High-precision direct-current low-resistance test circuit
By designing a high-precision DC low-resistance test circuit, and utilizing a combination of operational circuits, switching circuits, and isolation circuits, the problem of low accuracy in traditional testing methods is solved, achieving higher resistance testing accuracy and system stability.
Patent Information
- Application Number
- CN202422955296.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-11-18
- Estimated Expiration
- 2034-12-02
AI Technical Summary
Traditional low-precision testing methods result in low resistance testing accuracy, a large error range, difficulty in accurately determining the parameters of electronic components on circuit boards, and easy confusion.
A high-precision DC low-resistance test circuit is adopted, including a sampling unit, a data processing unit, a range switching unit, and a microcontroller. The control signal is processed by the arithmetic circuit, the range channel is controlled by the switching circuit, and the external interference is isolated by the isolation circuit, thus forming an error compensation mechanism.
It improves the accuracy of low resistance testing, reduces errors caused by signal fluctuations and nonlinearity, and ensures system stability and accuracy.
Smart Images
Figure CN223565786U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of low resistance testing technology, specifically a high-precision DC low resistance testing circuit. Background Technology
[0002] In our production process, circuit boards integrate many electronic components of different specifications, such as resistors and capacitors. During the initial debugging process, engineers constantly change the parameters of these components to achieve the best performance. The basic performance of the components changes depending on the soldering time, making it difficult to determine a specific parameter range. Traditional low-precision testing methods use a multimeter with a two-wire system, which is not only slow but also has poor accuracy, a wide error range, and is easily confused, resulting in low accuracy in low-resistance testing. Therefore, we need a high-precision DC low-resistance testing circuit to solve the above problems, enabling it to compensate for testing errors and effectively improve the accuracy of low-resistance testing. Utility Model Content
[0003] The purpose of this invention is to provide a high-precision DC low-resistance test circuit that can compensate for test errors and effectively improve the accuracy of low-resistance testing, thereby solving the problems mentioned in the background art.
[0004] To achieve the above objectives, this utility model provides the following technical solution: a high-precision DC low-resistance test circuit, comprising a sampling unit, a data processing unit, a range switching unit, and a microcontroller, wherein the sampling unit is electrically connected to the data processing unit, and the microcontroller is electrically connected to the sampling unit, the range switching unit, and the data processing unit respectively;
[0005] The range switching unit includes an arithmetic circuit for processing control signals, a switching circuit for controlling the on / off state of different range channels, and an isolation circuit for blocking external signals from interfering with the switching circuit. The arithmetic circuit is connected to a microcontroller, and the switching circuit is connected to both the arithmetic circuit and the isolation circuit.
[0006] Preferably, the sampling unit includes amplifier U5, amplifier U3, a four-way bidirectional analog switch U4, a four-way bidirectional modular switch U9, and a filter circuit connected to amplifier U5, amplifier U3, four-way bidirectional analog switch U4, and four-way bidirectional modular switch U9. A resistor array R18 is connected to the four-way bidirectional analog switch U9. The negative terminal of amplifier U5 is connected to pin 1 of the four-way bidirectional analog switch U5. The positive terminal of amplifier U5 is connected in series with resistors R12-2 and R12-1, and a receiver for receiving single-chip microcontrollers. The amplifier U5 has a resistor R12 for the VHT signal, and a resistor R13 is connected to the output terminal of the amplifier U5. One end of the resistor R13 is connected to pin 11 of the four-way bidirectional analog switch U4. Pins 9 and 10 of the four-way bidirectional analog switch U4 are both connected to the positive terminal of the amplifier U3 through resistor R11. The negative terminal of the amplifier U3 is connected to the output terminal through a resistor R77. One end of the resistor R77 is connected in parallel with a resistor R17 and a capacitor C10. The output terminal of the amplifier U3 is connected to the data processing unit through resistor R10.
[0007] Preferably, the filter circuit mainly consists of capacitors C15, C16, C45, C46, C78, and C79 connected in parallel. The connection terminals of capacitors C15, C16, C45, C46, C78, and C79 are grounded. The other terminals of capacitors C15 and C16 are connected to four-way bidirectional analog switches U9 and U4. The other terminals of capacitors C45 and C46 are connected to amplifier U5. The other terminals of capacitors C78 and C79 are connected to amplifier U3.
