Board card test load circuit and equipment

Abstract

The invention discloses a board card test load circuit and equipment, and the circuit comprises a regulation and sampling module, a synchronous switch module, a feedback comparison module, a first instrument amplification module, a second instrument amplification module, and a microprocessor. A first four-pin sampling resistor and a second four-pin sampling resistor are configured on a large-current branch, the measurement precision can be improved, a microprocessor controls synchronous switching of a single-path switch unit and a multi-path gating switch unit through a synchronous control unit of a synchronous switch module in measurement so as to adapt to large-current and small-current test application scenes, and the measurement precision is improved. The microprocessor performs signal acquisition through the first instrument amplification module and the second instrument amplification module to realize feedback adjustment, and adjusts control signals of the current regulation and control unit and the synchronous control unit according to error calibration data stored in the storage module and detection data from the DMM module. Precise control of the load pulling current is realized, and the test precision is improved.

Description

Technical Field

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

[0002] A mobile power bank (such as a power bank) is a power product used to power electronic mobile devices. With the continuous development of technology, the charging efficiency requirements for electronic mobile devices are getting higher and higher, resulting in the continuous increase in the load current of mobile power banks. In order to ensure the safety of the product, the mainboard of the mobile power bank needs to be tested during the production process. However, the testing equipment of related technologies is difficult to meet the testing requirements of the increasing load current of mobile power banks. Customized testing equipment is required for high-current mobile power banks, which has high testing costs. In addition, the customized equipment has low testing accuracy for mobile power banks with small load currents and is not very versatile. Summary of the invention

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

[0004] On the one hand, an embodiment of the present invention provides a board test load circuit, including: A control and sampling module is arranged on a large current branch, the control and sampling module comprises a current control unit, a first four-pin sampling resistor and a second four-pin sampling resistor, the high voltage end of the current control unit is used as a load output end, the low voltage end of the current control 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, and the second main pin of the second four-pin sampling resistor is connected to the reference voltage end; A synchronous switch module, comprising a single-way switch unit, a multi-way gate switch unit and a synchronous control unit, wherein two ends of the single-way switch unit are respectively connected to the large current branch and connected in parallel to the first four-pin sampling resistor, a first movable connection end of the multi-way gate switch is connected to a first detection pin of the second four-pin sampling resistor, a second movable connection end of the multi-way gate switch is connected to a second detection pin of the second four-pin sampling resistor, a first input end of the synchronous control unit is connected to a first detection pin of the first four-pin sampling resistor, and an output end of the synchronous control unit is connected to a control end of the single-way switch unit and a control end of the multi-way gate switch unit; A feedback comparison module, the output end of which is connected to the control end of the current control unit; A first instrument amplifier module, wherein a first input end is connected to the static connection end of the multi-way selection switch unit, a second input end of the first instrument amplifier module is connected to the second detection pin of the second four-pin sampling resistor, and an output end of the first instrument amplifier module is connected to the second input end of the feedback comparison module; A second instrument amplifier module, wherein a first input end is connected to the static connection end of the multi-way selection switch unit, a second input end of the second instrument amplifier module is connected to the second detection pin of the second four-pin sampling resistor, and an output end of the second instrument amplifier module is used to connect to a DMM module; A microprocessor is connected to a DAC module and a storage module. The microprocessor is connected to a first input terminal of the feedback comparison module through the DAC module. The microprocessor is also connected to the DMM module and a second input terminal of the synchronization control unit. The microprocessor is used to adjust control signals of the current control unit and the synchronization control unit according to error calibration data stored in the storage module and detection data from the DMM module.

[0005] According to some embodiments of the present invention, the synchronous control unit includes a first comparator, a first switch tube, a logic gate component and a second switch tube, the non-inverting input end of the first comparator is connected to a first voltage divider branch, the inverting input end of the first comparator is connected to the first detection pin of the first four-pin sampling resistor, the control end of the first switch tube is connected to the output end of the first comparator, the high-voltage end of the first switch tube is connected to the first input end of the logic gate component, the second input end of the logic gate component is connected to the microprocessor, the output end of the logic gate component is connected to the control end of the second switch tube, and the high-voltage end of the second switch tube is connected to the control end of the single-way switch unit and the control end of the multi-way selection switch unit.

