Program-controlled resistive load circuit

Abstract

The utility model relates to the technical field of circuits, in particular to a program-controlled resistive load circuit, which comprises a power supply module, an optical coupler isolation module, a serial-parallel conversion module, a single chip microcomputer U5 and an adjusting resistance module, and is characterized in that the adjusting resistance module comprises a first adjusting resistance circuit and a second adjusting resistance circuit; according to the utility model, the single-chip microcomputer is used for controlling the level of the pins so as to control the on / off of the MOS tubes of the second resistor circuit, so that different stable resistors are generated, and meanwhile, each MOS tube can be independently controlled, so that the generated resistance value is more accurate, and the adjustment range is wider. In order to consider that the MOS tubes have internal resistance, and when a plurality of MOS tubes are connected in series, a certain influence is generated on the generated resistance value, the first resistance circuit is designed, and the first resistance circuit adopts one MOS tube to replace a plurality of MOS tubes of the second resistance circuit, so that the influence caused by the internal resistance of the plurality of MOS tubes is reduced.

Description

Technical Field

[0001] This utility model relates to the field of circuit technology, and more specifically, to a programmable resistive load circuit. Background Technology

[0002] In electronics and electrical engineering, resistance boxes are commonly used for precise measurement of resistance values ​​and for fine-tuning resistance. The principle of a resistance box is to combine multiple fixed resistive elements together, changing the overall resistance value by altering the connection method of these elements. By rotating or adjusting the controller of the resistance box, the connection relationship between the elements can be changed, thus achieving continuous adjustment of the resistance value. However, some adjustable load resistance circuits have appeared on the market. Compared to resistance boxes, these adjustable load resistance circuits use microcontroller control, offering greater precision and stability.

[0003] For example, a numerically controlled variable resistor circuit (publication number: CN213874737U, publication date: 2021-08-03) includes a power supply VCC, a voltage regulator LDO, an NTC analog port P1, capacitors T1 and T2, a microcontroller MCU, a resistor R1, and a four-channel variable resistor module. The positive input terminal IN+ of the NTC analog port P1 is connected to the ground signal GND. The power supply VCC is connected to pin 3 of the voltage regulator LDO. Pin 2 of the voltage regulator LDO is connected to one end of capacitor T1 through resistor R1. The other end of capacitor T1 is connected to the ground signal GND. The other end of capacitor T1 is also connected to the microcontroller MCU. Capacitor T1 and capacitor T2 are connected in parallel. One end of capacitor T1 is connected to the microcontroller MCU.

[0004] This circuit controls the level of the C1 to C40 terminals through a microcontroller (MCU) to control the MOSFET's on or off state, thereby generating different resistance values ​​and automating the simulated temperature test of the protection board. However, this circuit does not take into account the internal resistance of the MOSFET. When multiple MOSFETs are connected in series, it will have a certain impact on the generated resistance value. Utility Model Content

[0005] To address the technical deficiencies in the background technology, this utility model proposes a programmable resistive load circuit, which solves the aforementioned technical problems and meets practical needs. The specific technical solution is as follows:

[0006] A programmable resistive load circuit includes: a power supply module, an optocoupler isolation module, a serial-to-parallel conversion module, a microcontroller U5, and an adjustable resistor module. The power supply module outputs power to the optocoupler isolation module, the serial-to-parallel conversion module, the microcontroller U5, and the adjustable resistor module. The optocoupler isolation module and the serial-to-parallel conversion module are electrically connected to the microcontroller U5, and the serial-to-parallel conversion module and the microcontroller U5 are electrically connected to the adjustable resistor module.

[0007] The serial-to-parallel conversion module includes two parallel registers, register U6 and register U7, and the adjusting resistor module includes a first adjusting resistor circuit and a second adjusting resistor circuit. The microcontroller U5 is electrically connected to the first adjusting resistor circuit, and the output terminals of the two registers are electrically connected to the second adjusting resistor circuit.

[0008] The first regulating resistor circuit includes several first load branches composed of a first MOSFET, a second MOSFET, and a first resistor. The second MOSFET in each first load branch is connected in parallel with the first resistor and then in series with the first switching transistor. The second regulating resistor circuit includes several second load branches composed of several third MOSFETs and several second resistors. The several second resistors are connected in series, and each second resistor is connected in parallel with a third MOSFET. The two ends of each second MOSFET are connected in parallel to the branches in series with multiple second resistors.

