Board test load circuit and device

Abstract

The present invention discloses a board card test load circuit and device, which includes a regulation and sampling module, a synchronous switch module, a feedback comparison module, a first and a second instrumentation amplifier module, and a microprocessor. A current regulation unit is configured on the high-current branch to achieve the regulation of the pulling current. A first four-pin sampling resistor and a second four-pin sampling resistor are configured on the high-current branch, which can improve the measurement accuracy. During the measurement, the microprocessor controls the synchronous switching of the single-channel switch unit and the multi-channel gating switch unit through the synchronous control unit of the synchronous switch module to adapt to the test application scenarios of high current and low current, and respectively performs signal acquisition through the first instrumentation amplifier module and the second instrumentation amplifier module to achieve feedback regulation. The microprocessor also adjusts the control signals of the current regulation unit and the synchronous control unit according to the error calibration data stored in the storage module and the detection data from the DMM module to achieve the precise control of the pulling current, which is beneficial to improving the test accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of test equipment, and particularly relates to a board test load circuit and device. Background Art

[0002] A mobile power supply (such as a power bank) is a power product used to supply power to electronic mobile devices. With the continuous development of technology, the charging efficiency requirements of electronic mobile devices are getting higher and higher, resulting in an increasing load current of the mobile power supply. In order to ensure the safety performance of product use, it is necessary to test the main board of the mobile power supply during the production process. However, the test equipment of related technologies is difficult to meet the test requirements of the gradually increasing load current of the mobile power supply. It is necessary to customize test equipment for high-current mobile power supplies, which has a high test cost. Moreover, the customized equipment has a low test accuracy for mobile power supplies with a small load current and low versatility. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides a board test load circuit and device, which can be compatible with the test of products with large currents and small currents and has high test accuracy.

[0004] On the one hand, an embodiment of the present invention provides a board test load circuit, including:

[0005] A regulation and sampling module, which is arranged on the large-current branch. The regulation and sampling module includes a current regulation unit, a first four-pin sampling resistor, and a second four-pin sampling resistor. The high-voltage end of the current regulation unit is used as the load output end. The low-voltage end of the current regulation unit is connected to the first main pin of the first four-pin sampling resistor. The second main pin of the first four-pin sampling resistor is connected to the first main pin of the second four-pin sampling resistor. The second main pin of the second four-pin sampling resistor is connected to the reference voltage end;

[0006] A synchronous switch module, including a single-channel switch unit, a multi-channel selection switch unit, and a synchronous control unit. The two ends of the single-channel switch unit are respectively connected to the large-current branch and are connected in parallel to the first four-pin sampling resistor. The first moving connection end of the multi-channel selection switch unit is connected to the first detection pin of the second four-pin sampling resistor. The second moving connection end of the multi-channel selection switch unit is connected to the first detection pin of the first four-pin sampling resistor. The first input end of the synchronous control unit is connected to the first detection pin of the first four-pin sampling resistor. The output end of the synchronous control unit is connected to the control end of the single-channel switch unit and the control end of the multi-channel selection switch unit;

[0007] A feedback comparison module, the output end of which is connected to the control end of the current regulation unit;

[0008] The first instrumentation amplifier module, the first input terminal of which is connected to the static connection terminal of the multiplexing switch unit, the second input terminal of the first instrumentation amplifier module is connected to the second detection pin of the second four-pin sampling resistor, and the output terminal of the first instrumentation amplifier module is connected to the second input terminal of the feedback comparison module;

[0009] The second instrumentation amplifier module, the first input terminal of which is connected to the static connection terminal of the multiplexing switch unit, the second input terminal of the second instrumentation amplifier module is connected to the second detection pin of the second four-pin sampling resistor, and the output terminal of the second instrumentation amplifier module is used to connect to the DMM module;

[0010] The microprocessor is connected to the DAC module and the storage module. The microprocessor is connected to the first input terminal of the feedback comparison module through the DAC module. The microprocessor is also connected to the DMM module and the second input terminal of the synchronization control unit. The microprocessor is used to adjust the control signals of the current regulation unit and the synchronization control unit according to the error calibration data stored in the storage module and the detection data from the DMM module.