[0006] According to some embodiments of the present invention, the logic gate component is a NOR gate component.

[0007] According to some embodiments of the present invention, the single-way switch unit and the multi-way gate switch unit are integrated into the same relay.

[0008] According to some embodiments of the present invention, the first instrument amplification module includes a first instrument amplifier, a non-inverting input terminal of the first instrument amplifier is connected to the static connection terminal of the multi-way selection switch unit, and an inverting input terminal of the first instrument amplifier is connected to the second detection terminal of the second four-pin sampling resistor.

[0009] According to some embodiments of the present invention, a gain coefficient of the first instrument amplifier module is 1.

[0010] According to some embodiments of the present invention, the second instrument amplification module includes 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, and an inverting input terminal of the second instrument amplifier is connected to the second detection terminal of the second four-pin sampling resistor.

[0011] According to some embodiments of the present invention, a gain configuration terminal of the second instrumentation amplifier is connected to a gain selection unit, and an input terminal of the gain selection unit is connected to the microprocessor.

[0012] According to some embodiments of the present invention, the output end of the second instrument amplifier module is connected to a voltage stabilizing unit.

[0013] On the other hand, an embodiment of the present invention provides a board test device, including the above-mentioned board test load circuit.

[0014] The embodiments of the present invention have at least the following beneficial effects: A current control unit is configured on the large current branch to achieve the control of the load current. A first four-pin sampling resistor and a second four-pin sampling resistor are configured on the large current branch to improve the measurement accuracy. During the measurement process, the microprocessor controls the synchronous switching of the single-channel switch unit and the multi-channel selection switch unit through the synchronous control unit of the synchronous switch module to adapt to the test application scenarios of large current and small current, and respectively collects signals through the first instrument amplification module and the second instrument amplification module to achieve feedback regulation. The microprocessor also adjusts the control signals of the current control 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 precise control of the load current, which is conducive to improving the test accuracy.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 It is a principle block diagram of a board test load circuit according to an embodiment of the present invention; Figure 2 for Figure 1 The circuit schematic diagram of the control and sampling module of the board test load circuit shown; Figure 3 for Figure 1 The circuit schematic diagram of the feedback comparison module of the board test load circuit shown; Figure 4 for Figure 1The circuit schematic diagram of the synchronous control unit of the board test load circuit shown; Figure 5 for Figure 1 The circuit schematic diagram of the first instrument amplifier module of the board test load circuit shown; Figure 6 for Figure 1 The circuit schematic diagram of the second instrument amplifier module of the board test load circuit shown; Figure 7 for Figure 1 The circuit schematic diagram of the gain selection unit of the board test load circuit is shown.

[0017] Reference numerals: Control and sampling module 100, large current branch 101, current control unit 110, first four-pin sampling resistor 120, second four-pin sampling resistor 130, synchronous switch module 200, single-way switch unit 210, multi-way selection switch unit 220, synchronous control unit 230, feedback comparison module 300, first instrument amplifier module 400, second instrument amplifier module 500, gain selection unit 510, DMM module 600, microprocessor 700, DAC module 710, storage module 720. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0019] In the description of the present invention, "several" means one or more, "multiple" means more than two, greater than, less than, and exceeding are understood as not including the number itself, and "above", "below", and "within" are understood as including the number itself. If there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0020] In the description of the present invention, unless otherwise clearly defined, words such as “setting”, “installation” and “connection” should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0021] The test items of mobile power supply are related to the load current. Stable and accurate load current control is conducive to improving the accuracy of the test. In the related technology, although customized test equipment for high current test scenarios can also be applied to small current test scenarios, the control accuracy of the load current is low, resulting in low test accuracy and unable to meet high-precision test requirements, making the customized test equipment not very versatile.

[0022] This embodiment discloses a board test device, including a board test load circuit. Figure 1 The board test load circuit includes a control and sampling module 100, a synchronous switch module 200, a feedback comparison module 300, a first instrument amplifier module 400, a second instrument amplifier module 500 and a microprocessor 700.