[0009] As a further technical solution of this utility model, the power supply module includes an isolated power supply module and a voltage regulator U3, and the power supply module is provided with a 9V output voltage and a 5V output voltage.

[0010] As a further technical solution of this utility model, the optocoupler isolation module includes an optocoupler U1 and an optocoupler U2. The pin 6 of the optocoupler U1 is electrically connected to the pin 1 of the microcontroller U5, and the pin 3 of the optocoupler U2 is electrically connected to the pin 2 of the microcontroller U5.

[0011] As a further technical solution of this utility model, the serial-to-parallel conversion module includes MOSFETs Q23, Q26, Q29, and Q31. Pin 3 of the microcontroller U5 is electrically connected to the gate of MOSFET Q23. The drain of MOSFET Q23 is connected to pin 1 of the two registers via a parallel resistor R23. Pin 19 of the microcontroller U5 is electrically connected to the gate of MOSFET Q26. The drain of MOSFET Q26 is connected to pin 2 of register U6 via a parallel resistor R27. Pin 18 of the microcontroller U5 is electrically connected to the gate of MOSFET Q29. The drain of MOSFET Q29 is connected to pin 3 of the two registers via a parallel resistor R29. Pin 17 of the microcontroller U5 is electrically connected to the gate of MOSFET Q31. The drain of MOSFET Q31 is connected to pin 15 of the two registers via a parallel resistor R31.

[0012] As a further technical solution of this utility model, the first load branch is provided with five lines, and the pins 12-16 of the microcontroller U5 are electrically connected to the five first load branches respectively. The first MOSFET includes MOSFET Q24, MOSFET Q19, MOSFET Q15, MOSFET Q12 and MOSFET Q8. The second MOSFET includes MOSFET Q21, MOSFET Q18, MOSFET Q14, MOSFET Q10 and MOSFET Q6. The first resistor includes resistor R24, resistor R20, resistor R17, resistor R15 and resistor R12.

[0013] As a further technical solution of this utility model, pin 12 of the microcontroller U5 is electrically connected to the gate of MOSFET Q24, and the drain of MOSFET Q24 is connected to the gate of MOSFET Q21 after a parallel resistor R24 ​​is connected; pin 13 of the microcontroller U5 is electrically connected to the gate of MOSFET Q19, and the drain of MOSFET Q19 is connected to the gate of MOSFET Q18 after a parallel resistor R20 is connected; pin 14 of the microcontroller U5 is electrically connected to the gate of MOSFET Q15, and the drain of MOSFET Q25 is connected to the gate of MOSFET Q14 after a parallel resistor R17 is connected; pin 15 of the microcontroller U5 is electrically connected to the gate of MOSFET Q12, and the drain of MOSFET Q12 is connected to the gate of MOSFET Q10 after a parallel resistor R15 is connected; pin 16 of the microcontroller U5 is electrically connected to the gate of MOSFET Q8, and the drain of MOSFET Q8 is connected to the gate of MOSFET Q6 after a parallel resistor R12 is connected.

[0014] As a further technical solution of this utility model, the second resistor includes resistors R1-R16, and the third MOSFET includes MOSFETs Q1-Q5, Q7, Q9, Q11, Q13, Q16-Q17, Q20, Q22, Q25, Q27-Q28, and Q30. The gate of each of the third MOSFETs is connected to ground after a resistor is connected in parallel.

[0015] As a further technical solution of this utility model, the second resistors R1-R16 are connected in series, the resistor R1 is connected in series with the third MOSFET Q30, pin 11 of the microcontroller U5 is electrically connected to the gate of the MOSFET Q30, pin 4 of the register U6 is electrically connected to the gate of the MOSFET Q28 and then connected in parallel with resistor R1; pin 5 of the register U6 is electrically connected to the gate of the MOSFET Q27 and then connected in parallel with resistor R2; pin 6 of the register U6 is electrically connected to the gate of the MOSFET Q25 and then connected in parallel with resistor R2. R3; Pin 7 of register U6 is electrically connected to the gate of MOSFET Q22 and then connected in parallel with resistor R4; Pin 14 of register U6 is electrically connected to the gate of MOSFET Q20 and then connected in parallel with resistor R5; Pin 13 of register U6 is electrically connected to the gate of MOSFET Q17 and then connected in parallel with resistor R6; Pin 12 of register U6 is electrically connected to the gate of MOSFET Q16 and then connected in parallel with resistor R7; Pin 11 of register U6 is electrically connected to the gate of MOSFET Q13 and then connected in parallel with resistor R8.