[0011] According to some embodiments of the present invention, the synchronization control unit includes a first comparator, a first switching transistor, a logic gate component, and a second switching transistor. The non-inverting input terminal of the first comparator is connected to a first voltage dividing branch. The inverting input terminal of the first comparator is connected to the first detection pin of the first four-pin sampling resistor. The control terminal of the first switching transistor is connected to the output terminal of the first comparator. The high-voltage terminal of the first switching transistor is connected to the first input terminal of the logic gate component. The second input terminal of the logic gate component is connected to the microprocessor. The output terminal of the logic gate component is connected to the control terminal of the second switching transistor. The high-voltage terminal of the second switching transistor is connected to the control terminal of the single-channel switch unit and the control terminal of the multiplexing switch unit.

[0012] According to some embodiments of the present invention, the logic gate component is a NOR gate component.

[0013] According to some embodiments of the present invention, the single-channel switch unit and the multiplexing switch unit are integrated in the same relay.

[0014] According to some embodiments of the present invention, the first instrumentation amplifier module includes a first instrumentation amplifier. The non-inverting input terminal of the first instrumentation amplifier is connected to the static connection terminal of the multiplexing switch unit. The inverting input terminal of the first instrumentation amplifier is connected to the second detection terminal of the second four-pin sampling resistor.

[0015] According to some embodiments of the present invention, the gain coefficient of the first instrumentation amplifier module is 1.

[0016] According to some embodiments of the present invention, the second instrumentation amplifier module includes a second instrumentation amplifier. The non-inverting input terminal of the second instrumentation amplifier is connected to the static connection terminal of the multiplexing switch unit, and the inverting input terminal of the second instrumentation amplifier is connected to the second detection terminal of the second four-pin sampling resistor.

[0017] According to some embodiments of the present invention, a gain selection unit is connected to the gain configuration terminal of the second instrumentation amplifier, and the input terminal of the gain selection unit is connected to the microprocessor.

[0018] According to some embodiments of the present invention, a voltage stabilization unit is connected to the output terminal of the second instrumentation amplifier module.

[0019] On the other hand, an embodiment of the present invention provides a board test device, including the above-mentioned board test load circuit.

[0020] The embodiments of the present invention at least have the following beneficial effects:

[0021] A current regulation unit is configured on the high-current branch to achieve the regulation of the pulling current. A first four-pin sampling resistor and a second four-pin sampling resistor are configured on the high-current branch, which can improve the measurement accuracy. During the measurement process, the microprocessor controls the synchronous switching of the single-channel switch unit and the multiplexing switch unit through the synchronous control unit of the synchronous switch module to adapt to the test application scenarios of high current and low current, and respectively performs signal acquisition through the first instrumentation amplifier module and the second instrumentation amplifier module to achieve feedback regulation. The microprocessor also adjusts the control signals of the current regulation unit and the synchronous control unit according to the error calibration data stored in the storage module and the detection data from the DMM module, realizing the precise control of the pulling current, which is beneficial to improving the test accuracy.

[0022] The additional aspects and advantages of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0024] Figure 1 is a schematic block diagram of the board test load circuit according to an embodiment of the present invention;

[0025] Figure 2 is Figure 1 a schematic circuit diagram of the regulation and sampling module of the board test load circuit shown;

[0026] Figure 3 is Figure 1Circuit schematic diagram of the feedback comparison module of the board test load circuit shown;

[0027] Figure 4 is Figure 1 Circuit schematic diagram of the synchronization control unit of the board test load circuit shown;

[0028] Figure 5 is Figure 1 Circuit schematic diagram of the first instrumentation amplifier module of the board test load circuit shown;

[0029] Figure 6 is Figure 1 Circuit schematic diagram of the second instrumentation amplifier module of the board test load circuit shown;

[0030] Figure 7 is Figure 1 Circuit schematic diagram of the gain selection unit of the board test load circuit shown.