[0008] Preferably, the data processing unit includes an MCU chip U5. A capacitor C59 is connected to ground at pin 1 of the MCU chip U5, a capacitor C58 is connected to ground at pin 2 of the MCU chip U5, and a crystal oscillator Y2 is connected between the capacitors C58 and C59. A capacitor C12, a capacitor C13, and a capacitor C9 are connected in parallel at pin 24 of the MCU chip U5. An inductor L11 is connected to one of the terminals of capacitors C13 and C9. An amplifier chip U21 is connected to the terminal of inductor L11 connected to capacitor C9. A resistor R78 is connected to pin 4 of the amplifier chip U21. A resistor R79 is connected to one end of resistor R78. A capacitor C54 and a capacitor C62 are connected in parallel at one end of resistor R79. A capacitor C202 is connected to ground at the other terminal of capacitors C13 and C9.
[0009] Preferably, the arithmetic circuit includes arithmetic unit U6, arithmetic unit U7, and arithmetic unit U8. A resistor R87 is connected between the negative terminal and the output terminal of arithmetic unit U8. A resistor R27 for receiving microcontroller control signals is connected to the positive terminal of arithmetic unit U8. The output terminal of arithmetic unit U8 is connected to the negative terminal of arithmetic unit U7 through a resistor R88. A resistor R26 is connected between the negative terminal and the output terminal of arithmetic unit U7. A resistor R30 for receiving microcontroller control signals is connected to the positive terminal of arithmetic unit U7 through a resistor R28. A capacitor C38 is connected to ground to the positive terminal of arithmetic unit U6. A resistor R57 and a capacitor C37 are connected in parallel between the negative terminal and the output terminal of arithmetic unit U6. A resistor R29 is connected to the output terminal of arithmetic unit U6. One end of the resistor R29 is connected to a transistor Q2 for connection to a switching circuit.
[0010] Preferably, the switching circuit includes multiple MOSFETs connected in parallel for controlling the on / off state of different range channel circuits. The multiple MOSFETs are MOSFETs Q10, Q11, Q12, Q13, Q14, Q15, and Q16. A resistor RJ1 is connected to pin 2 of MOSFET Q10; a resistor R34 is connected to pin 2 of MOSFET Q11; a resistor R35 is connected to pin 2 of MOSFET Q12; a resistor R36 is connected to pin 2 of MOSFET Q13; a resistor R37 is connected to pin 2 of MOSFET Q14; and a resistor R37 is connected to pin 2 of MOSFET Q15. A resistor R38 is connected to the MOSFET Q16. A resistor R39 is connected to pin 2 of the MOSFET Q16. One end of the resistor RJ1 is connected to the MOSFET Q21. A MOSFET Q22 is connected to the connection point of the resistor R34 and the MOSFET Q11. A MOSFET Q23 is connected to the connection point of the resistor R35 and the MOSFET Q12. A MOSFET Q24 is connected to the connection point of the resistor R36 and the MOSFET Q13. MOSFETs Q21, Q22, Q23, and Q24 are connected in parallel. A diode D41, D42, D43, and D44 are connected in parallel to pin 1 of the MOSFET Q24.
[0011] Preferably, the isolation circuit includes multiple optocouplers U17 connected to each MOS transistor respectively. A resistor R43 is connected to pin 2 of each optocoupler U17, and a resistor R44 for connecting to the MOS transistor and a resistor R45 to ground are connected in parallel to pin 3 of each optocoupler U17.