[0016] As a further technical solution of this utility model, pin 11 of the microcontroller U5 is electrically connected to the gate of MOSFET Q30; pin 4 of the register U7 is electrically connected to the gate of MOSFET Q11 and then connected in parallel with resistor R9; pin 5 of the register U7 is electrically connected to the gate of MOSFET Q9 and then connected in parallel with resistor R10; pin 6 of the register U7 is electrically connected to the gate of MOSFET Q7 and then connected in parallel with resistor R11; pin 7 of the register U7 is electrically connected to the gate of MOSFET Q5 and then connected in parallel with resistor R12; pin 14 of the register U7 is electrically connected to the gate of MOSFET Q3 and then connected in parallel with resistor R13; pin 13 of the register U7 is electrically connected to the gate of MOSFET Q1 and then connected in parallel with resistor R14; pin 12 of the register U7 is electrically connected to the gate of MOSFET Q4 and then connected in parallel with resistor R15; and pin 11 of the register U7 is electrically connected to the gate of MOSFET Q2 and then connected in parallel with resistor R16.

[0017] As a further technical solution of this utility model, the drain of MOSFET Q21 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q21 is electrically connected to the source of MOSFET Q28; the drain of MOSFET Q18 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q18 is electrically connected to the source of MOSFET Q25; the drain of MOSFET Q14 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q14 is electrically connected to the source of MOSFET Q20; the drain of MOSFET Q10 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q10 is electrically connected to the source of MOSFET Q16; the drain of MOSFET Q6 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q6 is electrically connected to the source of MOSFET Q7.

[0018] The beneficial effects of this utility model are as follows:

[0019] This invention controls the level of the pins of a microcontroller to control the on or off state of the MOSFET in the second resistor circuit, thereby generating different stable resistances. Each MOSFET can be controlled independently. When a MOSFET is turned on, the resistor connected in parallel with that MOSFET is short-circuited, resulting in more accurate resistance values ​​and a wider adjustment range.

[0020] To account for the internal resistance of MOSFETs, which can affect the generated resistance when multiple MOSFETs are connected in series, this invention designs a first resistor circuit. The first resistor circuit replaces multiple MOSFETs in the second resistor circuit with a single MOSFET, thereby reducing the impact of the internal resistance of multiple MOSFETs. Attached Figure Description

[0021] Figure 1 This is a topology diagram of a programmable resistive load circuit.

[0022] Figure 2 This is a power supply module topology diagram for a programmable resistive load circuit.

[0023] Figure 3 This is a topology diagram of an optocoupler isolation module for a programmable resistive load circuit.

[0024] Figure 4 This is a topology diagram of a serial-to-parallel conversion module for a programmable resistive load circuit.

[0025] Figure 5 This is a topology diagram of a microcontroller U5 for a programmable resistive load circuit.

[0026] Figure 6 This is a topology diagram of an adjustable resistor module for a programmable resistive load circuit.

[0027] The components include: power supply module 1, optocoupler isolation module 2, serial-to-parallel conversion module 3, adjustable resistor module 4, first adjustable resistor circuit 41, and second adjustable resistor circuit 42. Detailed Implementation

[0028] The following is in conjunction with the appendix Figures 1-6 The embodiments of this utility model are described in conjunction with related examples. However, the embodiments of this utility model are not limited to those described below. Furthermore, this utility model relates to necessary components in this technical field and should be considered as well-known technology in this technical field, which can be known and mastered by those skilled in the art.

[0029] This utility model provides a programmable resistive load circuit, such as Figure 1As shown, it includes a power supply module 1, an optocoupler isolation module 2, a serial-to-parallel conversion module 3, a microcontroller U5, and an adjustable resistor module 4. The output of the power supply module 1 supplies power to the optocoupler isolation module 2, the serial-to-parallel conversion module 3, the microcontroller U5, and the adjustable resistor module 4. The optocoupler isolation module 2 and the serial-to-parallel conversion module 3 are electrically connected to the microcontroller U5, and the serial-to-parallel conversion module 3 and the microcontroller U5 are electrically connected to the adjustable resistor module 4.

