A current testing circuit

Abstract

This invention provides a current testing circuit, including a current regulation module, a main control module, and a detection module. The current regulation module provides operating current to the device under test (DUT). The sampling terminal of the detection module is connected to the sensor testing circuit to acquire the operating current flowing through the DUT and transmit the detection signal to the main control module. The main control module is configured to output a control signal to the current regulation module to selectively connect or disconnect the current regulation module, allowing multiple current regulation units to be connected to the test circuit in a preset combination. The module also stores the detection signal when it decreases or is lost. This embodiment of the invention achieves current regulation through the combined connection of multiple current regulation units, enabling rapid capture and recording of critical current values ​​when the sensor protection trips. It offers advantages such as high testing accuracy and strong dynamic adjustment capability.

Description

Technical Field

[0001] This utility model relates to the field of current detection technology, specifically to a current testing circuit. Background Technology

[0002] In electronic testing and product verification, it is necessary to evaluate the operating current of the equipment to confirm its performance and reliability. In order to accurately measure the current value of the equipment under the maximum load condition, that is, its maximum protection current, this test can determine whether the equipment has the ability to automatically cut off the output or reduce power consumption under abnormal conditions, thereby avoiding device damage or system failure due to overload. The above test is widely used in devices such as safety light curtains, safety door switches, temperature sensors, and pressure sensors.

[0003] However, existing testers often use resistors with fixed resistance values ​​as loads or offer only a few resistance values ​​to choose from when detecting the maximum protection current. Although existing testers can complete current detection, the adjustment range of the output current is very limited due to the single resistance value or limited number of resistors, and they cannot achieve small-step current increases.

[0004] In addition, different devices under test have different protection current settings. If the test is conducted by relying solely on a fixed resistor, it is often impossible to accurately scan the operating point of the device under test when it is close to the protection threshold, resulting in a large deviation in the test results. Utility Model Content

[0005] The purpose of this application is to provide a current testing circuit that has the advantages of realizing multiple different current outputs and meeting the testing requirements of different devices under test.

[0006] The technical solution of this utility model is as follows: A current testing circuit, comprising: The current regulation module includes multiple current regulation units, the power supply terminal of which is connected to an external power source. The main control module is electrically connected to the control terminals of the multiple current regulation units respectively; The detection module has its detection terminal electrically connected to the test circuit and its feedback terminal electrically connected to the main control module; wherein: The current regulation unit is used to provide operating current to the device under test; The sampling end of the detection module is connected in the sensor test circuit to obtain the operating current flowing through the device under test and transmit the detection signal corresponding to the operating current to the main control module. The main control module is configured to output a control signal to the current regulating unit to selectively turn the current regulating unit on or off, so that multiple current regulating units are connected to the test circuit in a preset combination, and to store the detection signal when the detection signal decreases or is lost.

[0007] Furthermore, the output current values ​​of the plurality of current regulation units form a current sequence, and adjacent current values ​​in the current sequence are configured to increase in steps.

[0008] Furthermore, the output current values ​​of the plurality of current regulation units form a current sequence, and adjacent current values ​​in the current sequence are configured to increase geometrically.

[0009] Furthermore, the current regulation unit includes an access control unit and a resistor unit. The controlled terminal of the access control unit is connected to the control terminal of the detection module. The controlled branch of the access control unit is connected in series with the resistor unit to form a current output path. One end of the current output path is connected to the device under test, and the other end of the current output path is connected to the external power supply.

[0010] Furthermore, the access control unit includes a first switch unit, a second switch unit, and a resistor R1. One end of the resistor R1 is connected to an external power supply, and the other end of the resistor R1 is connected to the controlled terminal of the first switch unit and the input terminal of the second switch unit. The input terminal of the first switch unit is connected to the external power supply, and the output terminal of the first switch unit is connected to the sensor under test through the resistor unit. The controlled terminal of the second switch unit is connected to the main control module, and the output terminal of the second switch unit is grounded.

[0011] Furthermore, the first switching unit includes a switching transistor Q1, and the second switching unit includes a switching transistor Q2, wherein the switching transistor Q1 is a P-channel MOSFET and the switching transistor Q2 is an N-channel MOSFET.

[0012] Furthermore, a sampling resistor R3 is provided between the input terminal of the first switching unit and the external power supply. The detection module includes a first sampling terminal and a second sampling terminal, which are respectively connected to the two ends of the sampling resistor R3.