[0031] Reference numerals:

[0032] Regulation and sampling module 100, high-current branch 101, current regulation unit 110, first four-pin sampling resistor 120, second four-pin sampling resistor 130, synchronization switch module 200, single-channel switch unit 210, multi-channel gating switch unit 220, synchronization control unit 230, feedback comparison module 300, first instrumentation amplifier module 400, second instrumentation amplifier module 500, gain selection unit 510, DMM module 600, microprocessor 700, DAC module 710, storage module 720. Detailed implementation manners

[0033] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0034] In the description of the present invention, the meaning of "several" is one or more, the meaning of "multiple" is two or more, greater than, less than, exceeding, etc. are understood as not including the present number, and "above", "below", "within", etc. are understood as including the present number. If there is a description of "first", "second", etc., it is only for the purpose of distinguishing technical features and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0035] In the description of the present invention, unless otherwise clearly defined, terms such as "set", "installed", "connected" should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0036] The test items of the mobile power supply are related to the load current. Stable and accurate control of the load current is beneficial to improving the test accuracy. In the related art, for the customized test equipment in the large-current test scenario, although it can also be applied to the small-current test scenario, the control accuracy of the load current is low, resulting in low test accuracy and unable to meet the high-precision test requirements, so that the versatility of the customized test equipment is not high.

[0037] This embodiment discloses a board test device, including a board test load circuit. Please refer to Figure 1 , the board test load circuit includes a regulation and sampling module 100, a synchronous switch module 200, a feedback comparison module 300, a first instrumentation amplifier module 400, a second instrumentation amplifier module 500, and a microprocessor 700.

[0038] The regulation and sampling module 100 is arranged on the large-current branch 101. The regulation and sampling module 100 includes a current regulation unit 110, a first four-pin sampling resistor 120, and a second four-pin sampling resistor 130. The high-voltage end of the current regulation unit 110 is used as the load output end. The low-voltage end of the current regulation unit 110 is connected to the first main pin of the first four-pin sampling resistor 120. The second main pin of the first four-pin sampling resistor 120 is connected to the first main pin of the second four-pin sampling resistor 130. The second main pin of the second four-pin sampling resistor 130 is connected to the reference voltage terminal.

[0039] The synchronous switch module 200 includes a single-channel switch unit 210, a multi-channel gating switch unit 220, and a synchronous control unit 230. The two ends of the single-channel switch unit 210 are respectively connected to the large-current branch 101 and are connected in parallel to the first four-pin sampling resistor 120. The first moving connection end of the multi-channel gating switch unit 220 is connected to the first detection pin of the second four-pin sampling resistor 130. The second moving connection end of the multi-channel gating switch unit 220 is connected to the first detection pin of the first four-pin sampling resistor 120. The first input end of the synchronous control unit 230 is connected to the first detection pin of the first four-pin sampling resistor 120. The output end of the synchronous control unit 230 is connected to the control end of the single-channel switch unit 210 and the control end of the multi-channel gating switch unit 220.

[0040] The output terminal of the feedback comparison module 300 is connected to the control terminal of the current regulation unit 110. The first input terminal of the first instrumentation amplifier module 400 is connected to the static connection terminal of the multiplexer switch unit 220. The second input terminal of the first instrumentation amplifier module 400 is connected to the second detection pin of the second four-pin sampling resistor 130. The output terminal of the first instrumentation amplifier module 400 is connected to the second input terminal of the feedback comparison module 300. The first input terminal of the second instrumentation amplifier module 500 is connected to the static connection terminal of the multiplexer switch unit 220. The second input terminal of the second instrumentation amplifier module 500 is connected to the second detection pin of the second four-pin sampling resistor 130. The output terminal of the second instrumentation amplifier module 500 is used to connect to the DMM module 600, where DMM means digital multimeter.