[0030] like Figure 4 As shown, the serial-to-parallel conversion module 3 includes two parallel registers, register U6 and register U7, as follows: Figure 6 As shown, the adjustable resistor module 4 includes a first adjustable resistor circuit 41 and a second adjustable resistor circuit 42. The microcontroller U5 is electrically connected to the first adjustable resistor circuit 41, and the output terminals of the two registers are electrically connected to the second adjustable resistor circuit 42. The first adjustable resistor circuit 41 includes several first load branches composed of a first MOSFET, a second MOSFET, and a first resistor. The second MOSFET of each first load branch is connected in parallel with the first resistor and then in series with the first switching transistor. The second adjustable resistor circuit 42 includes several second load branches composed of several third MOSFETs and several second resistors. The several second resistors are connected in series, and each second resistor is connected in parallel with a third MOSFET. The two ends of each second MOSFET are connected in parallel to the branches in series with multiple second resistors.

[0031] In this invention, the electrical connection is achieved through a wire.

[0032] This invention uses the level of a microcontroller control pin to control the on / off state of the MOSFETs in the second resistor circuit, thereby generating different stable resistances. Each MOSFET can be controlled independently; when one MOSFET is turned on, the resistor connected in parallel with that MOSFET is short-circuited, resulting in more accurate resistance values ​​and a wider adjustment range. To address the issue of internal resistance in MOSFETs, which can affect the generated resistance when multiple MOSFETs are connected in series, this invention designs a first resistor circuit. This first resistor circuit uses a single MOSFET to replace multiple MOSFETs in the second resistor circuit, thus reducing the impact of the internal resistance of multiple MOSFETs.

[0033] As one of the preferred embodiments of this utility model, such as Figure 2 As shown, the power supply module 1 includes an isolation power supply module and a voltage regulator U3. The power supply module 1 has a 9V output voltage to supply registers U6 and U7, the first regulating resistor circuit 41 and the second regulating resistor circuit 42. At the same time, the isolation power supply module plays a further electrical isolation role. The transmission and isolation of power energy are realized through the isolation power supply module. The power supply module 1 outputs a 5V output voltage through the voltage regulator U3 and supplies power to the optocoupler isolation module 2 and the microcontroller U5.

[0034] As one of the preferred embodiments of this utility model, such as Figure 3 As shown, the optocoupler isolation module 2 includes optocoupler U1 and optocoupler U2. Pin 6 of optocoupler U1 is electrically connected to pin 1 of microcontroller U5, and pin 3 of optocoupler U2 is electrically connected to pin 2 of microcontroller U5. The optocoupler isolation module 2 achieves electrical isolation between the input and output circuits, thereby avoiding direct electrical contact between circuits and improving the circuit's anti-interference capability and safety. Furthermore, since the input terminal of the optocoupler is a current-driven low-resistance element, it also has strong common-mode rejection capability, which can significantly improve the signal-to-noise ratio in long-distance transmission. In this embodiment, optocouplers U1 and U2 electrically isolate the microcontroller U5 from the external system for bidirectional communication, improving the circuit's anti-interference capability and safety.

[0035] As one of the preferred embodiments of this utility model, such as Figure 4 As shown, the serial-to-parallel conversion module 3 includes MOSFETs Q23, Q26, Q29, and Q31. Pin 3 of the microcontroller U5 is electrically connected to the gate of MOSFET Q23. The drain of MOSFET Q23 is connected to pin 1 of the two registers via a parallel resistor R23. Pin 19 of the microcontroller U5 is electrically connected to the gate of MOSFET Q26. The drain of MOSFET Q26 is connected to pin 2 of register U6 via a parallel resistor R27. Pin 18 of the microcontroller U5 is electrically connected to the gate of MOSFET Q29. The drain of MOSFET Q29 is connected to pin 3 of the two registers via a parallel resistor R29. Pin 17 of the microcontroller U5 is electrically connected to the gate of MOSFET Q31. The drain of MOSFET Q31 is connected to pin 15 of the two registers via a parallel resistor R31.

[0036] In this embodiment, registers U6 and U7 are connected in parallel to form a serial-input, parallel-output shift register. This serial-to-parallel shift register has multiple storage units, each capable of storing one binary digit. When a string of binary data is input, a clock signal sequentially shifts each data bit into the least significant bit of the register. Once all data bits have been shifted in, the data can be simultaneously output to multiple receivers via parallel output. In this embodiment, the single motor U5 supplies signal registers U6 and U7, allowing the level signal to be output in parallel to the second resistor circuit, simultaneously controlling the third MOSFET.