[0013] Furthermore, a resistor R4 is provided between the output terminal and the controlled terminal of the second switching unit.

[0014] Furthermore, multiple current regulation units are connected in parallel, with their output terminals connected to the device under test and their power supply terminals connected to an external power source.

[0015] Furthermore, the main control module includes a main control unit and an IO expansion unit. The parallel output terminal of the IO expansion unit is electrically connected to the control terminals of the multiple current regulation units, and the serial input terminal of the IO expansion unit is electrically connected to the serial interface of the main control module.

[0016] The beneficial effects of this application are as follows: This utility model embodiment uses multiple current adjustment units connected in parallel, so that each current adjustment unit can be selectively connected to the test circuit as needed; the output current values ​​of each current adjustment unit form a current sequence in sequence, and can be configured to increase in steps or geometrically as required; by controlling the switching of the current adjustment units through the main control module, multiple different current outputs can be achieved, and the test current can be precisely adjusted to meet the test requirements of different devices under test. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a circuit structure block diagram of this utility model; Figure 2 This is a circuit structure block diagram of another embodiment of the present invention; Figure 3 This is a circuit diagram of yet another embodiment of the present invention; Figure 4 This is a circuit diagram of the detection module of this utility model; Figure 5 This is a partial circuit diagram of the current regulation module of this utility model; Figure 6 It corresponds Figure 5 Another part of the circuit diagram; Figure 7 This is a partial circuit diagram of the current regulation module in another embodiment of this utility model; Figure 8 It corresponds Figure 7 Another part of the circuit diagram; Figure 9 It corresponds Figure 7 and Figure 8 A circuit diagram of the detection module in the embodiment; Figure 10 This is a circuit diagram of the IO expansion unit of this utility model.

[0019] Figure label: 100. Current regulation module; 110. Current regulation unit; 111. Connection control unit; 111A. First switching unit; 111B. Second switching unit; 112. Resistor unit; 200. Main control module; 300. Detection module; 400. External power supply; 500. Device under test; 600, I / O expansion unit. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] In existing technologies, the maximum protection current test of sensor testers often uses a fixed-value resistor as the load, which limits the range of output current adjustment. Because the resistor value is singular or the number of options is limited, small-step current increases cannot be achieved. When testing different sensor models, the fixed resistor cannot cover a wide range of protection current thresholds, easily causing test deviations. For example, when testing temperature sensors and pressure sensors, the difference in their protection current can reach tens of milliamperes, and traditional testing devices cannot accurately capture the critical protection point.

[0025] To address the aforementioned issues, it is necessary to overcome the limitations of fixed resistor adjustment and establish a combinatorially adjustable current output mechanism. Analysis revealed that a single current source cannot meet the demands of multi-stage regulation, while parallel connection of multiple switchable current units can create a geometric or arithmetic current sequence. Further consideration was given to the need for real-time monitoring of current changes during testing, requiring the main control unit to dynamically adjust the current combination based on feedback signals. This led to a technical approach that utilizes multi-current unit combined output, real-time detection and feedback, and intelligent control adjustment.

[0026] Therefore, refer to Figure 1 This application proposes a current testing circuit, a current adjustment module 100 including multiple current adjustment units 110, the power supply terminal of each current adjustment unit 110 being connected to an external power supply 400; a main control module 200, electrically connected to the control terminals of the multiple current adjustment units 110 respectively; and a detection module 300, the detection terminal of which is electrically connected to the test circuit, and the feedback terminal of which is electrically connected to the main control module 200; wherein: the current adjustment units 110 are used to provide operating current to the device under test 500; the sampling terminal of the detection module 300 is connected to the sensor test circuit, used to acquire the operating current flowing through the device under test 500, and transmit the detection signal corresponding to the operating current to the main control module 200; the main control module 200 is configured to output control signals to the current adjustment units 110 to selectively turn the current adjustment units 110 on or off, so that the multiple current adjustment units 110 are connected to the test circuit in a preset combination, and to store the detection signal when the detection signal decreases or is lost.

[0027] In specific implementation, when the corresponding current adjustment unit 110 is turned on, it is connected to the test circuit and provides the corresponding current value. When the switching unit is turned off, the current adjustment unit 110 does not participate in the circuit operation. By controlling the opening and closing states of different current adjustment units 110, several different access combinations can be formed. Each access combination corresponds to a specific total current output value. In this way, the current output can be increased step by step according to the preset step mode, so as to achieve accurate scanning and determination of the maximum protection current of the device under test 500 with the cooperation of the detection module 300.