[0012] Compared with the prior art, the beneficial effects of this utility model are:
[0013] 1. This utility model, through the cooperation of a sampling unit, a data processing unit, a range switching unit, and a microcontroller, constitutes a complete and efficient error compensation mechanism. It utilizes an arithmetic circuit to process control signals, performing appropriate calculations and adjustments on signals of different voltage ranges, enabling the system to respond more accurately to changes in the input signal. This helps reduce errors caused by signal fluctuations or nonlinearity. A switching circuit controls the on / off state of different range channels, ensuring rapid switching to the appropriate range when needed, avoiding measurement errors caused by range mismatch. An isolation circuit blocks external signals from interfering with the switching circuit, protecting the internal circuitry from external electromagnetic interference, thus maintaining system stability and accuracy and improving the precision of low-resistance testing. Attached Figure Description
[0014] Figure 1 This is a circuit block diagram of the present invention;
[0015] Figure 2 This is a circuit diagram of the sampling unit of this utility model;
[0016] Figure 3 This is a circuit diagram of the data processing unit of this utility model;
[0017] Figure 4 This is a circuit diagram of the operational circuit of this utility model;
[0018] Figure 5 This is a circuit diagram of the switching circuit of this utility model;
[0019] Figure 6 This is a circuit diagram of the isolation circuit of this utility model. Detailed Implementation
[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0021] Please see Figure 1-6 This utility model provides a technical solution: a high-precision DC low-resistance test circuit, including a sampling unit, a data processing unit, a range switching unit and a microcontroller, wherein the sampling unit is electrically connected to the data processing unit, and the microcontroller is electrically connected to the sampling unit, the range switching unit and the data processing unit respectively;
[0022] The sampling unit includes amplifier U5, amplifier U3, a four-channel bidirectional analog switch U4, a four-channel bidirectional module switch U9, and a filter circuit connected to amplifier U5, amplifier U3, the four-channel bidirectional analog switch U4, and the four-channel bidirectional module switch U9. A resistor array R18 is connected to the four-channel bidirectional analog switch U9. The negative terminal of amplifier U5 is connected to pin 1 of the four-channel bidirectional analog switch U5. Resistors R12-2, R12-1, and R12 (for receiving the microcontroller's VHT signal) are connected in series at the positive terminal of amplifier U5. A resistor R13 is connected to the output terminal of amplifier U5. One end of resistor R13 is connected to pin 11 of the four-channel bidirectional analog switch U4. Pins 9 and 10 of switch U4 are both connected to the positive terminal of amplifier U3 through resistor R11. The negative terminal of amplifier U3 is connected to the output terminal through resistor R77. One end of resistor R77 is connected in parallel with resistor R17 and capacitor C10. The output terminal of amplifier U3 is connected to the data processing unit through resistor R10 to receive analog signals from sensors or other signal sources. Amplifiers U5 and U3 are used to amplify weak input signals to a level suitable for further processing. Four-way bidirectional analog switches U4 and U9 are responsible for switching between different signal channels, which facilitates the selection of different signal channels according to control signals (such as control signals from the microcontroller) so as to process different signals.
[0023] The filtering circuit mainly consists of capacitors C15, C16, C45, C46, C78, and C79 connected in parallel. The connection terminals of capacitors C15, C16, C45, C46, C78, and C79 are grounded. The other terminals of capacitors C15 and C16 are connected to four-way bidirectional analog switches U9 and U4. The other terminals of capacitors C45 and C46 are connected to amplifier U5. The other terminals of capacitors C78 and C79 are connected to amplifier U3. The filtering circuit enhances or suppresses signals of a specific frequency.
[0024] The data processing unit includes an MCU chip U5. A capacitor C59 is connected to ground at pin 1 of the MCU chip U5, and a capacitor C58 is connected to ground at pin 2 of the MCU chip U5. A crystal oscillator Y2 is connected between capacitors C58 and C59. Capacitors C12, C13, and C9 are connected in parallel at pin 24 of the MCU chip U5. An inductor L11 is connected to one of the terminals of capacitors C13 and C9. An amplifier chip U21 is connected to the terminal of inductor L11 connected to capacitor C9. Pin 4 of the amplifier chip U21... A resistor R78 is connected to the top, and a resistor R79 is connected to one end of the resistor R78. A capacitor C54 and a capacitor C62 are connected in parallel to one end of the resistor R79. A capacitor C202 to ground is connected to the other end of the capacitors C13 and C9. The MCU chip U5 processes the acquired data. The capacitors C58 and C59 to ground are used for power supply decoupling and filtering to reduce the impact of power supply noise on the MCU chip U5. The amplifier chip U21, resistor R78, resistor R79, capacitor C54, and capacitor C62 work together to further amplify and filter the signal.
[0025] The range switching unit includes an arithmetic circuit for processing control signals, a switching circuit for controlling the on / off state of different range channels, and an isolation circuit for blocking external signals from interfering with the switching circuit. The arithmetic circuit is connected to a microcontroller, and the switching circuit is connected to both the arithmetic circuit and the isolation circuit.
[0026] The arithmetic circuit includes arithmetic units U6, U7, and U8. A resistor R87 is connected between the negative terminal and the output terminal of arithmetic unit U8. A resistor R27 for receiving microcontroller control signals is connected to the positive terminal of arithmetic unit U8. The output terminal of arithmetic unit U8 is connected to the negative terminal of arithmetic unit U7 via resistor R88. A resistor R26 is connected between the negative terminal and the output terminal of arithmetic unit U7. A resistor R30 for receiving microcontroller control signals is connected to the positive terminal of arithmetic unit U7. The output terminal of arithmetic unit U7 is connected to arithmetic unit U6 via resistor R28. The negative terminal of the arithmetic unit U6 is connected to the ground, and the positive terminal of the arithmetic unit U6 is connected to a capacitor C38. A resistor R57 and a capacitor C37 are connected in parallel between the negative terminal and the output terminal of the arithmetic unit U6. A resistor R29 is connected to the output terminal of the arithmetic unit U6, and one end of the resistor R29 is connected to a transistor Q2 for connection to the switching circuit. Through the coordinated use of arithmetic units U6, U7 and U8, it is convenient to perform appropriate calculations and adjustments on signals with different voltage ranges, so that the system can respond more accurately to changes in the input signal and reduce errors caused by signal fluctuations or nonlinearity.
