Test circuit and test method

Abstract

This invention provides a test circuit and test method. The test circuit includes: a module under test (DUT) providing the device under test; a pulse drive module for switching the DUT on and off based on a pulse signal and a comparison result; a current detection module for detecting the conduction current of the DUT and obtaining a detection voltage; a constant current control module for constant current control of the conduction current based on the comparison result of the detection voltage and a reference voltage, and adjusting the conduction current by adjusting the reference voltage; an overcurrent drive module for generating a synchronous turn-on signal based on the pulse signal and generating an auxiliary turn-off signal when the detection voltage is greater than a threshold voltage; an auxiliary switch module for turning on based on the synchronous turn-on signal and turning off based on the auxiliary turn-off signal; and a power supply module for providing a power supply voltage and adjusting the drain-source voltage of the DUT by adjusting the power supply voltage. This invention solves the problems of high cost and limited testing range of existing SOA test equipment.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit design technology, and in particular relates to a test circuit and test method. Background Technology

[0002] Metal-oxide-semiconductor field-effect transistors, also known as MOSFETs, are very common semiconductor devices with wide applications, covering almost all power electronic circuit designs. They are particularly important in applications such as switching power supplies, inverters, BLDC (brushless DC motors), and BMS (battery management systems). However, they often suffer from problems such as burnout and severe explosions. This is because switching devices are in a state of high voltage and high current for a long time. Once overvoltage or overcurrent occurs, the wafer junction temperature rises rapidly. If heat dissipation is not timely, it will lead to device damage, or even explosion, which is very dangerous.

[0003] The ability of switching devices to operate safely and continuously is a primary concern for designers. Understanding and correctly using the SOA (Safe Operating Area) of switching devices can significantly improve their stability and extend their lifespan. While MOSFET datasheets include SOA curves, these are derived from software simulations and represent theoretical values, not actual values. In reality, actual values ​​are influenced by manufacturing processes and packaging, and may differ from theoretical values. Furthermore, SOA curves in datasheets typically only show the limiting voltage and current values ​​at different time points: 1μs, 10μs, 100μs, 1ms, and 10ms. Figure 1 As shown, the limiting voltage and current values ​​at other times such as 50μs and 100ms cannot be directly found from the figure and need to be estimated by the designer, which increases the risk of device damage in the design application.

[0004] In practical applications, due to the wide variety of MOSFETs and the fact that SOA testing involves failure testing with high voltage and high current, there is currently no unified and efficient testing equipment; all testing equipment is self-developed. Moreover, some existing integrated testing equipment on the market is expensive and has limited testing voltage and current ranges. Therefore, providing a low-cost testing device with a wider testing range is a pressing technical problem that those skilled in the art urgently want to solve.

[0005] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a test circuit and test method to solve the problems of high price and limited test range of existing SOA test equipment.

[0007] To achieve the above and other related objectives, the present invention provides a test circuit suitable for SOA testing of power semiconductor devices, the test circuit comprising:

[0008] A module under test (DUT) is used to provide a device under test (DUT) for testing the limits of drain-source voltage and on-current when the DUT is turned on.

[0009] A pulse drive module, connected to the module under test, is used to control the switching of the device under test based on the pulse signal and the comparison result.

[0010] A current detection module, connected to the module under test, is used to detect the on-current of the device under test and obtain the detection voltage;

[0011] A constant current control module is connected between the current detection module and the pulse drive module. It is used to compare the detected voltage and the reference voltage, and to perform constant current control on the conduction current according to the comparison result. The value of the conduction current is adjusted by adjusting the value of the reference voltage.

[0012] An overcurrent drive module, connected to the current detection module, is used to generate a synchronous turn-on signal based on the pulse signal, and to compare the detected voltage with a threshold voltage, and generate an auxiliary turn-off signal when the detected voltage is greater than the threshold voltage.

[0013] An auxiliary switch module is connected between the overcurrent drive module and the device under test (DUT). It is used to perform an on operation according to the synchronous on signal to achieve synchronous on-time with the DUT, and to perform an off operation according to the auxiliary off signal to cut off the current path of the DUT.

[0014] A power supply module, connected to the auxiliary switch module, is used to provide a power supply voltage and adjust the drain-source voltage of the device under test by adjusting the value of the power supply voltage.

[0015] Optionally, the module under test includes a device under test (DUT) and a first resistor. The control terminal of the DUT is connected to the output terminal of the pulse drive module. The first terminal of the DUT is connected to a floating ground and leads out a first voltage measurement point and a current measurement point. The second terminal of the DUT is connected to the detection terminal of the current detection module and leads out a second voltage measurement point. The first resistor is connected between the control terminal and the second terminal of the DUT. The drain-source voltage of the DUT is tested through the first voltage measurement point and the second voltage measurement point, and the on-state current of the DUT is tested through the current measurement point.