[0028] This embodiment of the invention uses multiple current adjustment units connected in parallel, allowing each unit to be selectively connected to the test circuit as needed. The output current values ​​of each current adjustment unit sequentially form a current sequence, which can be configured to increase in steps or geometrically as required. By controlling the switching of the current adjustment units through the main control module, multiple different current outputs can be achieved, precisely adjusting the test current to meet the testing needs of different devices under test.

[0029] It should be noted that, in specific implementation, the main control module 200 is a circuit system that includes sensor signal acquisition and the coordinated operation of various control execution components, including an embedded processor, sensor signal input interface, device component control signal output interface, and related electronic circuits.

[0030] It should also be noted that the external power supply 400 is not limited to a specific type. It can be a DC regulated power supply, such as an adjustable DC power supply used in laboratories; it can also be a DC output provided by a battery pack or battery management system; or it can be a DC power supply converted from AC power via a power adapter. Any power supply that can provide the current regulation module 100 with stable electrical energy matching the rated voltage of the device under test 500 can be used as the external power supply 400. The specific output capacity of the external power supply 400 can be determined according to the load requirements of the device under test 500 and its test circuit. For example, for sensors with smaller rated currents, a power supply with lower output power can be selected; for sensors with larger rated currents, a power supply with higher capacity can be selected. This method of power supply selection is a conventional design approach for those skilled in the art and can be implemented without creative effort.

[0031] In one embodiment, the device under test 500 may be various electronic devices or components such as safety light curtains, door switches, temperature sensors, pressure sensors, and current sensors.

[0032] This application further proposes that the output current values ​​of multiple current adjustment units 110 form a current sequence. The adjacent current values ​​in the current sequence are configured to increase in equal steps or geometrically. The current sequence refers to the numerical sequence formed by arranging the output current values ​​of multiple current adjustment units 110 according to a preset rule. Specifically, it can be achieved by setting resistor units 112 with different resistance values ​​or adjusting the switch control logic. The serialized current values ​​can cover a wider test range. Equal step increase means that the difference between two adjacent current values ​​remains constant. Specifically, it can be achieved by a linearly increasing resistor network or a current source with a fixed increment. Geometric increase means that two adjacent current values ​​have a fixed ratio relationship. Preferably, it increases by a ratio of 2 starting from 1mA. It can also be achieved by binary weighted resistors or exponential current amplifier circuits. The target current is obtained by the combination and selection of each weighted current so as to achieve a wide range of rapid approximation of the protection current limit of the device under test with the minimum resolution.

[0033] In one embodiment, the current regulation module 100 includes multiple current regulation units 110, and the output current value of each current regulation unit 110 is sequentially set to 1mA, 2mA, 3mA, 4mA, 5mA, etc., forming an equal step increment sequence. By controlling the connection of different current regulation units 110 through the main control module 200, multiple levels of equal step current output can be formed, for example, loading step by step in a fixed step of 1mA to realize fine scanning test of the device under test 500.

[0034] In another embodiment, the output current values ​​of the plurality of current regulating units 110 are sequentially set to 1mA, 2mA, 4mA, 8mA, 16mA, 32mA, 64mA, 128mA, etc., forming a geometrically increasing sequence starting from 1mA. By controlling the combination and selection of different current regulating units 110, a large number of discrete current levels can be formed over a wide range; for example, selecting only 1mA yields 1mA, selecting 1mA and 2mA yields 3mA, selecting 1mA and 4mA yields 5mA, selecting 1mA, 2mA, and 4mA yields 7mA, and so on, all of which can be obtained by superimposing several weighted currents.

[0035] In a preferred embodiment, there are eight current adjustment units 110, with output current values ​​of 1mA, 2mA, 4mA, 8mA, 16mA, 32mA, 64mA, and 128mA, respectively. The main control module 200 controls the on / off state of these eight current adjustment units 110, allowing them to be connected to the test circuit in different combinations: when only the first current adjustment unit 110 is on, the output current is 1mA; when the first and second units are on simultaneously, the output current is 3mA; when the first and third units are on, the output current is 5mA; and when all three units are on, the output current is 7mA. Since the output current of each current adjustment unit 110 is set in a geometrically increasing manner, the eight units can generate 255 non-zero current levels, with a maximum of 255mA.