[0027] The switching circuit includes multiple MOSFETs connected in parallel to control the on / off state of different range channel circuits. These MOSFETs are Q10, Q11, Q12, Q13, Q14, Q15, and Q16. Resistor RJ1 is connected to pin 2 of MOSFET Q10; resistor R34 is connected to pin 2 of MOSFET Q11; resistor R35 is connected to pin 2 of MOSFET Q12; resistor R36 is connected to pin 2 of MOSFET Q13; resistor R37 is connected to pin 2 of MOSFET Q14; resistor R38 is connected to pin 2 of MOSFET Q15; and resistor R39 is connected to pin 2 of MOSFET Q16. One end of resistor RJ1 is connected to MOSFET Q21. MOSFET Q22 is connected to the connection terminal of resistor R34 and MOSFET Q11. MOSFET Q23 is connected to the connection terminal of resistor R35 and MOSFET Q12. MOSFET Q24 is connected to the connection terminal of resistor R36 and MOSFET Q13. MOSFETs Q21, Q22, Q23, and Q24 are connected in parallel. Diodes D41, D42, D43, and D44 are connected in parallel to pin 1 of MOSFET Q24. The parallel connection of multiple MOSFETs facilitates the control of the on / off state of different range channels, ensuring a rapid switch to the appropriate range when needed and avoiding measurement errors caused by range mismatch.
[0028] The isolation circuit includes multiple optocouplers U17 connected to each MOSFET. A resistor R43 is connected to pin 2 of each optocoupler U17, and a resistor R44 for connecting to the MOSFET and a resistor R45 to ground are connected in parallel to pin 3 of each optocoupler U17. The optocouplers U17 block external signal interference to the switching circuit, protecting the internal circuit from external electromagnetic interference. Switching between different optocouplers achieves switching between different multiples. Each group of signals is isolated and does not affect each other, which helps maintain the stability and accuracy of the system and improves the accuracy of low resistance testing.
[0029] A complete and efficient error compensation mechanism is formed by the cooperation of the sampling unit, data processing unit, range switching unit, and microcontroller. The arithmetic circuit processes the control signal and performs appropriate calculations and adjustments on signals of different voltage ranges, enabling the system to respond more accurately to changes in the input signal and reduce errors caused by signal fluctuations or nonlinearity. The switching circuit controls the on / off state of different range channels, ensuring that the appropriate range can be quickly switched when needed, avoiding measurement errors caused by range mismatch. The isolation circuit is used to block external signals from interfering with the switching circuit and protect the internal circuit from external electromagnetic interference, which helps to maintain the stability and accuracy of the system and improves the accuracy of low resistance testing.
[0030] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A high-precision DC low-resistance test circuit, characterized in that: It includes a sampling unit, a data processing unit, a range switching unit, and a microcontroller. The sampling unit is electrically connected to the data processing unit, and the microcontroller is electrically connected to the sampling unit, the range switching unit, and the data processing unit respectively. The range switching unit includes an arithmetic circuit for processing control signals, a switching circuit for controlling the on / off state of different range channels, and an isolation circuit for blocking external signals from interfering with the switching circuit. The arithmetic circuit is connected to a microcontroller, and the switching circuit is connected to both the arithmetic circuit and the isolation circuit.
2. The high-precision DC low-resistance test circuit according to claim 1, characterized in that: The sampling unit includes amplifier U5, amplifier U3, a four-way bidirectional analog switch U4, a four-way bidirectional module switch U9, and a filter circuit connected to amplifier U5, amplifier U3, four-way bidirectional analog switch U4, and four-way bidirectional module switch U9. A resistor array R18 is connected to the four-way bidirectional analog switch U9. The negative terminal of amplifier U5 is connected to pin 1 of the four-way bidirectional analog switch U5. Resistors R12-2 and R12-1 are connected in series at the positive terminal of amplifier U5, along with a receiver for receiving signals from the microcontroller V. The HT signal is connected to resistor R12. The output terminal of amplifier U5 is connected to resistor R13. One end of resistor R13 is connected to pin 11 of four-way bidirectional analog switch U4. Pins 9 and 10 of four-way bidirectional analog switch U4 are both connected to the positive terminal of amplifier U3 through resistor R11. The negative terminal of amplifier U3 is connected to the output terminal through resistor R77. One end of resistor R77 is connected in parallel with resistor R17 and capacitor C10. The output terminal of amplifier U3 is connected to the data processing unit through resistor R10.