[0041] The microprocessor 700 is connected to a DAC module 710 and a storage module 720. The microprocessor 700 is connected to the first input terminal of the feedback comparison module 300 through the DAC module 710. The microprocessor 700 is also connected to the DMM module 600 and the second input terminal of the synchronization control unit 230. The microprocessor 700 is used to adjust the control signals of the current regulation unit 110 and the synchronization control unit 230 according to the error calibration data stored in the storage module 720 and the detection data from the DMM module 600.

[0042] In order to meet the high-precision test performance, in this embodiment, the control idea based on feedback regulation is used to precisely regulate the load current output to a load (such as a mobile power supply).

[0043] Among them, please refer to Figure 2, the current regulation unit 110 is used to regulate the pull current flowing through the high-current branch 101. For example, the current regulation unit 110 can use a field-effect transistor or an integrated chip with current regulation function. The high-current branch 101 can allow a relatively large pull current, thus being compatible with test scenarios of both high current and low current. Among them, the high-current branch 101 can be realized by laying a wider line in the circuit layout (layout). For example, if the rated current of the design is 4A, the line width for a 5A overcurrent is used for wiring during wiring. However, as the line width increases, the line resistance of the line will also affect the measurement of current or voltage. If a conventional surface-mount resistor with only two terminals is used as the sampling resistor, it is difficult to eliminate the influence of the power supply voltage and the wire resistance on the measurement result. During the design process, attempts were made to reduce the influence of the aforementioned factors on the measurement result through circuit wiring techniques, but the measurement result still could not meet the expected accuracy requirements. Through continuous experiments and empirical analysis, using four-terminal sampling resistors (such as the first four-terminal sampling resistor 120 and the second four-terminal sampling resistor 130) as the sampling resistors for the high-current branch 101 helps to improve the measurement accuracy. It should be noted that a four-terminal sampling resistor, also called a four-wire resistor, is a special type of resistor that plays a role in accurately measuring the resistance value in a circuit. The four-terminal resistor uses a four-wire connection method, that is, two of the terminals are used for current input (such as the first main pin and the second main pin), and the other two terminals are used for voltage measurement (such as the first detection pin and the second detection pin). This connection method can eliminate the influence of the power supply voltage and the wire resistance (i.e., line resistance) in the circuit on the measurement result, ensuring the accuracy of the measurement value and being applicable to application scenarios with high-precision measurement.

[0044] In addition, the resistance value of the sampling resistor will also affect the accuracy of the measurement result. By connecting the single-channel switch unit 210 in parallel at both ends of the first four-terminal sampling resistor 120, the selective access or disconnection of the first four-terminal sampling resistor 120 can be realized, thereby adjusting the total resistance value of the sampling resistor on the high-current branch 101. In this way, the function of using a large resistor to measure a small current and using a small resistor to measure a large current can be realized, which is beneficial to improving the measurement accuracy in the small-current scenario and further being compatible with test scenarios of both high current and low current.