[0016] Optionally, the pulse drive module includes an upper switch, a lower switch, and a second resistor. The control terminals of the upper and lower switches are connected to each other and to the output terminal of the pulse signal and the constant current control module. The first terminal of the upper switch is connected to the driving voltage, and the second terminal of the upper switch is connected to the first terminal of the lower switch and the first terminal of the second resistor. The second terminal of the lower switch is connected to control ground, and the second terminal of the second resistor serves as the output terminal of the pulse drive module. Alternatively, the pulse drive module further includes a third resistor and a diode. The first terminal of the third resistor is connected to the second terminal of the upper switch, the second terminal of the third resistor is connected to the anode of the diode, and the cathode of the diode is connected to the second terminal of the second resistor.

[0017] Optionally, the current detection module includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and a first operational amplifier. The first end of the fourth resistor is connected to the first end of the fifth resistor and serves as the detection terminal of the current detection module. The second end of the fourth resistor is connected to the first end of the sixth resistor and connected to power ground. The second end of the fifth resistor is connected to the first input terminal of the first operational amplifier and connected to control ground via the seventh resistor. The second end of the sixth resistor is connected to the second input terminal of the first operational amplifier and connected to the output terminal of the first operational amplifier via the eighth resistor. The output terminal of the first operational amplifier is connected to the first end of the ninth resistor. The second end of the ninth resistor serves as the output terminal of the current detection module. The number of fourth resistors is greater than or equal to one; when the number is greater than one, the fourth resistors are connected in parallel. Alternatively, the current detection module further includes a first capacitor connected in parallel across the four fourth resistors.

[0018] Optionally, the constant current control module includes a voltage comparison unit and a reference providing unit;

[0019] The voltage comparison unit includes a first comparator and a tenth resistor. The first input terminal of the first comparator is connected to the output terminal of the reference providing unit, the second input terminal of the first comparator is connected to the output terminal of the current detection module, the output terminal of the first comparator is connected to the first terminal of the tenth resistor, and the second terminal of the tenth resistor serves as the output terminal of the constant current control module. Alternatively, the voltage comparison unit further includes at least one of a first filter and a second filter, wherein: the first filter includes an eleventh resistor and a second capacitor, the second capacitor is connected in parallel across the eleventh resistor, the first terminal of the eleventh resistor is connected to the first input terminal of the first comparator, and the second terminal of the eleventh resistor is connected to control ground; the second filter includes a twelfth resistor, a third capacitor, and a fourth capacitor, the third capacitor is connected in parallel across the twelfth resistor, the first terminal of the twelfth resistor is connected to the output terminal of the current detection module and connected to control ground via the fourth capacitor, and the second terminal of the twelfth resistor is connected to the second input terminal of the first comparator.

[0020] The reference providing unit includes a first adjustable potentiometer, a thirteenth resistor, and a fourteenth resistor. The first terminal of the first adjustable potentiometer is connected to the operating voltage, and the second terminal of the first adjustable potentiometer is connected to the control ground. The sliding terminal of the first adjustable potentiometer is connected to the first terminal of the fourteenth resistor via the thirteenth resistor, and the second terminal of the fourteenth resistor serves as the output terminal of the reference providing unit. Alternatively, the reference providing unit may further include a fifth capacitor and a sixth capacitor, which are respectively connected between the two ends of the thirteenth resistor and the control ground.

[0021] Optionally, the overcurrent drive module includes:

[0022] An overcurrent detection unit, connected to the current detection module, is used to compare the detected voltage with the threshold voltage and generate an overcurrent protection signal when the detected voltage is greater than the threshold voltage.

[0023] A threshold providing unit, connected to the overcurrent detection unit, is used to provide the threshold voltage;

[0024] An isolation drive unit, connected to the overcurrent detection unit, is used to generate the synchronous turn-on signal based on the pulse signal and the auxiliary turn-off signal based on the overcurrent protection signal.

[0025] Optionally, the overcurrent detection unit includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a second comparator, and a latch. The first input terminal of the second comparator is connected to the output terminal of the current detection module via the fifteenth resistor. The second input terminal of the second comparator is connected to the output terminal of the threshold providing unit. The output terminal of the second comparator is connected to the clock terminal of the latch via the sixteenth resistor. The data terminal of the latch is connected to the operating voltage via the seventeenth resistor. The inverting output terminal of the latch is connected to the first terminal of the eighteenth resistor. The second terminal of the eighteenth resistor serves as the output terminal of the overcurrent detection unit. Alternatively, the overcurrent detection unit further includes at least one of a seventh capacitor and an eighth capacitor, wherein: the first terminal of the seventh capacitor is connected to the first input terminal of the second comparator, and the second terminal of the seventh capacitor is connected to control ground; the first terminal of the eighth capacitor is connected to the second input terminal of the second comparator, and the second terminal of the eighth capacitor is connected to control ground.