[0036] Furthermore, this application does not limit the number of current adjustment units 110 to 8, but can be expanded to N according to the test range requirements. Under the condition of geometric increase and initial resolution of 1mA, those skilled in the art can adjust the value of N and the initial resolution according to the requirements without creative effort, so as to achieve a trade-off between test accuracy and range.

[0037] Compared with existing technologies, this solution, based on geometrically increasing weights starting from 1mA and a combined gating mechanism, covers a wide range of currents while maintaining a minimum resolution of 1mA, enabling precise capture of the current response of the device under test 500 in critical states, and significantly improving the accuracy and applicability of the test.

[0038] Furthermore, refer to Figures 2-3The current regulating unit 110 includes an access control unit 111 and a resistor unit 112. The controlled terminal of the access control unit 111 is connected to the control terminal of the detection module 300. The controlled branch of the access control unit 111 is connected in series with the resistor unit 112 to form a current output path. One end of the current output path is connected to the device under test 500, and the other end of the current output path is connected to the external power supply 400. The access control unit 111 is a component that controls the on / off state of the current path through an electrical signal. The resistor unit 112 is an element used to limit the output current value, and its resistance value determines the output current range of the current regulating unit 110.

[0039] In practical implementation, the access control unit 111 selectively turns on or off via control signals sent by the main control module 200, causing the corresponding resistor unit 112 to connect to or disconnect from the test circuit. When the access control unit 111 is on, the external power supply 400 provides operating current to the device under test 500 through the resistor unit 112; the detection module 300 collects the current signal flowing through the sensor in real time and feeds back the detection result to the main control module 200. The main control module 200 dynamically adjusts the state of the access control unit 111 according to the feedback signal, and achieves multi-level adjustment of the current output by combining different resistor units 112.

[0040] Furthermore, the access control unit 111 includes a first switch unit 111A, a second switch unit 111B, and a resistor R1. One end of the resistor R1 is connected to an external power supply 400, and the other end of the resistor R1 is connected to the controlled terminal of the first switch unit 111A and the input terminal of the second switch unit 111B. The input terminal of the first switch unit 111A is connected to the external power supply 400, and the output terminal of the first switch unit 111A is connected to the device under test 500 through the resistor unit 112. The controlled terminal of the second switch unit 111B is connected to the main control module 200, and the output terminal of the second switch unit 111B is grounded. The first switch unit 111A is configured to be turned on when the controlled terminal is low, and the second switch unit 111B is configured to be turned on when the controlled terminal is high.

[0041] In practical implementation, when the main control module 200 outputs a high-level signal to the controlled terminal of the second switch unit 111B, the second switch unit 111B conducts, forming a loop between resistor R1 and ground. At this time, the controlled terminal of the first switch unit 111A is pulled low, triggering its conduction state. The current from the external power supply 400 flows sequentially through the first switch unit 111A and resistor unit 112 to the device under test 500, forming a working current path. When the main control module 200 stops outputting the high-level signal, the second switch unit 111B turns off, the controlled terminal of the first switch unit 111A returns to the high-level state, and the current path is cut off. By controlling the on / off timing of the second switch unit 111B, the current regulation unit 110 can be connected and disconnected in stages, solving the problem of insufficient current regulation accuracy caused by switch control delay in traditional test circuits. This achieves rapid and accurate control of the sensor's working current, ensuring that the current output can be cut off in time when the detection signal is abnormal, preventing the sensor from being damaged by overcurrent.

[0042] In a preferred embodiment, the first switching unit 111A is a switching transistor Q1, which is a P-channel MOSFET. Specifically, the gate of the switching transistor Q1 serves as the controlled terminal, receiving potential control from the resistor R1; the source of the switching transistor Q1 serves as the input terminal, electrically connected to the external power supply 400; and the drain of the switching transistor Q1 serves as the output terminal, connected to the device under test 500 via the resistor unit 112. By controlling the gate potential of the switching transistor Q1, the first switching unit 111A can be turned on and off.

[0043] Preferably, the second switching unit 111B is a switching transistor Q2, which is an N-channel MOSFET, and its gate is also used as a controlled terminal and electrically connected to the main control module 200.