[0023] The control and sampling module 100 is arranged on the large current branch 101. The control and sampling module 100 includes a current control unit 110, a first four-pin sampling resistor 120 and a second four-pin sampling resistor 130. The high voltage end of the current control unit 110 is used as a load output end, the low voltage end of the current control 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, and the second main pin of the second four-pin sampling resistor 130 is connected to the reference voltage end.

[0024] The synchronous switch module 200 includes a single-way switch unit 210, a multi-way gate switch unit 220 and a synchronous control unit 230. The two ends of the single-way switch unit 210 are respectively connected to the large current branch 101 and connected in parallel to the first four-pin sampling resistor 120. The first moving connection end of the multi-way gate switch is connected to the first detection pin of the second four-pin sampling resistor 130, the second moving connection end of the multi-way gate switch is connected to the second detection pin of the second four-pin sampling resistor 130, 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 output end of the synchronous control unit 230 is connected to the control end of the single-way switch unit 210 and the control end of the multi-way gate switch unit 220.

[0025] The output end of the feedback comparison module 300 is connected to the control end of the current control unit 110, the first input end of the first instrument amplifier module 400 is connected to the static connection end of the multi-way selection switch unit 220, the second input end of the first instrument amplifier module 400 is connected to the second detection pin of the second four-pin sampling resistor 130, and the output end of the first instrument amplifier module 400 is connected to the second input end of the feedback comparison module 300; the first input end of the second instrument amplifier module 500 is connected to the static connection end of the multi-way selection switch unit 220, the second input end of the second instrument amplifier module 500 is connected to the second detection pin of the second four-pin sampling resistor 130, and the output end of the second instrument amplifier module 500 is used to connect to the DMM module 600, DMM is a digital multimeter.

[0026] The microprocessor 700 is connected to a DAC module 710 and a storage module 720. The microprocessor 700 is connected to a first input terminal of the feedback comparison module 300 through the DAC module 710. The microprocessor 700 is also connected to a second input terminal of the DMM module 600 and the synchronization control unit 230. 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.

[0027] In order to meet the high-precision test performance, this embodiment is based on the control concept of feedback regulation to accurately regulate the load current output to the load (such as a mobile power supply).

[0028] Please refer to Figure 2, the current control unit 110 is used to control the load current flowing through the large current branch 101. For example, the current control unit 110 can use a field effect transistor, or an integrated chip with a current control function. The large current branch 101 can allow a larger load current, so as to be compatible with large current and small current test scenarios. Among them, the implementation of the large current branch 101 can be achieved by laying out a wider line in the circuit layout. For example, if the designed rated current is 4A, the wiring is carried out according to the line width of 5A overcurrent. However, as the line width increases, the line resistance of the line will also affect the measurement of current or voltage. If a conventional chip resistor with only two terminals is used as a sampling resistor, it is difficult to eliminate the influence of the power supply voltage and the wire resistance on the measurement results. In the design process, attempts are made to reduce the influence of the aforementioned factors on the measurement results through circuit wiring techniques, but the measurement results still cannot meet the expected accuracy requirements. After continuous experiments and empirical analysis, the use of four-pin sampling resistors (such as the first four-pin sampling resistor 120 and the second four-pin sampling resistor 130) as the sampling resistors of the large current branch 101 helps to improve the measurement accuracy. It should be known that the four-pin sampling resistor, also called the four-wire resistor, is a special type of resistor that plays a role in accurately measuring the resistance value in the circuit. The four-pin resistor adopts 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, ensure the accuracy of the measurement value, and is suitable for high-precision measurement application scenarios.

[0029] In addition, the resistance 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-pin sampling resistor 120, the first four-pin sampling resistor 120 can be selectively connected or disconnected, thereby adjusting the total resistance of the sampling resistor on the large current branch 101, so that the function of using a large resistor to measure a small current and a small resistor to measure a large current can be achieved, which is conducive to improving the measurement accuracy in the small current scenario, and thus compatible with the test scenarios of large current and small current.