[0026] Optionally, the threshold providing unit includes a second adjustable potentiometer, a nineteenth resistor, a twentieth resistor, and a second operational amplifier. The first terminal of the second adjustable potentiometer is connected to the operating voltage, the second terminal of the second adjustable potentiometer is connected to control ground, the sliding terminal of the second adjustable potentiometer is connected to the first input terminal of the second operational amplifier via the nineteenth resistor, the second input terminal of the second operational amplifier is connected to its output terminal, the output terminal of the second operational amplifier is connected to the first terminal of the twentieth resistor, and the second terminal of the twentieth resistor serves as the output terminal of the threshold providing unit. Alternatively, the threshold providing unit further includes a ninth capacitor and a tenth capacitor, the ninth capacitor and the tenth capacitor being respectively connected between the two ends of the nineteenth resistor and the control ground.

[0027] Optionally, the isolation drive unit includes a 21st resistor, a 22nd resistor, a 23rd resistor, an optocoupler, and a voltage converter. The first end of the 21st resistor is connected to the pulse signal and the output of the overcurrent detection unit. The second end of the 21st resistor is connected to the first end of the light-emitting device in the optocoupler and connected to the control ground via the 22nd resistor. The second end of the light-emitting device in the optocoupler is connected to the control ground. The first end of the light-receiving device in the optocoupler is connected to the first end of the 23rd resistor. The second end of the light-receiving device in the optocoupler is connected to the floating ground. The second end of the 23rd resistor serves as the output of the overcurrent drive module. The voltage converter is used to convert the drive voltage into a floating voltage to power the optocoupler and to convert the control ground into a floating ground.

[0028] Optionally, the auxiliary switch module includes at least one auxiliary switch unit, and when the number of auxiliary switch units is greater than one, the auxiliary switch units are connected in parallel; wherein, the auxiliary switch unit includes an auxiliary switch transistor, a twenty-fourth resistor and a twenty-fifth resistor, the control terminal of the auxiliary switch transistor is connected to the output terminal of the overcurrent drive module via the twenty-fourth resistor, the first terminal of the auxiliary switch transistor is connected to the power supply voltage, and the second terminal of the auxiliary switch transistor is connected to the floating ground and connected to its control terminal via the twenty-fifth resistor.

[0029] Optionally, the power supply module includes an adjustable power supply and an eleventh capacitor. The positive terminal of the adjustable power supply generates the power supply voltage, and the negative terminal of the adjustable power supply is connected to power ground. The eleventh capacitor is connected in parallel across the two ends of the adjustable power supply. Alternatively, the power supply module further includes a twenty-sixth resistor and a first light-emitting diode (LED). The first end of the twenty-sixth resistor is connected to the positive terminal of the adjustable power supply, the second end of the twenty-sixth resistor is connected to the anode terminal of the first LED, and the cathode terminal of the first LED is connected to power ground.

[0030] Optionally, the test circuit further includes a voltage supply module for providing a drive voltage and an operating voltage; wherein the voltage supply module includes an adjustable DC source, a linear regulator, a third adjustable potentiometer, a twenty-seventh resistor, a twelfth capacitor, and a thirteenth capacitor; the positive terminal of the adjustable DC source is connected to the first terminal of the twelfth capacitor and the input terminal of the linear regulator, serving as the drive voltage output terminal of the voltage supply module; the negative terminal of the adjustable DC source is connected to control ground; the output terminal of the linear regulator is connected to the first terminal of the third adjustable potentiometer and the first terminal of the twenty-seventh resistor, serving as the operating voltage output terminal of the voltage supply module; the second terminal of the third adjustable potentiometer is connected to control ground; the sliding terminal of the third adjustable potentiometer is connected to the second terminal of the twenty-seventh resistor and the common terminal of the linear regulator; the second terminal of the twenty-seventh resistor is also connected to control ground via the thirteenth capacitor; or, the voltage supply module further includes at least one of an input filter, an output filter, and an operating indicator. The input filter includes a first inductor, a second inductor, a fourteenth capacitor, and a fifteenth capacitor. The first end of the first inductor is connected to the positive terminal of the adjustable DC source. The second end of the first inductor is connected to the first end of the twelfth capacitor and the input terminal of the linear regulator. The first end of the second inductor is connected to the negative terminal of the adjustable DC source. The second end of the second inductor is connected to control ground. The fourteenth capacitor is connected between the first end of the first inductor and the first end of the second inductor. The fifteenth capacitor is connected between the second end of the first inductor and the second end of the second inductor. The output filter includes at least one sixteenth capacitor, which is connected in parallel between the first and second ends of the third adjustable potentiometer. The operating indicator includes a twenty-eighth resistor and a second LED. The first end of the twenty-eighth resistor is connected to the output terminal of the linear regulator. The second end of the twenty-eighth resistor is connected to the anode terminal of the second LED. The cathode terminal of the second LED is connected to control ground.

