuit; 22. Second sampling circuit; 3. Subtraction operation module; 4. Short circuit protection module; 41. First protection module; 42. Second protection module; 43. Third protection module. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment 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.

[0038] Embodiment 1: In some embodiments, please refer to the drawings of the specification Figure 1-Figure 3 , a detection and protection circuit of a temperature sampling circuit, comprising a temperature detection module 1, wherein the temperature detection module 1 is connected to a temperature sampling module 2 for collecting temperature, a subtraction operation module 3 for calculating voltages on both sides of the temperature detection module 1, and a short-circuit protection module 4 for protecting against short-circuit conditions;

[0039] The temperature sampling module 2 is connected to the short circuit protection module 4, and the subtraction module 3 is connected to the short circuit protection module 4;

[0040] The temperature sampling module 2 includes a first sampling circuit 21 and a second sampling circuit 22; the first sampling circuit 21 is connected to the temperature detection module 1, and the second sampling circuit 22 is connected to both the temperature detection module 1 and the short circuit protection module 4;

[0041] The short circuit protection module 4 includes a first protection module 41, a second protection module 42 and a third protection module 43; the first protection module 41 is connected to the second protection module 42, the first protection module 41 and the second protection module 42 are both connected to the subtraction module 3, and the third protection module 43 is connected to the temperature detection module 1 and the second sampling circuit 22.

[0042] The temperature detection module 1 includes a thermistor RX and a pull-up resistor R8;

[0043] The temperature sampling module 2 includes a first sampling circuit 21 and a second sampling circuit 22 ; the first sampling circuit 21 is connected to the other end of the pull-up resistor R8 , and the second sampling circuit 22 is connected to both the thermistor RX and the short-circuit protection module 4 .

[0044] The first sampling circuit 21 includes a PMOS (positive channel Metal Oxide Semiconductor) tube Q1 and a resistor R19; the second sampling circuit 22 includes an NMOS (Negative channel-Metal-Oxide-Semiconductor, N-type Metal Oxide Semiconductor) tube Q2 and a resistor R20;

[0045] The subtraction operation module 3 includes a resistor R13, a resistor R11, a resistor R6, a resistor R7 and a comparator U1A;

[0046] The short circuit protection module 4 includes a first protection module 41, a second protection module 42 and a third protection module 43; the first protection module 41 is connected to the second protection module 42, the first protection module 41 and the second protection module 42 are both connected to the subtraction module 3, and the third protection module 43 is connected to the thermistor RX and the second sampling circuit 22.

[0047] The first protection module 41 includes a resistor R5, a comparator U2A, a resistor R1, a resistor R4 and a resistor R2;

[0048] The second protection module 42 includes a resistor R10, a resistor R12, a resistor R14 and a comparator U2B;

[0049] The third protection module 43 includes a resistor R16 , a resistor R17 , a resistor R15 , a comparator U3A and a resistor R18 .

[0050] The thermistor RX includes two ports, one end is IN+ (positive input of data signal) and the other end is IN- (negative input of data signal);

[0051] There are four possible short circuit situations:

[0052] IN+ and the positive pole of the power supply are short-circuited, IN+ and the power supply GND (Ground terminal) are short-circuited, IN- and the positive pole of the power supply are short-circuited, and IN- and the power supply GND are short-circuited.

[0053] Among them, the fourth situation where IN- and power supply GND are short-circuited will not affect temperature sampling, so short-circuit protection is not performed.

[0054] like Figure 3 As shown, IN- is connected to GND, IN+ is electrically connected to one end of the pull-up resistor R8 and one end of the resistor R6, the other end of the resistor R6 is electrically connected to one end of the resistor R7 and the second port of the comparator U1A, and the other end of the resistor R7 is electrically connected to the first port of the comparator U1A, one end of the resistor R10, and one end of the resistor R5;

[0055] The other end of the pull-up resistor R8 is electrically connected to the drain of the PMOS tube Q1 and one end of the resistor R11, the source of the PMOS tube Q1 is electrically connected to VCC (Volt Current Condenser supply voltage), the gate of the PMOS tube Q1 is electrically connected to one end of the resistor R19; the other end of the resistor R19 is electrically connected to MCU_DI_SHORT_VCC.

[0056] The other end of resistor R11 is electrically connected to one end of resistor R13 and the third port of comparator U1A. The other end of resistor R13 is electrically connected to GND. The fourth port of comparator U1A is electrically connected to GND. The fifth port of comparator U1A is electrically connected to a 15V power supply.

[0057] The other end of resistor R5 is electrically connected to the second port of comparator U2A, the third port of comparator U2A is electrically connected to one end of resistor R1 and resistor R4, the other end of resistor R1 is electrically connected to GND, the other end of resistor R4 is electrically connected to VCC, the first port of comparator U2A is electrically connected to one end of resistor R2 and MCU_DI_SHORT_VCC (first power supply interface of microcontroller), the other end of resistor R2 is electrically connected to VCC, the fourth port of comparator U2A is electrically connected to GND, and the fifth port of comparator U2A is electrically connected to a 15V power supply.