[0045] Please refer to Figure 2 , the sampling signal collected through the sampling resistor on the high-current branch 101 is used for feedback regulation. Among them, the sampling signal is divided into two paths. The first path of the sampling signal is fed back to the feedback comparison module 300. The circuit schematic diagram of the feedback comparison module 300 is as Figure 3As shown, the feedback comparison module 300 has a first input terminal and a second input terminal. The first input terminal of the feedback comparison module 300 is used to receive the first control signal (such as labeled I_E_Load_SET) output by the microprocessor 700. The first control signal output by the microprocessor 700 is output to the first input terminal of the feedback comparison module 300 after digital-to-analog conversion by the DAC module 710. The second input terminal of the feedback comparison module 300 is used to receive the first path of sampling signal (such as labeled E_LOAD_FB). In this way, the first control signal and the first path of sampling signal are compared and processed by the feedback comparison module 300, and the current regulation unit 110 is controlled through the comparison output result to achieve internal feedback regulation of the circuit. The second path of sampling signal is output to the DMM module 600 through the second instrumentation amplifier module 500. The DMM module 600 can be an internal module or an external module. Considering the operation habit of users who hope to observe the measurement results from different dimensions (or use different devices) in the actual application scenario, in this embodiment, the external DMM module 600 is taken as an example. After data processing, the DMM module 600 outputs the measurement result to the microprocessor 700. The microprocessor 700 adjusts the first control signal used to control the current regulation unit 110 according to the error calibration data stored in the storage module 720 and the detection data from the DMM module 600 to achieve external feedback regulation of the circuit. Through the cooperation of internal feedback regulation and external feedback regulation, both the rapid dynamic regulation of the pull load current inside the circuit and the real-time monitoring and feedback regulation of the pull load current outside the circuit can be achieved, thereby improving the accuracy of pull load current regulation and further improving the accuracy of testing.

[0046] Among them, the error calibration data in the storage module 720 (such as EEPROM) is pre-stored. For example, in the circuit debugging stage, the above circuit is built and the feedback current data (detection data) corresponding to multiple current data (output data) output by the microprocessor 700 is measured through the DMM module 600, and the error calibration data is determined according to the output data and the detection data. Among them, the error calibration data includes a calibration coefficient and a deviation value. There is a linear relationship between the calibrated signal (i.e., the first control signal) and the original signal, such as calibrated signal = calibration coefficient × original signal + deviation value. By calibrating the original signal to be output by the microprocessor 700 with the error calibration data, the accuracy of the output signal can be improved, and the output signal of the microprocessor 700 can be adjusted in real time according to the feedback signal measured by the DMM module 600, further improving the regulation accuracy of the pull load current.

[0047] It is worth mentioning that the first instrumentation amplifier module 400 and the second instrumentation amplifier module 500 are gain amplification modules based on instrumentation amplifiers. Instrumentation amplifiers have high precision and small errors, can amplify and measure tiny signals, can maintain the stability of the amplifier circuit, reduce the influence of temperature drift and noise, and have low background noise, which can reduce the noise interference in the signal. In addition, they also have the function of filtering the input signal to eliminate noise and clutter. The first instrumentation amplifier module 400 and the second instrumentation amplifier module 500 based on instrumentation amplifiers are applicable to circuits for high-precision measurement.

[0048] In addition, in order to achieve synchronous control, the output end of the synchronous control unit 230 is connected to the control end of the single-channel switch unit 210 and the control end of the multi-channel gating switch unit 220, and the first input end of the synchronous control unit 230 is connected to the first detection pin of the first four-pin sampling resistor 120, and the second input end of the synchronous control unit 230 is connected to the microprocessor 700. In this way, dynamic control can be carried out according to the feedback signal of the high-current branch 101 and the output signal of the microprocessor 700, so as to flexibly and accurately change the sampling resistor on the high-current branch 101, which is beneficial to improving the accuracy of detection.

[0049] A current regulation unit 110 is configured on the high-current branch 101 to achieve the regulation of the pull load current. Configuring the first four-pin sampling resistor 120 and the second four-pin sampling resistor 130 on the high-current branch 101 can improve the measurement accuracy. During the measurement process, the microprocessor 700 controls the synchronous switching of the single-channel switch unit 210 and the multi-channel gating switch unit 220 through the synchronous control unit 230 of the synchronous switch module 200 to adapt to the test application scenarios of high current and low current, and respectively collects signals through the first instrumentation amplifier module 400 and the second instrumentation amplifier module 500 to achieve feedback regulation. The microprocessor 700 also adjusts the control signals of the current regulation unit 110 and the synchronous control unit 230 according to the error calibration data stored in the storage module 720 and the detection data from the DMM module 600 to achieve precise control of the pull load current, which is beneficial to improving the test accuracy. It should be noted that the first four-pin sampling resistor 120, the second four-pin sampling resistor 130, the synchronous control unit 230, the single-channel switch unit 210, the multi-channel gating switch unit 220, the first instrumentation amplifier module 400, the second instrumentation amplifier module 500, the DMM module 600, the microprocessor 700 and the storage module 720 form an organic and complete feedback regulation network and jointly achieve high-precision regulation of the pull load current, thereby improving the test accuracy.