[0031] The present invention also provides a test method based on the test circuit described in any one of the above claims, the test method comprising:

[0032] The module under test and the auxiliary switch module are synchronously turned on by a pulse signal, wherein the pulse duration of the pulse signal is a preset time;

[0033] The on-current of the device under test in the module under test is detected and the detection voltage is obtained. The detection voltage is compared with the reference voltage and the on-current is controlled by constant current based on the comparison result.

[0034] The drain-source voltage of the device under test is adjusted by adjusting the power supply voltage, and the on-current of the device under test is adjusted by adjusting the reference voltage, thereby achieving the limit value test of the drain-source voltage and on-current of the device under test under a preset time.

[0035] The detection voltage and the threshold voltage are compared, and when the detection voltage is greater than the threshold voltage, the auxiliary switch module is controlled to turn off to cut off the current path of the device under test.

[0036] As described above, the test circuit and test method of the present invention allow for flexible adjustment of circuit parameters according to test requirements. They are applicable to SOA testing of power semiconductor devices with different packages and specifications, have a wide testing range, and can improve the diversity and accuracy of SOA testing, thus helping to obtain more realistic SOA curves. The circuit is mainly composed of conventional electronic components such as resistors, capacitors, diodes, transistors, and operational amplifiers, and is inexpensive. Attached Figure Description

[0037] Figure 1 The image shows a schematic diagram of the SOA curve given in the datasheet of a power semiconductor device.

[0038] Figure 2 The diagram shown is a schematic representation of the test circuit of this invention.

[0039] Figure 3 The diagram shown is a specific circuit implementation schematic of the test circuit of this invention.

[0040] Figure 4 The diagram shown is a schematic of another specific circuit implementation of the test circuit of the present invention.

[0041] Component designation explanation

[0042] 100 Test Circuit

[0043] 110 Module under test

[0044] 120 Pulse Drive Module

[0045] 130 Current Detection Module

[0046] 140 Constant Current Control Module

[0047] 141 Voltage Comparison Unit

[0048] 141a First Filter

[0049] 141b Second Filter

[0050] 142 Reference Providing Unit

[0051] 150 Overcurrent Drive Unit

[0052] 151 Overcurrent Detection Unit

[0053] 152 Threshold Providing Units

[0054] 153 Isolated Drive Unit

[0055] 153a Optocoupler Isolator

[0056] 153b Voltage Converter

[0057] 160 Auxiliary Switch Module

[0058] 161 Auxiliary Switching Unit

[0059] 170 power supply module

[0060] 180Voltage Supply Module

[0061] 181 Adjustable DC Power Supply

[0062] 182 Linear Regulator

[0063] 183 Input Filter

[0064] 184 Output Filter

[0065] 185 Working Indicator Detailed Implementation

[0066] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0067] Please see Figures 2 to 4 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0068] like Figures 2 to 4As shown, this embodiment provides a test circuit 100 suitable for SOA (Safe Operating Area) testing of power semiconductor devices; wherein, the test circuit 100 includes a module under test 110, a pulse drive module 120, a current detection module 130, a constant current control module 140, an overcurrent drive module 150, an auxiliary switch module 160, and a power supply module 170, and further, the test circuit 100 also includes a voltage supply module 180.

[0069] like Figures 2 to 4 As shown, the module under test 100 is used to provide the device under test (DUT) to measure the drain-source voltage V when the DUT is turned on. DS and conduction current I D The limit value test is performed to obtain the SOA curve of the device under test (DUT).

[0070] In one implementation, such as Figure 3 and Figure 4 As shown, the module under test 100 includes a device under test (DUT) and a first resistor R1. The control terminal of the DUT is connected to the output terminal of the pulse drive module 120. The first terminal of the DUT is connected to the floating ground FGND and leads out a first voltage measurement point DUT_U1 and a current measurement point DUT_I. The second terminal of the DUT is connected to the detection terminal of the current detection module 130 and leads out a second voltage measurement point DUT_U2. The first resistor R1 is connected between the control terminal and the second terminal of the DUT. As an optional solution, the DUT can be a power MOS device, such as a power NMOS device. In this case, the control terminal refers to the gate terminal, the first terminal refers to the drain terminal, and the second terminal refers to the source terminal. Of course, it is also feasible for the DUT to be other types of power semiconductor devices, and this is not a limitation. In this embodiment, the drain-source voltage V of the DUT is measured through the first voltage measurement point DUT_U1 and the second voltage measurement point DUT_U2. DS To facilitate the measurement of drain-source voltage V DS Limit value testing involves measuring the on-state current I of the device under test (DUT) through the current measurement point DUT_I. D To facilitate the conduction current I D Limit value testing; of course, a third voltage measurement point DUT_U3 can also be led out from the control terminal of the device under test (DUT), and the gate voltage V of the DUT can be tested through the third voltage measurement point DUT_U3. G This is to meet specific application requirements. In practical applications, voltage and current probes are connected to an oscilloscope to measure the voltage and current points, respectively, and the drain-source voltage V of the device under test (DUT) is read using the oscilloscope. DS and conduction current I D This facilitates the completion of limit value tests and the plotting of SOA curves for the device under test (DUT).