[0037] As one of the preferred embodiments of this utility model, the first load branch is provided with five lines, and pins 12-16 of the microcontroller U5 are electrically connected to the five first load branches respectively. The first MOSFETs include MOSFETs Q24, Q19, Q15, Q12 and Q8. The second MOSFETs include MOSFETs Q21, Q18, Q14, Q10 and Q6. The first resistors include resistors R24, R20, R17, R15 and R12.

[0038] Pin 12 of microcontroller U5 is electrically connected to the gate of MOSFET Q24. The drain of MOSFET Q24, connected in parallel with resistor R24, is then electrically connected to the gate of MOSFET Q21. Pin 13 of microcontroller U5 is electrically connected to the gate of MOSFET Q19. The drain of MOSFET Q19, connected in parallel with resistor R20, is then electrically connected to the gate of MOSFET Q18. Pin 14 of microcontroller U5 is electrically connected to the gate of MOSFET Q15. The drain of MOSFET Q25, connected in parallel with resistor R17, is then electrically connected to the gate of MOSFET Q14. Pin 15 of microcontroller U5 is electrically connected to the gate of MOSFET Q12. The drain of MOSFET Q12, connected in parallel with resistor R15, is then electrically connected to the gate of MOSFET Q10. Pin 16 of microcontroller U5 is electrically connected to the gate of MOSFET Q8. The drain of MOSFET Q8, connected in parallel with resistor R12, is then electrically connected to the gate of MOSFET Q6.

[0039] In this embodiment, the 9V output voltage is connected to the gate of the second MOSFET after being connected in series with a resistor. The pins of the microcontroller U5 control the first MOSFET through high and low levels, thereby controlling the switching of the second MOSFET. Using the first MOSFET to control the second MOSFET can change the level of the first load branch, making it convenient for the microcontroller U5 to control the first MOSFET.

[0040] In one of the preferred embodiments of this utility model, the second resistor includes resistors R1-R16, and the third MOSFET includes MOSFETs Q1-Q5, Q7, Q9, Q11, Q13, Q16-Q17, Q20, Q22, Q25, Q27-Q28, and Q30. The gate of each third MOSFET is connected to ground after a resistor is connected in parallel.

[0041] like Figure 5 and Figure 6As shown, the second resistors R1-R16 are connected in series, and resistor R1 is connected in series with the third MOSFET Q30. Pin 11 of microcontroller U5 is electrically connected to the gate of MOSFET Q30. Pin 4 of register U6 is electrically connected to the gate of MOSFET Q28 and then connected in parallel with resistor R1; pin 5 of register U6 is electrically connected to the gate of MOSFET Q27 and then connected in parallel with resistor R2; pin 6 of register U6 is electrically connected to the gate of MOSFET Q25 and then connected in parallel with resistor R3; pin 7 of register U6 is electrically connected to the gate of MOSFET Q22 and then connected in parallel with resistor R4; pin 14 of register U6 is electrically connected to the gate of MOSFET Q20 and then connected in parallel with resistor R5; pin 13 of register U6 is electrically connected to the gate of MOSFET Q17 and then connected in parallel with resistor R6; pin 12 of register U6 is electrically connected to the gate of MOSFET Q16 and then connected in parallel with resistor R7; pin 11 of register U6 is electrically connected to the gate of MOSFET Q13 and then connected in parallel with resistor R8.

[0042] Pin 11 of microcontroller U5 is electrically connected to the gate of MOSFET Q30. Pin 4 of register U7 is electrically connected to the gate of MOSFET Q11, with resistor R9 connected in parallel. Pin 5 of register U7 is electrically connected to the gate of MOSFET Q9, with resistor R10 connected in parallel. Pin 6 of register U7 is electrically connected to the gate of MOSFET Q7, with resistor R11 connected in parallel. Pin 7 of register U7 is electrically connected to the gate of MOSFET Q5, with resistor R12 connected in parallel. Pin 14 of register U7 is electrically connected to the gate of MOSFET Q3, with resistor R13 connected in parallel. Pin 13 of register U7 is electrically connected to the gate of MOSFET Q1, with resistor R14 connected in parallel. Pin 12 of register U7 is electrically connected to the gate of MOSFET Q4, with resistor R15 connected in parallel. Pin 11 of register U7 is electrically connected to the gate of MOSFET Q2, with resistor R16 connected in parallel.