[0030] Please refer to Figure 2 The sampling signal collected by the sampling resistor on the large current branch 101 is used for feedback regulation, wherein the sampling signal is divided into two paths, the first sampling signal is fed back to the feedback comparison module 300, and the circuit schematic diagram of the feedback comparison module 300 is as shown in Figure 3As shown, the feedback comparison module 300 has a first input terminal and a second input terminal, and the first input terminal of the feedback comparison module 300 is used to receive a first control signal (such as the label I_E_Load_SET) output by the microprocessor 700, wherein the first control signal output by the microprocessor 700 is output to the first input terminal of the feedback comparison module 300 after being converted by the DAC module 710, and the second input terminal of the feedback comparison module 300 is used to receive a first sampling signal (such as the label E_LOAD_FB), so that the first control signal and the first sampling signal are compared and processed by the feedback comparison module 300, and then the current control unit 110 is controlled by comparing the output result, so as to realize the internal feedback control of the circuit. The second sampling signal is output to the DMM module 600 through the second instrument amplifier module 500, wherein the DMM module 600 can be a built-in module or an external module. Considering the user's habit of observing the measurement results from different dimensions (or using different devices) in actual application scenarios, this embodiment takes the external DMM module 600 as an example. The DMM module 600 processes the data and outputs the measurement results to the microprocessor 700. The microprocessor 700 adjusts the first control signal for controlling the current control unit 110 according to the error calibration data stored in the storage module 720 and the detection data from the DMM module 600, so as to realize the external feedback control of the circuit. Through the coordination of internal feedback control and external feedback control, it is possible to realize the rapid dynamic control of the load current inside the circuit, and also to realize the real-time monitoring and feedback control of the load current outside the circuit, thereby improving the accuracy of the load current control, and further improving the accuracy of the test.

[0031] 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 the multiple current data (output data) output by the microprocessor 700 is measured by the DMM module 600, and the error calibration data is determined according to the output data and the detection data. The error calibration data includes a calibration coefficient and a deviation value, and there is a linear relationship between the calibrated signal (i.e., the first control signal) and the original signal, such as the calibrated signal = calibration coefficient × original signal + deviation value. The original signal to be output by the microprocessor 700 is calibrated by the error calibration data, which can improve the accuracy of the output signal, and the output signal of the microprocessor 700 is adjusted in real time according to the feedback signal measured by the DMM module 600, further improving the accuracy of the load current regulation.

[0032] It is worth mentioning that the first instrument amplifier module 400 and the second instrument amplifier module 500 are gain amplifier modules constructed based on an instrument amplifier. The instrument amplifier has high precision and small error, can amplify and measure tiny signals, and can maintain the stability of the amplifier circuit and reduce the influence of temperature drift and noise. The instrument amplifier has a low background noise and can reduce noise interference in the signal. In addition, it has a filtering function for the input signal and can eliminate noise and clutter. The first instrument amplifier module 400 and the second instrument amplifier module 500 constructed based on the instrument amplifier are suitable for high-precision measurement circuits.

[0033] 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-way switch unit 210 and the control end of the multi-way selection 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 performed according to the feedback signal of the large current branch 101 and the output signal of the microprocessor 700, so as to realize flexible and accurate change of the sampling resistor on the large current branch 101, which is conducive to improving the accuracy of detection.

[0034] A current control unit 110 is configured on the large current branch 101 to achieve the control of the load current. A first four-pin sampling resistor 120 and a second four-pin sampling resistor 130 are configured on the large current branch 101 to improve the measurement accuracy. During the measurement process, the microprocessor 700 controls the synchronous switching of the single-way switch unit 210 and the multi-way selection switch unit 220 through the synchronous control unit 230 of the synchronous switch module 200 to adapt to the test application scenarios of large current and small current, and respectively performs signal acquisition through the first instrument amplifier module 400 and the second instrument amplifier module 500 to achieve feedback regulation. The microprocessor 700 also adjusts the control signals of the current control 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 load current, which is conducive 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-way switch unit 210, the multi-way selection switch unit 220, the first instrument amplifier module 400, the second instrument amplifier module 500, the DMM module 600, the microprocessor 700 and the storage module 720 form an organic and complete feedback regulation network, and together achieve high-precision control of the load current, thereby improving the test accuracy.