[0071] like Figures 2 to 4 As shown, the pulse drive module 120 is connected to the module under test 110 and is used to control the switching of the device under test (DUT) according to the pulse signal and the comparison result.

[0072] In one implementation, such as Figure 3 As shown, the pulse drive module 120 includes an upper switch Q1, a lower switch Q2, and a second resistor R2. The control terminals of the upper switch Q1 and the lower switch Q2 are connected to each other and connected to a pulse signal. They are also connected to the output terminal of the constant current control module 140 to receive the comparison result. The first terminal of the upper switch Q1 is connected to the drive voltage VGS. The second terminal of the upper switch Q1 is connected to the first terminal of the lower switch Q2 and the first terminal of the second resistor R2. The second terminal of the lower switch Q2 is connected to the control ground SGND. The second terminal of the second resistor R2 serves as the output terminal of the pulse drive module 120. In this embodiment, the upper switch Q1 and the lower switch Q2 form a totem pole structure. When the control terminal of the totem pole is connected to a high level, the upper switch Q1 is turned on and the lower switch Q2 is turned off. The driving voltage VGS is output to the control terminal of the device under test (DUT) via the second resistor R2 to drive the DUT to turn on. When the control terminal of the totem pole structure is connected to a low level, the upper switch Q1 is turned off and the lower switch Q2 is turned on. The control terminal of the DUT is connected to the control ground via the second resistor R2 and is turned off. In specific application scenarios, when a pulse signal arrives (i.e., when the pulse signal is high-level), if the constant current control module 140 has no output or outputs a high level (i.e., the comparison result is high-level), the control terminal of the totem-pole structure is connected to a high level. If the constant current control module 140 outputs a low level (i.e., the comparison result is low-level), the control terminal of the totem-pole structure is connected to a low level. In practical applications, the pulse signal is usually provided by a pulse generator PG. The pulse duration of the pulse signal can be set by the pulse generator PG, meaning that the pulse duration of the pulse signal is adjustable. This allows the drain-source voltage V of the device under test (DUT) to be measured at different preset times. DS and conduction current I D Limit value test.

[0073] In another implementation, such as Figure 4As shown, the pulse drive module 120 also includes a third resistor R3 and a diode D0. The first end of the third resistor R3 is connected to the second end of the upper switch Q1, the second end of the third resistor R3 is connected to the anode of the diode D0, and the cathode of the diode D0 is connected to the second end of the second resistor R2. In this embodiment, the second resistor R2 is used as a turn-off resistor, and the third resistor R3 is used as a turn-on resistor. When the control terminal of the totem-pole structure is connected to a high level, causing the upper switch Q1 to turn on and the lower switch Q2 to turn off, the drive voltage VGS is output to the control terminal of the device under test (DUT) via the turn-on resistor (i.e., the third resistor R3) to drive the DUT to turn on. When the control terminal of the totem-pole structure is connected to a low level, causing the upper switch Q1 to turn off and the lower switch Q2 to turn on, the control terminal of the DUT is turned off via the turn-off resistor (i.e., the second resistor R2) connected to control ground. Through the independent design of the turn-on and turn-off resistors, the turn-on and turn-off times of the DUT can be adjusted separately to meet different application requirements.

[0074] like Figures 2 to 4 As shown, the current detection module 130 is connected to the module under test 110 and is used to detect the on-state current I of the device under test (DUT). D And obtain the detection voltage VID.