[0043] In one preferred embodiment of this utility model, the drain of MOSFET Q21 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q21 is electrically connected to the source of MOSFET Q28; the drain of MOSFET Q18 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q18 is electrically connected to the source of MOSFET Q25; the drain of MOSFET Q14 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q14 is electrically connected to the source of MOSFET Q20; the drain of MOSFET Q10 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q10 is electrically connected to the source of MOSFET Q16; the drain of MOSFET Q6 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q6 is electrically connected to the source of MOSFET Q7.

[0044] In summary, the working principle of this invention is as follows: the entire load resistor is connected in series, and each second resistor is connected in parallel with a third MOSFET. The microcontroller U5 controls which third MOSFET is turned on, thereby short-circuiting the resistor connected in parallel with that third MOSFET, determining which resistors are connected in series, and producing a precise and stable resistance value. Simultaneously, since the MOSFET itself has a certain internal resistance, which will affect the resistance value, a first load branch is designed. In this branch, multiple resistors connected in series are connected in parallel across the two ends of the second MOSFET. For example, MOSFET Q6 is connected across R11-R16, which can directly short-circuit R11-R16, thereby reducing the influence of the internal resistance of the multiple MOSFETs connected in parallel with R11-R16.

[0045] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A programmable resistive load circuit, characterized in that, include: The power supply module (1), optocoupler isolation module (2), serial-to-parallel conversion module (3), microcontroller U5 and regulating resistor module (4) are provided with power supply to the optocoupler isolation module (2), serial-to-parallel conversion module (3), microcontroller U5 and regulating resistor module (4). The output of the power supply module (1) supplies power to the optocoupler isolation module (2), serial-to-parallel conversion module (3), microcontroller U5 and regulating resistor module (4). The optocoupler isolation module (2) and serial-to-parallel conversion module (3) are electrically connected to the microcontroller U5. The serial-to-parallel conversion module (3) and microcontroller U5 are electrically connected to the regulating resistor module (4). The serial-to-parallel conversion module (3) includes two parallel registers, register U6 and register U7, and the regulating resistor module (4) includes a first regulating resistor circuit (41) and a second regulating resistor circuit (42). The microcontroller U5 is electrically connected to the first regulating resistor circuit (41), and the output terminals of the two registers are electrically connected to the second regulating resistor circuit (42). The first regulating resistor circuit (41) includes several first load branches composed of a first MOS transistor, a second MOS transistor and a first resistor. The second MOS transistor of each first load branch is connected in parallel with the first resistor and then in series with the first switch transistor. The second regulating resistor circuit (42) includes several second load branches composed of several third MOS transistors and several second resistors. Several second resistors are connected in series. Each second resistor is connected in parallel with a third MOS transistor. The two ends of each second MOS transistor are connected in parallel to the branch in which multiple second resistors are connected in series.

2. The programmable resistive load circuit according to claim 1, characterized in that, The power supply module (1) includes an isolated power supply module and a voltage regulator U3. The power supply module (1) is equipped with a 9V output voltage and a 5V output voltage.

3. The programmable resistive load circuit according to claim 1, characterized in that, The optocoupler isolation module (2) includes optocoupler U1 and optocoupler U2. Pin 6 of optocoupler U1 is electrically connected to pin 1 of microcontroller U5, and pin 3 of optocoupler U2 is electrically connected to pin 2 of microcontroller U5.

4. The programmable resistive load circuit according to claim 1, characterized in that, The serial-to-parallel conversion module (3) includes MOSFETs Q23, Q26, Q29, and Q31. Pin 3 of the microcontroller U5 is electrically connected to the gate of MOSFET Q23. The drain of MOSFET Q23 is connected to pin 1 of the two registers via a parallel resistor R23. Pin 19 of the microcontroller U5 is electrically connected to the gate of MOSFET Q26. The drain of MOSFET Q26 is connected to pin 2 of register U6 via a parallel resistor R27. Pin 18 of the microcontroller U5 is electrically connected to the gate of MOSFET Q29. The drain of MOSFET Q29 is connected to pin 3 of the two registers via a parallel resistor R29. Pin 17 of the microcontroller U5 is electrically connected to the gate of MOSFET Q31. The drain of MOSFET Q31 is connected to pin 15 of the two registers via a parallel resistor R31.

5. The programmable resistive load circuit according to claim 1, characterized in that, The first load branch has five branches, and pins 12-16 of the microcontroller U5 are electrically connected to the five first load branches respectively. The first MOSFETs include MOSFETs Q24, Q19, Q15, Q12 and Q8. The second MOSFETs include MOSFETs Q21, Q18, Q14, Q10 and Q6. The first resistors include resistors R24, R20, R17, R15 and R12.