[0035] Please refer to Figure 4The synchronization control unit 230 includes a first comparator (as indicated by the mark U1800B), a first switch tube (as indicated by the mark Q1802), a logic gate component (as indicated by the mark U1805) and a second switch tube (as indicated by the mark Q1801). The non-inverting input end of the first comparator is connected to a first voltage dividing branch, such as a voltage dividing branch composed of a resistor R1835 and a resistor R1836. The inverting input end of the first comparator is connected to the first detection pin of the first four-pin sampling resistor 120. The control end of the first switch tube is connected to the output end of the first comparator. The high-voltage end of the first switch tube is connected to the first input end of the logic gate component (as indicated by the mark E_Load_RANGE_1). The second input end of the logic gate component (as indicated by the mark E_Load_RANGE_2) is connected to the microprocessor 700. The output end of the logic gate component is connected to the control end of the second switch tube. The high-voltage end of the second switch tube is connected to the control end of the single-way switch unit 210 and the control end of the multi-way 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, and the first comparator compares the sampling signal from the first four-pin sampling resistor 120 with the voltage division signal of the first voltage division 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 switch tube, so as to control the conduction and cutoff of the first switch tube, and then provide the 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 switch tube according to the processing result, and then synchronously controls the single-way switch unit 210 and the multi-way gate switch unit 220, so as to realize the self-locking of the single-way switch unit 210 and the multi-way gate switch unit 220 under the small current state. Among them, the logic gate component is an NOR gate component. In other application examples, the logic gate component can also adopt an OR gate component, an XOR gate component or an XOR gate component, but the circuit structure needs to be adaptively adjusted.

[0036] Please refer to Figure 2, the single-way switch unit 210 and the multi-way gate switch unit 220 are integrated into the same relay (as indicated by the mark K1800), wherein the 6th and 7th pins of the relay are used as the two connection ends of the single-way switch unit 210, the 3rd pin of the relay is used as the static connection end of the multi-way gate switch unit 220, and the 2nd and 4th pins of the relay are used as the first dynamic connection end and the second dynamic connection end of the multi-way gate switch unit 220 respectively. In the state of large current, the 6th and 7th pins of the relay are turned on, 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 switch tube, the second switch tube is turned on to make the relay attract, 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 switch tube and the logic gate component.

[0037] Please refer to Figure 5 The first instrument amplifier module 400 includes a first instrument amplifier (as indicated by the mark U1803), the in-phase input terminal of the first instrument amplifier is connected to the static connection terminal of the multi-way selection switch unit 220, and the connection node is indicated by the mark E_LOAD_SNS_P. The inverting input terminal of the first instrument amplifier is connected to the second detection terminal of the second four-pin sampling resistor 130, and the connection node is indicated by the mark E_LOAD_SNS_N. The first instrument amplifier module 400 can feed back the current signal on the large current path to the feedback comparison module 300. Compared with the conventional feedback resistor, the sampling accuracy of the first instrument amplifier is higher, and common-mode interference can be eliminated. It is worth mentioning that the large current branch 101 has a high temperature during operation, and the current control unit 110 needs to be heat-dissipated and thermally managed. In addition, a higher temperature working environment is prone to cause thermal noise and drift in the performance parameters of components. The gain coefficient of the first instrument amplifier module 400 is 1, which can increase the input resistance, reduce the output resistance, play a buffering role, and eliminate common-mode interference caused by factors such as temperature and electromagnetic interference, suppress zero-point drift, and improve the reliability of circuit operation.

[0038] Please refer to Figure 6 The second instrument amplifier module 500 includes a second instrument amplifier, the in-phase input terminal of the second instrument amplifier is connected to the static connection terminal of the multi-way selection switch unit 220, and the connection node is shown as the label E_LOAD_SNS_P. The inverting input terminal of the second instrument amplifier is connected to the second detection terminal of the second four-pin sampling resistor 130, and the connection node is shown as the label E_LOAD_SNS_N. The second instrument amplifier has the characteristics of high common mode rejection ratio, high input impedance, low noise, low linear error, low offset drift, and flexible gain setting. In addition, please refer to Figure 6 and Figure 7 , the gain configuration terminal of the second instrumentation amplifier (such as Figure 6 A gain selection unit 510 is connected to the microprocessor 700 (as shown by GAIN_G1 and GAIN_G2 in the figure). 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 actual application requirements to amplify the small current signal, thereby improving the accuracy of small current signal detection.