[0075] In one implementation, such as Figure 3 As shown, the current detection module 130 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a first operational amplifier OP1. The first end of the fourth resistor R4 is connected to the first end of the fifth resistor R5 and serves as the detection terminal of the current detection module 130, connecting to the second terminal of the device under test (DUT). The second end of the fourth resistor R4 is connected to the first end of the sixth resistor R6 and connected to power ground PGND. The second end of the fifth resistor R5 is connected to the first input terminal (e.g., non-inverting input) of the first operational amplifier OP1 and connected to control ground SGND via the seventh resistor R7. The second end of the sixth resistor R6 is connected to the second input terminal (e.g., inverting input) of the first operational amplifier OP1 and connected to the output terminal of the first operational amplifier OP1 via the eighth resistor R8. The output terminal of the first operational amplifier OP1 is connected to the first end of the ninth resistor R9, and the second end of the ninth resistor R9 serves as the output terminal of the current detection module 130, outputting a detection voltage VID. Additionally, the power supply terminal of the first operational amplifier OP1 is connected to the operating voltage VCC, and the ground terminal of the first operational amplifier OP1 is connected to control ground SGND (not shown in the figure). As an optional solution, the fourth resistor R4 can be one or more, and its resistance value and number are determined by the conduction current I to be detected. DThe size is determined by the number of fourth resistors R4; when the number of fourth resistors is greater than one, for example, if there are four fourth resistors, the four fourth resistors R4 are connected in parallel. Furthermore, as... Figure 4 As shown, the current detection module 130 also includes a first capacitor C1 for filtering; wherein, the first capacitor C1 is connected in parallel across the fourth resistor R4. In this embodiment, the fifth resistor R5 and the sixth resistor R6 are connected across the fourth resistor R4 to achieve the conduction current I. D The detection is performed, and the detected on-current I is amplified by the first operational amplifier OP1. D The amplified output is used to obtain the detection voltage VID. In practical applications, in order to improve the response speed, the first operational amplifier OP1 can be implemented using a high-speed operational amplifier.

[0076] like Figures 2 to 4 As shown, the constant current control module 140 is connected between the current detection module 130 and the pulse drive module 120. It is used to compare the detected voltage VID with the reference voltage VREF1, and adjust the conduction current I based on the comparison result. D Constant current control is performed, wherein the on-current I is adjusted by adjusting the value of the reference voltage VREF1. D The value is used to test the on-current I of the device under test (DUT). D The limit value.

[0077] As an example, such as Figure 3 and Figure 4 As shown, the constant current control module 140 includes a voltage comparison unit 141 and a reference providing unit 142; wherein, the voltage comparison unit 141 is connected between the current detection module 130 and the pulse drive module 120, and is used to compare the detected voltage VID and the reference voltage VREF1 and generate a comparison result; the reference providing unit 142 is connected to the voltage comparison unit 141 and is used to provide the reference voltage VREF1.

[0078] In one implementation, such as Figure 3 As shown, the voltage comparison unit 141 includes a first comparator CMP1 and a tenth resistor R10; wherein, the first input terminal (e.g., non-inverting input terminal) of the first comparator CMP1 is connected to the output terminal of the reference providing unit 142 to receive the reference voltage VREF1, the second input terminal (e.g., inverting input terminal) of the first comparator CMP1 is connected to the output terminal of the current detection module 130 to receive the detected voltage VID, the output terminal of the first comparator CMP1 is connected to the first terminal of the tenth resistor R10, and the second terminal of the tenth resistor R10 serves as the output terminal of the constant current control module 140 to output the comparison result; in addition, the power supply terminal of the first comparator CMP1 is connected to the operating voltage VCC, and the ground terminal of the first comparator CMP1 is connected to the control ground SGND. Further, as... Figure 4As shown, the voltage comparison unit 141 further includes at least one of a first filter 141a and a second filter 141b. Optionally, the voltage comparison unit 141 includes both a first filter 141a and a second filter 141b. The first filter 141a is connected to the first input terminal of the first comparator CMP1 and is used to filter the reference voltage VREF1. The second filter 141b is connected to the second input terminal of the first comparator CMP1 and is used to filter the detected voltage VID. Specifically, the first filter 141a includes an eleventh resistor R11 and a second capacitor C2. The second capacitor C2 is connected in parallel across the eleventh resistor R11. The first terminal of the eleventh resistor R11 is connected to the first input terminal of the first comparator CMP1, and the second terminal of the eleventh resistor R11 is connected to the control ground SGND. The second filter 141b includes a twelfth resistor R12, a third capacitor C3, and a fourth capacitor C4. The third capacitor C3 is connected in parallel across the twelfth resistor R12. The first end of the twelfth resistor R12 is connected to the output of the current detection module 130 and then connected to control ground SGND via the fourth capacitor C4. The second end of the twelfth resistor R12 is connected to the second input of the first comparator CMP1. In this embodiment, when the detected voltage VID is less than the reference voltage VREF1, the first comparator CMP1 outputs a high level. At this time, because the pulse signal is also high, the pulse drive module 120 keeps the device under test (DUT) on, and the conduction current I of the DUT... D As the voltage increases, the detection voltage VID also increases. When the detection voltage VID is greater than the reference voltage VREF1, the first comparator CMP1 outputs a low level. At this time, the device under test (DUT) is turned off through the pulse drive module 120, and the conduction current I of the DUT... D As the voltage decreases, the detection voltage VID also decreases; this process is repeated to control the on-state current I of the device under test (DUT). D Maintaining the set value corresponding to the reference voltage VREF1, achieving the conduction current I D Constant current control.