[0044] During operation, when the main control module 200 outputs a high-level signal to the gate of the N-channel MOSFET, the N-channel MOSFET turns on, causing the gate of the P-channel MOSFET to be pulled low to ground potential. At this time, the P-channel MOSFET turns on, and the external power supply 400 provides operating current to the device under test 500 through the resistor unit 112. When the main control module 200 outputs a low-level signal, the N-channel MOSFET turns off, and the gate potential of the P-channel MOSFET is pulled up to the power supply voltage, thereby turning off the current output path. By alternately controlling the conduction states of the two MOSFETs, high-precision on / off operation of the current regulation unit 110 can be achieved.

[0045] In one embodiment, a sampling resistor R3 is provided between the input terminal of the first switching unit 111A and the external power supply 400. The detection module 300 includes a first sampling terminal and a second sampling terminal, which are respectively connected to the two ends of the sampling resistor R3.

[0046] The sampling resistor R3 is a component connected in series in the current path to acquire information about current changes. By measuring the voltage difference across resistor R3, the current value flowing through that branch can be directly reflected. The first sampling terminal and the second sampling terminal refer to the interfaces in the detection module 300 used to connect the two ends of the sampling resistor. Specifically, they can be implemented using a differential input circuit or a high-precision ADC channel. By acquiring the potential difference across the resistor, the influence of common-mode interference on measurement accuracy can be eliminated.

[0047] In practical implementation, when the current regulating unit 110 is working, the current output by the external power supply 400 flows through the sampling resistor R3 and the first switching unit 111A to form a loop. The detection module 300 acquires the voltage signal across the sampling resistor R3 in real time through the first sampling terminal and the second sampling terminal, and calculates the actual operating current flowing through the device under test 500 through the built-in function of the detection module 300.

[0048] Preferred, refer to Figure 4 Preferably, the detection unit U8 has a shunt voltage input port, wherein VIN+ and VIN- are used to receive voltage signals across the sampling resistor, the first sampling end corresponds to the VIN+ port of the detection unit U8, and the second sampling end corresponds to the VIN- port of the detection unit U8, and are respectively connected to the two ends of the sampling resistor R3, for real-time detection of the operating current flowing through the device under test 500, thus solving the problem of misjudgment caused by insufficient sampling accuracy in traditional testing methods.

[0049] In a preferred embodiment, the detection unit U8 can be an INA226 bidirectional current and power monitor for high and low side measurement, or other detection units with the same or similar functions as the INA226. As long as it can detect the voltage across the sampling resistor and calculate the operating current flowing through the device under test 500, it can be used as the detection unit.

[0050] Furthermore, a resistor R4 is provided between the output terminal and the controlled terminal of the second switching unit 111B to prevent the switching device from entering an uncertain state when there is no driving signal, thereby improving the control reliability of the current regulating unit 110.

[0051] Reference Figures 5-6 This application further proposes a parallel arrangement of multiple current adjustment units 110, with their output terminals connected to the current loop port black of the device under test 500 and their power supply terminals connected to an external power supply 400, thereby improving the flexibility and reliability of the test circuit.

[0052] Reference Figures 7-8 , Figures 7-8 This is another embodiment of the current regulation module 100 of this utility model.

[0053] Reference Figure 9 , Figure 9 It shows the relationship with Figures 7-8 Another specific implementation of the detection module 300 that is matched with the current regulation module 100 shown.

[0054] Furthermore, refer to Figure 10 The main control module 200 includes a main control unit and an I / O expansion unit 600. The parallel output terminals of the I / O expansion unit 600 are electrically connected to the control terminals of multiple current regulation units 110, and the serial input terminals of the I / O expansion unit 600 are electrically connected to the serial interface of the main control module 200. It receives commands from the main control unit via serial data and converts them into multiple parallel control signals for output, thereby reducing the number of physical interfaces directly connected to the main control unit.

[0055] During operation, the main control unit sends control commands to the I / O expansion unit 600 via a serial interface. These commands contain the switching status configuration information for multiple current regulation units 110. The I / O expansion unit 600 converts the serial data into parallel output signals and transmits each signal to the corresponding control terminal of the current regulation unit 110. In this way, the main control unit only needs to occupy a small number of communication interfaces to achieve independent control of multiple current regulation units 110, thereby dynamically adjusting the combination of current regulation units 110 connected to the circuit during testing.