[0050] Please refer to Figure 4, the synchronization control unit 230 includes a first comparator (shown as label U1800B), a first switching transistor (shown as label Q1802), a logic gate component (shown as label U1805), and a second switching transistor (shown as label Q1801). The non-inverting input terminal of the first comparator is connected to a first voltage dividing branch, for example, a voltage dividing branch composed of resistor R1835 and resistor R1836. The inverting input terminal of the first comparator is connected to the first detection pin of the first four-pin sampling resistor 120. The control terminal of the first switching transistor is connected to the output terminal of the first comparator. The high-voltage terminal of the first switching transistor is connected to the first input terminal of the logic gate component (shown as label E_Load_RANGE_1). The second input terminal of the logic gate component (shown as label E_Load_RANGE_2) is connected to the microprocessor 700. The output terminal of the logic gate component is connected to the control terminal of the second switching transistor. The high-voltage terminal of the second switching transistor is connected to the control terminals of the single-channel switching unit 210 and the multi-channel selection switch unit 220. When the load current is a small current, the sampling signal of the first four-pin sampling resistor 120 can be transmitted to the first comparator. The first comparator compares the sampling signal from the first four-pin sampling resistor 120 and the voltage dividing signal of the first voltage dividing branch, so as to monitor the load current of the large current branch 101 in real time. The comparison signal of the first comparator is output to the first switching transistor, thereby controlling the conduction and cutoff of the first switching transistor, and further providing a first input signal to the logic gate component. The logic gate component performs logic operation processing on the first input signal and the control signal of the microprocessor 700, and controls the conduction and cutoff of the second switching transistor according to the processing result, and further synchronously controls the single-channel switching unit 210 and the multi-channel selection switch unit 220 to achieve the self-locking of the single-channel switching unit 210 and the multi-channel selection switch unit 220 in the small current state. Among them, the logic gate component is a NOR gate component. In some other application examples, the logic gate component can also adopt an OR gate component, an exclusive OR gate component, or a coincidence gate component, etc., but the circuit structure needs to be adjusted adaptively.

[0051] Please refer to Figure 2, the single - path switch unit 210 and the multi - path gating switch unit 220 are integrated into the same relay (as shown by the label K1800). Among them, the 6th and 7th pins of the relay are used as the two connection terminals of the single - path switch unit 210, the 3rd pin of the relay is used as the static connection terminal of the multi - path gating switch unit 220, and the 2nd and 4th pins of the relay are used as the first moving connection terminal and the second moving connection terminal of the multi - path gating switch unit 220 respectively. In the high - current state, the 6th and 7th pins of the relay are conducting, and the 3rd and 2nd pins of the relay are connected; when the current is less than the preset threshold, the microprocessor 700 sends a control signal to the logic gate component, the logic gate component sends a conduction signal to the second switching tube, the second switching tube conducts to make the relay pull in, the 6th and 7th pins of the relay are disconnected, the 3rd pin of the relay is connected to the 4th pin, and the sampling signal of the first four - pin sampling resistor 120 can be transmitted to the first comparator, and the self - locking of the relay is realized through the first comparator, the first switching tube and the logic gate component.