3. The high-precision DC low-resistance test circuit according to claim 2, characterized in that: The filtering circuit mainly consists of capacitors C15, C16, C45, C46, C78, and C79 connected in parallel. The connection terminals of capacitors C15, C16, C45, C46, C78, and C79 are grounded. The other terminals of capacitors C15 and C16 are connected to four-way bidirectional analog switches U9 and U4. The other terminals of capacitors C45 and C46 are connected to amplifier U5. The other terminals of capacitors C78 and C79 are connected to amplifier U3.
4. The high-precision DC low-resistance test circuit according to claim 3, characterized in that: The data processing unit includes an MCU chip U5. A capacitor C59 is connected to ground at pin 1 of the MCU chip U5, and a capacitor C58 is connected to ground at pin 2 of the MCU chip U5. A crystal oscillator Y2 is connected between the capacitors C58 and C59. A capacitor C12, a capacitor C13, and a capacitor C9 are connected in parallel at pin 24 of the MCU chip U5. An inductor L11 is connected to one of the terminals of capacitors C13 and C9. An amplifier chip U21 is connected to the terminal of inductor L11 connected to capacitor C9. A resistor R78 is connected to pin 4 of the amplifier chip U21. A resistor R79 is connected to one end of resistor R78. A capacitor C54 and a capacitor C62 are connected in parallel at one end of resistor R79. A capacitor C202 is connected to ground at the other terminal of capacitors C13 and C9.
5. The high-precision DC low-resistance test circuit according to claim 1, characterized in that: The arithmetic circuit includes arithmetic units U6, U7, and U8. A resistor R87 is connected between the negative terminal and the output terminal of arithmetic unit U8. A resistor R27 for receiving microcontroller control signals is connected to the positive terminal of arithmetic unit U8. The output terminal of arithmetic unit U8 is connected to the negative terminal of arithmetic unit U7 via resistor R88. A resistor R26 is connected between the negative terminal and the output terminal of arithmetic unit U7. A resistor R30 for receiving microcontroller control signals is connected to the positive terminal of arithmetic unit U7. The output terminal of arithmetic unit U7 is connected to the negative terminal of arithmetic unit U6 via resistor R28. A capacitor C38 is connected to ground to the positive terminal of arithmetic unit U6. A resistor R57 and a capacitor C37 are connected in parallel between the negative terminal and the output terminal of arithmetic unit U6. A resistor R29 is connected to the output terminal of arithmetic unit U6, and one end of resistor R29 is connected to a transistor Q2 for connection to a switching circuit.
6. The high-precision DC low-resistance test circuit according to claim 1, characterized in that: The switching circuit includes multiple MOSFETs connected in parallel to control the on / off state of different range channel circuits. These MOSFETs are Q10, Q11, Q12, Q13, Q14, Q15, and Q16. Resistor RJ1 is connected to pin 2 of MOSFET Q10; resistor R34 is connected to pin 2 of MOSFET Q11; resistor R35 is connected to pin 2 of MOSFET Q12; resistor R36 is connected to pin 2 of MOSFET Q13; resistor R37 is connected to pin 2 of MOSFET Q14; and resistor RJ1 is connected to pin 2 of MOSFET Q15. Resistor R38; resistor R39 is connected to pin 2 of MOSFET Q16; one end of resistor RJ1 is connected to MOSFET Q21; MOSFET Q22 is connected to the connection terminal of resistor R34 and MOSFET Q11; MOSFET Q23 is connected to the connection terminal of resistor R35 and MOSFET Q12; MOSFET Q24 is connected to the connection terminal of resistor R36 and MOSFET Q13; MOSFETs Q21, Q22, Q23, and Q24 are connected in parallel; diodes D41, D42, D43, and D44 are connected in parallel to pin 1 of MOSFET Q24.
7. The high-precision DC low-resistance test circuit according to claim 1, characterized in that: The isolation circuit includes multiple optocouplers U17 connected to each MOS transistor respectively. A resistor R43 is connected to pin 2 of each optocoupler U17, and a resistor R44 for connecting to the MOS transistor and a resistor R45 to ground are connected in parallel to pin 3 of each optocoupler U17.