[0056] In a preferred embodiment, when there are eight current regulation units 110, the I / O expansion unit 600 can be an 8-bit serial-in parallel-out shift register (SN74HC595). This device has a tri-state output register structure and can receive control commands from the main control unit via a serial interface, converting them into eight parallel control signal outputs to drive the control terminals of the eight current regulation units 110 respectively. Furthermore, when the number of current regulation units 110 is other values, I / O expansion units 600 with matching bit widths can be selected, or multiple I / O expansion units 600 can be cascaded. Those skilled in the art can select a suitable I / O expansion scheme based on the number of current regulation units 110 without any inventive effort.

[0057] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the corresponding claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the corresponding claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0058] The above is only used to illustrate the technical solution of this utility model and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. A current testing circuit, characterized in that, include: The current regulation module (100) includes multiple current regulation units (110), the power supply terminal of which is connected to an external power supply (400). The main control module (200) is electrically connected to the control terminals of the multiple current regulating units (110); A detection module (300) is provided, wherein the detection terminal of the detection module (300) is electrically connected to the test circuit, and the feedback terminal of the detection module (300) is electrically connected to the main control module (200); wherein: The current regulating unit (110) is used to provide operating current to the device under test (500); The sampling end of the detection module (300) is connected to the sensor test circuit to obtain the working current flowing through the device under test (500) and transmit the detection signal corresponding to the working current to the main control module (200). The main control module (200) is configured to output control signals to the current regulating unit (110) to selectively turn the current regulating unit (110) on or off, to connect multiple current regulating units (110) to the test circuit in a preset combination, and to store the detection signal when the detection signal decreases or is lost.

2. The current testing circuit according to claim 1, characterized in that, The output current values ​​of the plurality of current regulation units (110) form a current sequence, wherein adjacent current values ​​in the current sequence are configured to increase in steps.

3. The current testing circuit according to claim 1, characterized in that, The output current values ​​of the plurality of current regulation units (110) form a current sequence, wherein adjacent current values ​​in the current sequence are configured to increase geometrically.

4. The current testing circuit according to claim 2 or 3, characterized in that, The current regulation unit (110) includes an access control unit (111) and a resistor unit (112). The controlled end of the access control unit (111) is connected to the control end of the detection module (300). The controlled branch of the access control unit (111) is connected in series with the resistor unit (112) to form a current output path. One end of the current output path is connected to the device under test (500), and the other end of the current output path is connected to the external power supply (400).

5. The current testing circuit according to claim 4, characterized in that, The access control unit (111) includes a first switch unit (111A), a second switch unit (111B), and a resistor (R1). One end of the resistor (R1) is connected to an external power supply (400), and the other end of the resistor (R1) is connected to the controlled terminal of the first switch unit (111A) and the input terminal of the second switch unit (111B). The input terminal of the first switch unit (111A) is connected to the external power supply (400), and the output terminal of the first switch unit (111A) is connected to the device under test (500) through the resistor unit (112). The controlled terminal of the second switch unit (111B) is connected to the main control module (200), and the output terminal of the second switch unit (111B) is grounded.

6. The current testing circuit according to claim 5, characterized in that, The first switching unit (111A) includes a switching transistor (Q1), and the second switching unit (111B) includes a switching transistor (Q2). The switching transistor (Q1) is a P-channel MOSFET, and the switching transistor (Q2) is an N-channel MOSFET.

7. The current testing circuit according to claim 5, characterized in that, A sampling resistor (R3) is provided between the input terminal of the first switching unit (111A) and the external power supply (400). The detection module (300) includes a first sampling terminal and a second sampling terminal, which are respectively connected to the two ends of the sampling resistor (R3).

8. The current testing circuit according to claim 5, characterized in that, A resistor (R4) is also provided between the output terminal and the controlled terminal of the second switching unit (111B).

9. The current testing circuit according to claim 2 or 3, characterized in that, Multiple current regulating units (110) are connected in parallel, with their output terminals connected to the device under test (500) and their power supply terminals connected to an external power supply (400).

10. The current testing circuit according to claim 2 or 3, characterized in that, The main control module (200) includes a main control unit and an IO expansion unit. The parallel output terminal of the IO expansion unit is electrically connected to the control terminals of the multiple current regulation units (110), and the serial input terminal of the IO expansion unit is electrically connected to the serial interface of the main control module (200).

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