[0052] Please refer to Figure 5 , the first instrumentation amplifier module 400 includes a first instrumentation amplifier (as shown by the label U1803). The non - inverting input terminal of the first instrumentation amplifier is connected to the static connection terminal of the multi - path gating switch unit 220, and the connection node is as shown by the label E_LOAD_SNS_P. The inverting input terminal of the first instrumentation amplifier is connected to the second detection terminal of the second four - pin sampling resistor 130, and the connection node is as shown by the label E_LOAD_SNS_N. The first instrumentation amplifier module 400 can feedback the current signal on the high - current path to the feedback comparison module 300. Compared with the conventional feedback resistor, the sampling accuracy of the first instrumentation amplifier is higher, and the common - mode interference can be eliminated. It is worth mentioning that the high - current branch 101 has a higher temperature during operation, and heat dissipation treatment and thermal management control need to be carried out on the current regulation unit 110. In addition, a higher - temperature working environment is likely to cause thermal noise and the performance parameters of components to drift. The gain coefficient of the first instrumentation amplifier module 400 is 1, which can increase the input resistance, reduce the output resistance, play a buffering role, and can also eliminate the common - mode interference caused by factors such as temperature and electromagnetic interference, suppress zero - point drift, and improve the reliability of the circuit operation.

[0053] Please refer to Figure 6 , the second instrumentation amplifier module 500 includes a second instrumentation amplifier. The non - inverting input terminal of the second instrumentation amplifier is connected to the static connection terminal of the multi - path gating switch unit 220, and the connection node is as shown by the label E_LOAD_SNS_P. The inverting input terminal of the second instrumentation amplifier is connected to the second detection terminal of the second four - pin sampling resistor 130, and the connection node is as shown by the label E_LOAD_SNS_N. The second instrumentation amplifier has characteristics such as high common - mode rejection ratio, high input impedance, low noise, low linear error, low offset drift, and flexible gain setting. Moreover, please refer toFigure 6 and Figure 7 , the gain configuration terminals of the second instrumentation amplifier (as shown by the markings GAIN_G1 and GAIN_G2 in Figure 6 ) are connected to a gain selection unit 510. The input end of the gain selection unit 510 is connected to the microprocessor 700. Different gains can be switched through the gain selection unit 510 according to the actual application requirements, so as to amplify the small current signal and improve the accuracy of small current signal detection.

[0054] Please refer to Figure 6 . In order to further improve the stability of the circuit operation, the output end of the second instrumentation amplifier module 500 is connected to a voltage stabilizing unit, such as a voltage stabilizing diode marked D1800, which can play a role in stabilizing the output voltage signal, improve the stability of the input signal of the DMM module 600, and thus improve the accuracy and precision of detection. Among them, the marking E_LOAD_CURRENT is the connection terminal connected to the DMM module 600.