[0079] In one implementation, such as Figure 3 As shown, the reference providing unit 142 includes a first adjustable potentiometer PR1, a thirteenth resistor R13, and a fourteenth resistor R14; wherein, the first terminal of the first adjustable potentiometer PR1 is connected to the operating voltage VCC, the second terminal of the first adjustable potentiometer PR1 is connected to the control ground SGND, the sliding terminal of the first adjustable potentiometer PR1 is connected to the first terminal of the fourteenth resistor R14 via the thirteenth resistor R13, and the second terminal of the fourteenth resistor R14 serves as the output terminal of the reference providing unit 142 to output the reference voltage VREF1. Further, as... Figure 4As shown, the reference providing unit 142 also includes a fifth capacitor C5 and a sixth capacitor C6 for filtering. The fifth capacitor C5 and the sixth capacitor C6 are respectively connected between the two ends of the thirteenth resistor R13 and the control ground SGND. For example, the fifth capacitor C5 is connected between the first end of the thirteenth resistor R13 and the control ground SGND, and the sixth capacitor C6 is connected between the second end of the thirteenth resistor R13 and the control ground SGND. In this embodiment, the magnitude of the reference voltage VREF1 is set by the first adjustable potentiometer PR1. Thus, the on-current I of the device under test (DUT) can be adjusted by adjusting the value of the reference voltage VREF1. D The value is used to test the on-current I of the device under test (DUT). D The limit value.

[0080] like Figures 2 to 4 As shown, the overcurrent drive module 150 is connected to the current detection module 130. It is used to generate a synchronous turn-on signal based on the pulse signal, and to compare the detection voltage VID with the threshold voltage VREF2. When the detection voltage VID is greater than the threshold voltage VREF2, an auxiliary turn-off signal is generated to facilitate overcurrent protection.

[0081] As an example, such as Figure 3 and Figure 4 As shown, the overcurrent drive module 150 includes an overcurrent detection unit 151, a threshold providing unit 152, and an isolation drive unit 153.

[0082] The overcurrent detection unit 151 is connected to the current detection module 130 and is used to compare the detection voltage VID and the threshold voltage VREF2, and generate an overcurrent protection signal OFF_CTL when the detection voltage VID is greater than the threshold voltage VREF2.

[0083] In one implementation, such as Figure 3As shown, the overcurrent detection unit 151 includes a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a second comparator CMP2, and a latch LAT. The first input terminal (e.g., the non-inverting input terminal) of the second comparator CMP2 is connected to the output terminal of the current detection module 130 via the fifteenth resistor R15 to receive the detection voltage VID. The second input terminal (e.g., the inverting input terminal) of the second comparator CMP2 is connected to the output terminal of the threshold providing unit 152 to receive the threshold voltage VREF2. The input of the second comparator CMP2... The output terminal is connected to the clock terminal of the latch LAT via the sixteenth resistor R16. The data terminal of the latch LAT is connected to the operating voltage VCC via the seventeenth resistor R17. The inverting output terminal of the latch LAT is connected to the first terminal of the eighteenth resistor R18. The second terminal of the eighteenth resistor R18 serves as the output terminal of the overcurrent detection unit 151 to output the overcurrent protection signal OFF_CTL. Additionally, the power supply terminal of the second comparator CMP2 is connected to the operating voltage VCC, the ground terminal of the second comparator CMP2 is connected to the control ground SGND, and the power supply terminal of the latch LAT is also connected to the operating voltage VCC. Further, as... Figure 4 As shown, the overcurrent detection unit 151 further includes at least one of a seventh capacitor C7 and an eighth capacitor C8. Optionally, the overcurrent detection unit 151 includes both a seventh capacitor C7 and an eighth capacitor C8. The first terminal of the seventh capacitor C7 is connected to the first input terminal of the second comparator CMP2, and the second terminal of the seventh capacitor C7 is connected to the control ground SGND, used for filtering the detected voltage VID. The first terminal of the eighth capacitor C8 is connected to the second input terminal of the second comparator CMP2, and the second terminal of the eighth capacitor C8 is connected to the control ground SGND, used for filtering the threshold voltage VREF2. In this embodiment, when the detected voltage VID is less than the threshold voltage VREF2, the second comparator CMP2 outputs a low level, and the latch LAT has no output. At this time, it is considered that no overcurrent protection signal OFF_CTL is generated. When the detected voltage VID is greater than the threshold voltage VREF2, the second comparator CMP2 outputs a high level, and the latch LAT has an output. At this time, the latch LAT generates a low-level overcurrent protection signal OFF_CTL.