[0039] Please refer to Figure 6 In order to further improve the stability of the circuit operation, the output end of the second instrument amplifier module 500 is connected with a voltage stabilizing unit, such as a voltage stabilizing diode indicated by the mark D1800, which can stabilize the output voltage signal and improve the stability of the input signal of the DMM module 600, thereby improving the accuracy and precision of the detection. Among them, the mark E_LOAD_CURRENT is the connection end connected to the DMM module 600.

[0040] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A board test load circuit, characterized in that: include: A control and sampling module (100) is arranged on a large current branch (101), the control and sampling module (100) comprising a current control unit (110), a first four-pin sampling resistor (120) and a second four-pin sampling resistor (130), the high voltage end of the current control unit (110) being used as a load output end, the low voltage end of the current control unit (110) being connected to a first main pin of the first four-pin sampling resistor (120), the second main pin of the first four-pin sampling resistor (120) being connected to a first main pin of the second four-pin sampling resistor (130), and the second main pin of the second four-pin sampling resistor (130) being connected to a reference voltage end; A synchronous switch module (200), comprising a single-way switch unit (210), a multi-way gate switch unit (220) and a synchronous control unit (230), wherein two ends of the single-way switch unit (210) are respectively connected to the large current branch (101) and connected in parallel to the first four-pin sampling resistor (120), a first movable connection end of the multi-way gate switch is connected to a first detection pin of the second four-pin sampling resistor (130), a second movable connection end of the multi-way gate switch is connected to a second detection pin of the second four-pin sampling resistor (130), a first input end of the synchronous control unit (230) is connected to a first detection pin of the first four-pin sampling resistor (120), and an output end of the synchronous control unit (230) is connected to a control end of the single-way switch unit (210) and a control end of the multi-way gate switch unit (220); A feedback comparison module (300), the output end of which is connected to the control end of the current control unit (110); A first instrument amplifier module (400), wherein a first input end is connected to a static connection end of the multi-way selection switch unit (220), a second input end of the first instrument amplifier module (400) is connected to a second detection pin of the second four-pin sampling resistor (130), and an output end of the first instrument amplifier module (400) is connected to a second input end of the feedback comparison module (300); A second instrument amplifier module (500), wherein a first input end is connected to a static connection end of the multi-way selection switch unit (220), a second input end of the second instrument amplifier module (500) is connected to a second detection pin of the second four-pin sampling resistor (130), and an output end of the second instrument amplifier module (500) is used to connect to a DMM module (600); A microprocessor (700) is connected to a DAC module (710) and a storage module (720); the microprocessor (700) is connected to a first input terminal of the feedback comparison module (300) via the DAC module (710); the microprocessor (700) is also connected to the DMM module (600) and a second input terminal of the synchronization control unit (230); the microprocessor (700) is used to adjust control signals of the current control unit (110) and the synchronization control unit (230) according to error calibration data stored in the storage module (720) and detection data from the DMM module (600).

2. The board test load circuit according to claim 1, characterized in that: The synchronous control unit (230) comprises a first comparator, a first switch tube, a logic gate component and a second switch tube, wherein the non-inverting input end of the first comparator is connected to a first voltage dividing branch, the inverting input end of the first comparator is connected to a first detection pin of the first four-pin sampling resistor (120), the control end of the first switch tube is connected to the output end of the first comparator, the high voltage end of the first switch tube is connected to the first input end of the logic gate component, the second input end of the logic gate component is connected to the microprocessor (700), the output end of the logic gate component is connected to the control end of the second switch tube, and the high voltage end of the second switch tube is connected to the control end of the single-way switch unit (210) and the control end of the multi-way selection switch unit (220).

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

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

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

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

7. The board test load circuit according to claim 1, characterized in that: The second instrument amplifier module (500) comprises a second instrument amplifier, the 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 the inverting input terminal of the second instrument amplifier is connected to the second detection terminal of the second four-pin sampling resistor (130).

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

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

10. A board test device, characterized in that: It comprises the board test load circuit as claimed in any one of claims 1 to 9.

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