[0055] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A board card test load circuit, characterized in that, Including: A regulation and sampling module (100) is disposed on the high-current branch (101). The regulation and sampling module (100) includes a current regulation unit (110), a first four-pin sampling resistor (120), and a second four-pin sampling resistor (130). The high-voltage end of the current regulation unit (110) serves as the load output end. The low-voltage end of the current regulation unit (110) is connected to the first main pin of the first four-pin sampling resistor (120). The second main pin of the first four-pin sampling resistor (120) is connected to the first main pin of the second four-pin sampling resistor (130). The second main pin of the second four-pin sampling resistor (130) is connected to the reference voltage terminal. A synchronous switch module (200) includes a single-channel switch unit (210), a multi-channel gating switch unit (220), and a synchronous control unit (230). Both ends of the single-channel switch unit (210) are respectively connected to the high-current branch (101) and are connected in parallel to the main pins of the first four-pin sampling resistor (120). The first moving connection end of the multi-channel gating switch unit (220) is connected to the first detection pin of the second four-pin sampling resistor (130). The second moving connection end of the multi-channel gating switch unit (220) is connected to the first detection pin of the first four-pin sampling resistor (120). The first input end of the synchronous control unit (230) is connected to the first detection pin of the first four-pin sampling resistor (120). The output end of the synchronous control unit (230) is connected to the control end of the single-channel switch unit (210) and the control end of the multi-channel gating switch unit (220). A feedback comparison module (300), whose output end is connected to the control end of the current regulation unit (110). A first instrumentation amplifier module (400), whose first input end is connected to the static connection end of the multi-channel gating switch unit (220). The second input end of the first instrumentation amplifier module (400) is connected to the second detection pin of the second four-pin sampling resistor (130). The output end of the first instrumentation amplifier module (400) is connected to the second input end of the feedback comparison module (300). A second instrumentation amplifier module (500), whose first input end is connected to the static connection end of the multi-channel gating switch unit (220). The second input end of the second instrumentation amplifier module (500) is connected to the second detection pin of the second four-pin sampling resistor (130). The output end of the second instrumentation amplifier module (500) is used to connect to the DMM module (600). A microprocessor (700) is connected to a DAC module (710) and a storage module (720), wherein the microprocessor (700) is connected to a first input terminal of the feedback comparison module (300) via the DAC module (710), and the microprocessor (700) is further connected to a second input terminal of the DMM module (600) and the synchronization control unit (230), and the microprocessor (700) is used to adjust the control signals of the current control unit (110) and the synchronization control unit (230) according to the error calibration data stored in the storage module (720) and the detection data from the DMM module (600); The synchronous control unit (230) comprises a first comparator, a first switch tube, a logic gate component, and a second switch tube; the non-inverting input terminal of the first comparator is connected to a first voltage dividing branch; the inverting input terminal of the first comparator is connected to a first detection pin of the first four-pin sampling resistor (120); the control terminal of the first switch tube is connected to the output terminal of the first comparator; the high voltage terminal of the first switch tube is connected to the first input terminal of the logic gate component; the low voltage terminal of the first switch tube is connected to the reference voltage terminal; the second input terminal of the logic gate component is connected to the microprocessor (700); the output terminal of the logic gate component is connected to the control terminal of the second switch tube; the high voltage terminal of the second switch tube is connected to the control terminal of the single-way switch unit (210) and the control terminal of the multi-way selection switch unit (220); and the low voltage terminal of the second switch tube is connected to the reference voltage terminal.

2. The board test load circuit according to claim 1, characterized in that: The logic gate component is a NOR gate component.

3. The board test load circuit according to claim 1 or 2, characterized in that: The single-way switch unit (210) and the multi-way strobe switch unit (220) are integrated into the same relay.

4. The board card test load circuit according to claim 1, characterized in that, The first instrument amplifier module (400) comprises a first instrument amplifier, wherein a non-inverting input terminal of the first instrument amplifier is connected to a static connection terminal of the multi-way selection switch unit (220), and an inverting input terminal of the first instrument amplifier is connected to a second detection terminal of the second four-pin sampling resistor (130).

5. The board test load circuit according to claim 1 or 4, characterized in that: The gain coefficient of the first instrument amplification module (400) is 1.

6. The board test load circuit according to claim 1, characterized in that: The second instrument amplifier module (500) comprises a second instrument amplifier, a non-inverting input terminal of the second instrument amplifier is connected to the static connection terminal of the multi-way selection switch unit (220), and an inverting input terminal of the second instrument amplifier is connected to the second detection terminal of the second four-pin sampling resistor (130).

7. The board test load circuit according to claim 6, characterized in that: A gain selection unit (510) is connected to a gain configuration terminal of the second instrumentation amplifier, and an input terminal of the gain selection unit (510) is connected to the microprocessor (700).

8. The board card test load circuit according to claim 1, 6 or 7, characterized in that, The output end of the second instrument amplification module (500) is connected to a voltage stabilization unit.

9. A board card testing device, characterized in that, The board test load circuit comprises the board test load circuit according to any one of claims 1 to 8.

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