[0058] The other end of resistor R10 is electrically connected to the second port of comparator U2B, the third port of comparator U2B is electrically connected to one end of resistor R14 and one end of resistor R12, the other end of resistor R14 is electrically connected to GND, the other end of resistor R12 is electrically connected to VCC, the fourth port of comparator U2B is electrically connected to GND, the fifth port of comparator U2B is electrically connected to a 15V power supply, and the first port of comparator U2B is electrically connected to one end of resistor R2 and MCU_DI_SHORT_VCC.

[0059] IN- of the thermistor RX is electrically connected to one end of the resistor R15 and the drain of the NMOS tube, the other end of the resistor R15 is electrically connected to the second port of the comparator U3A, the third port of the comparator U3A is electrically connected to one end of the resistor R16 and one end of the resistor R17, the other end of the resistor R16 is electrically connected to VCC, the other end of the resistor R17 is electrically connected to GND, the fifth port of the comparator U3A is electrically connected to a 15V power supply, the fourth port of the comparator U3A is electrically connected to GND, the first port of the comparator U3A is electrically connected to one end of the resistor R18, one end of the resistor R20, and MCU_DI_SHORT_VCC2 (the second power supply interface of the single-chip computer), the other end of the resistor R18 is electrically connected to VCC, the other end of the resistor R20 is electrically connected to the gate of the NMOS tube Q2, and the source of the NMOS tube Q2 is electrically connected to GND.

[0060] When the utility model works normally, R8 and RX are connected in series to divide the voltage. PMOS tube Q1 and NMOS tube Q2 are normally turned on, and since the internal resistance of PMOS tube Q1 and NMOS tube Q2 is usually at the mΩ level and will not affect the voltage division of R8 and RX, the internal resistance of PMOS tube Q1 and NMOS tube Q2 is not counted. The single chip microcomputer can directly read the voltage of IN+ to GND to complete the temperature sampling work. R19 and R20 are the driving resistors of PMOS tube Q1 and NMOS tube Q2 to prevent oscillation when PMOS tube Q1 and NMOS tube Q2 are switched.

[0061] IN+ and the positive power supply short circuit detection and protection: The subtractor composed of resistors R13, R11, R6, R7, and comparator U1A performs subtraction operation on the voltage across resistor R8 (VO1=Va-IN+). When IN+ and the positive power supply VCC are short-circuited, the voltages of Va and IN+ are equal, and VO1 outputs 0V. The reference voltage of the second terminal of comparator U2A is 0.2V, and the input voltage of the in-phase terminal is equal to VO1, which is 0V. The first terminal MCU_DI_SHORT_VCC of comparator U2A outputs a high level to report the IN+ short power fault to the microcontroller, and at the same time, the PMOS tube Q1 is turned off to prevent the external power supply from affecting the internal power supply.

[0062] IN+ and power supply GND short circuit detection and protection: The subtractor composed of resistor R13, resistor R11, resistor R6, resistor R7, and comparator U1A performs subtraction operation on the voltage across R8 (VO1=Va-IN+). When IN+ and power supply GND are short-circuited, IN+ is 0V, Va is 5V, and the subtractor output VO1 is 5V. The input voltage of the second terminal of comparator U2B is equal to VO1, which is 0V, and the reference voltage of the in-phase terminal is 4.8V. The first terminal MCU_DI_SHORT_VCC of comparator U2B outputs a low level to report the short circuit fault of IN+ and power supply GND to the microcontroller, and at the same time turns off the PMOS tube Q1 to prevent the short-circuit current from being too large and damaging resistor R8.

[0063] IN- and the positive power supply short circuit detection and protection: The second end of the comparator U3A is directly connected to IN-, and the in-phase end obtains a 4.8V reference voltage through resistors R16 and R15. During normal operation, R18 is pulled up to 5V to turn on the NMOS tube Q2, the voltage connected between IN-Q2 and GND is 0V, and the first end MCU_DI_SHORT_VCC2 of the comparator U3A outputs a high level. When IN- and the positive power supply are short-circuited, the IN+ voltage is 5V and greater than the reference voltage, and the first output end of the comparator U3A outputs a low level to report a short circuit fault between IN- and the positive power supply, and at the same time turns off the NMOS tube Q2 to prevent the power supply from being short-circuited to GND.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A detection and protection circuit for a temperature sampling circuit, characterized in that: The temperature detection module (1) is connected to a temperature sampling module (2) for collecting temperature, a subtraction operation module (3) for calculating voltages at both sides of the temperature detection module (1), and a short-circuit protection module (4) for protecting against short-circuit conditions; The temperature sampling module (2) is connected to the short-circuit protection module (4), and the subtraction operation module (3) is connected to the short-circuit protection module (4); The temperature sampling module (2) comprises a first sampling circuit (21) and a second sampling circuit (22); the first sampling circuit (21) is connected to the temperature detection module (1), and the second sampling circuit (22) is connected to both the temperature detection module (1) and the short-circuit protection module (4); The short circuit protection module (4) comprises a first protection module (41), a second protection module (42) and a third protection module (43); the first protection module (41) is connected to the second protection module (42), the first protection module (41) and the second protection module (42) are both connected to the subtraction operation module (3), and the third protection module (43) is both connected to the temperature detection module (1) and the second sampling circuit (22).