6. The programmable resistive load circuit according to claim 5, characterized in that, Pin 12 of the microcontroller U5 is electrically connected to the gate of MOSFET Q24, and the drain of MOSFET Q24 is connected to the gate of MOSFET Q21 via a parallel resistor R24. Pin 13 of the microcontroller U5 is electrically connected to the gate of MOSFET Q19, and the drain of MOSFET Q19 is connected to the gate of MOSFET Q18 via a parallel resistor R20. Pin 14 of the microcontroller U5 is electrically connected to the gate of MOSFET Q15, and the drain of MOSFET Q25 is connected to the gate of MOSFET Q14 via a parallel resistor R17. Pin 15 of the microcontroller U5 is electrically connected to the gate of MOSFET Q12, and the drain of MOSFET Q12 is connected to the gate of MOSFET Q10 via a parallel resistor R15. Pin 16 of the microcontroller U5 is electrically connected to the gate of MOSFET Q8, and the drain of MOSFET Q8 is connected to the gate of MOSFET Q6 via a parallel resistor R12.

7. The programmable resistive load circuit according to claim 1, characterized in that, The second resistor includes resistors R1-R16, and the third MOSFET includes MOSFETs Q1-Q5, Q7, Q9, Q11, Q13, Q16-Q17, Q20, Q22, Q25, Q27-Q28, and Q30. The gate of each third MOSFET is connected to ground after a resistor is connected in parallel.

8. The programmable resistive load circuit according to claim 7, characterized in that, The second resistors R1-R16 are connected in series. Resistor R1 is connected in series with the third MOSFET Q30. Pin 11 of the microcontroller U5 is electrically connected to the gate of MOSFET Q30. Pin 4 of the register U6 is electrically connected to the gate of MOSFET Q28 and then connected in parallel with resistor R1. Pin 5 of the register U6 is electrically connected to the gate of MOSFET Q27 and then connected in parallel with resistor R2. Pin 6 of the register U6 is electrically connected to the gate of MOSFET Q25 and then connected in parallel with resistor R3. Pin 7 of the register U6 is electrically connected to the gate of MOSFET Q22 and then connected in parallel with resistor R4. Pin 14 of the register U6 is electrically connected to the gate of MOSFET Q20 and then connected in parallel with resistor R5. Pin 13 of the register U6 is electrically connected to the gate of MOSFET Q17 and then connected in parallel with resistor R6. Pin 12 of the register U6 is electrically connected to the gate of MOSFET Q16 and then connected in parallel with resistor R7. Pin 11 of the register U6 is electrically connected to the gate of MOSFET Q13 and then connected in parallel with resistor R8.

9. The programmable resistive load circuit according to claim 7, characterized in that, Pin 11 of the microcontroller U5 is electrically connected to the gate of MOSFET Q30; pin 4 of the register U7 is electrically connected to the gate of MOSFET Q11 with resistor R9 in parallel; pin 5 of the register U7 is electrically connected to the gate of MOSFET Q9 with resistor R10 in parallel; pin 6 of the register U7 is electrically connected to the gate of MOSFET Q7 with resistor R11 in parallel; pin 7 of the register U7 is electrically connected to the gate of MOSFET Q5 with resistor R12 in parallel; pin 14 of the register U7 is electrically connected to the gate of MOSFET Q3 with resistor R13 in parallel; pin 13 of the register U7 is electrically connected to the gate of MOSFET Q1 with resistor R14 in parallel; pin 12 of the register U7 is electrically connected to the gate of MOSFET Q4 with resistor R15 in parallel; and pin 11 of the register U7 is electrically connected to the gate of MOSFET Q2 with resistor R16 in parallel.

10. The programmable resistive load circuit according to claim 5 or 7, characterized in that, The drain of MOSFET Q21 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q21 is electrically connected to the source of MOSFET Q28; the drain of MOSFET Q18 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q18 is electrically connected to the source of MOSFET Q25; the drain of MOSFET Q14 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q14 is electrically connected to the source of MOSFET Q20; the drain of MOSFET Q10 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q10 is electrically connected to the source of MOSFET Q16; the drain of MOSFET Q6 is electrically connected to the drain of MOSFET Q2, and the source of MOSFET Q6 is electrically connected to the source of MOSFET Q7.

Images