2. The detection and protection circuit of the temperature sampling circuit according to claim 1, characterized in that: The temperature detection module (1) comprises a thermistor RX and a pull-up resistor R8.

3. The detection and protection circuit of the temperature sampling circuit according to claim 2, characterized in that: The first sampling circuit (21) comprises a PMOS transistor Q1 and a resistor R19; the second sampling circuit (22) comprises an NMOS transistor Q2 and a resistor R20.

4. The detection and protection circuit of the temperature sampling circuit according to claim 3, characterized in that: The subtraction operation module (3) comprises a resistor R13, a resistor R11, a resistor R6, a resistor R7 and a comparator U1A.

5. The detection and protection circuit of the temperature sampling circuit according to claim 4, characterized in that: The first protection module (41) comprises a resistor R5, a comparator U2A, a resistor R1, a resistor R4 and a resistor R2; The second protection module (42) comprises a resistor R10, a resistor R12, a resistor R14 and a comparator U2B; The third protection module (43) comprises a resistor R16, a resistor R17, a resistor R15, a comparator U3A and a resistor R18.

6. The detection and protection circuit of the temperature sampling circuit according to claim 5, characterized in that: The thermistor RX includes two ports, one end is IN+, and the other end is IN-, IN- is connected to GND, IN+ is electrically connected to one end of the pull-up resistor R8 and one end of the resistor R6, the other end of the resistor R6 is electrically connected to one end of the resistor R7 and the second port of the comparator U1A, and the other end of the resistor R7 is electrically connected to the first port of the comparator U1A, one end of the resistor R10, and one end of the resistor R5; The other end of the pull-up resistor R8 is electrically connected to the drain of the PMOS tube Q1 and one end of the resistor R11, the source of the PMOS tube Q1 is electrically connected to VCC, the gate of the PMOS tube Q1 is electrically connected to one end of the resistor R19; the other end of the resistor R19 is electrically connected to MCU_DI_SHORT_VCC.

7. The detection and protection circuit of the temperature sampling circuit according to claim 6, characterized in that: The other end of resistor R11 is electrically connected to one end of resistor R13 and the third port of comparator U1A. The other end of resistor R13 is electrically connected to GND. The fourth port of comparator U1A is electrically connected to GND. The fifth port of comparator U1A is electrically connected to a 15V power supply.

8. The detection and protection circuit of the temperature sampling circuit according to claim 7, characterized in that: The other end of resistor R5 is electrically connected to the second port of comparator U2A, the third port of comparator U2A is electrically connected to one end of resistor R1 and resistor R4, the other end of resistor R1 is electrically connected to GND, the other end of resistor R4 is electrically connected to VCC, the first port of comparator U2A is electrically connected to one end of resistor R2 and MCU_DI_SHORT_VCC, the other end of resistor R2 is electrically connected to VCC, the fourth port of comparator U2A is electrically connected to GND, and the fifth port of comparator U2A is electrically connected to a 15V power supply.

9. The detection and protection circuit of the temperature sampling circuit according to claim 8, characterized in that: The other end of resistor R10 is electrically connected to the second port of comparator U2B, the third port of comparator U2B is electrically connected to one end of resistor R14 and one end of resistor R12, the other end of resistor R14 is electrically connected to GND, the other end of resistor R12 is electrically connected to VCC, the fourth port of comparator U2B is electrically connected to GND, the fifth port of comparator U2B is electrically connected to a 15V power supply, and the first port of comparator U2B is electrically connected to one end of resistor R2 and MCU_DI_SHORT_VCC.

10. The detection and protection circuit of the temperature sampling circuit according to claim 9, characterized in that: IN- of thermistor RX is electrically connected to one end of resistor R15 and the drain of NMOS tube Q2, the other end of resistor R15 is electrically connected to the second port of comparator U3A, the third port of comparator U3A is electrically connected to one end of resistor R16 and one end of resistor R17, the other end of resistor R16 is electrically connected to VCC, the other end of resistor R17 is electrically connected to GND, the fifth port of comparator U3A is electrically connected to a 15V power supply, the fourth port of comparator U3A is electrically connected to GND, the first port of comparator U3A is electrically connected to one end of resistor R18, one end of resistor R20, and MCU_DI_SHORT_VCC2, the other end of resistor R18 is electrically connected to VCC, the other end of resistor R20 is electrically connected to the gate of NMOS tube Q2, and the source of NMOS tube Q2 is electrically connected to GND.

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