[0084] The threshold providing unit 152 is connected to the overcurrent detection unit 151 and is used to provide a threshold voltage VREF2; wherein, the overcurrent protection point can be adjusted by adjusting the value of the threshold voltage VREF2.

[0085] In one implementation, such as Figure 3As shown, the threshold providing unit 152 includes a second adjustable potentiometer PR2, a nineteenth resistor R19, a twentieth resistor R20, and a second operational amplifier OP2. The first terminal of the second adjustable potentiometer PR2 is connected to the operating voltage VCC, and the second terminal is connected to control ground SGND. The sliding terminal of the second adjustable potentiometer PR2 is connected to the first input terminal (e.g., non-inverting input) of the second operational amplifier OP2 via the nineteenth resistor R19. The second input terminal (e.g., inverting input) of the second operational amplifier OP2 is connected to its output terminal. The output terminal of the second operational amplifier OP2 is connected to the first terminal of the twentieth resistor R20, and the second terminal of the twentieth resistor R20 serves as the output terminal of the threshold providing unit 152 to output a threshold voltage VREF2. Furthermore, the power supply terminal of the second operational amplifier OP2 is connected to the operating voltage VCC, and the ground terminal of the second operational amplifier OP2 is connected to control ground SGND (not shown in the figure). Further, as... Figure 4 As shown, the threshold providing unit 152 also includes a ninth capacitor C9 and a tenth capacitor C10 for filtering. The ninth capacitor C9 and the tenth capacitor C10 are respectively connected between the two ends of the nineteenth resistor R19 and the control ground SGND. For example, the ninth capacitor C9 is connected between the first end of the nineteenth resistor R19 and the control ground SGND, and the tenth capacitor C10 is connected between the second end of the nineteenth resistor R19 and the control ground SGND. In this embodiment, the value of the threshold voltage VREF2 is determined by the second adjustable potentiometer PR2. Thus, the value of the overcurrent protection point can be adjusted by adjusting the value of the threshold voltage VREF2 to meet different application requirements. In practical applications, to improve the response speed, the second operational amplifier OP2 can be implemented using a high-speed operational amplifier.

[0086] The isolation drive unit 153 is connected to the overcurrent detection unit 151 and is used to generate a synchronous turn-on signal based on the pulse signal and an auxiliary turn-off signal based on the overcurrent protection signal OFF_CTL. In addition, the isolation drive unit 153 is also used to provide electrical isolation to the auxiliary switch module 160.

[0087] In one implementation, such as Figure 3 and Figure 4As shown, the isolation drive unit 153 includes a 21st resistor R21, a 22nd resistor R22, a 23rd resistor R23, an optocoupler 153a, and a voltage converter 153b. The first terminal of the 21st resistor R21 is connected to a pulse signal and also to the output terminal of the overcurrent detection unit 151 to receive the overcurrent protection signal OFF_CTL. The second terminal of the 21st resistor R21 is connected to the first terminal of the light-emitting device in the optocoupler 153a and connected to the control ground SGND via the 22nd resistor R22. The optocoupler 153a... The second end of the light-emitting device in 53a is connected to the control ground SGND. The first end of the light-receiving device in the optocoupler 153a is connected to the first end of the twenty-third resistor R23. The second end of the light-receiving device in the optocoupler 153a is connected to the floating ground FGND. The second end of the twenty-third resistor R23 serves as the output terminal of the overcurrent drive module 150 to output an auxiliary shutdown signal. The voltage converter 153b is used to convert the drive voltage VGS into a floating voltage VFZ to power the optocoupler 153a and convert the control ground SGND into the floating ground FGND. In this embodiment, when the overcurrent detection unit 151 has no output, the optocoupler 153a generates a high-level synchronous turn-on signal based on the pulse signal to drive the auxiliary switch module 160 to turn on, thereby realizing the synchronous turn-on of the auxiliary switch module 160 and the device under test 110; when the overcurrent detection unit 151 outputs a low-level overcurrent protection signal OFF_CTL, the optocoupler 153a outputs a low-level auxiliary turn-off signal based on the low-level overcurrent protection signal OFF_CTL to turn off the auxiliary switch module 160, thereby cutting off the current path of the device under test DUT and playing the role of overcurrent protection.

[0088] like Figures 2 to 4 As shown, the auxiliary switch module 160 is connected between the overcurrent drive module 150 and the device under test (DUT) 110. It is used to perform an on operation according to the synchronous on signal to realize the synchronous on-time of the auxiliary switch module 160 and the DUT, thereby forming a current path. It also performs an off operation according to the auxiliary off signal to cut off the current path of the DUT, thus playing the role of overcurrent protection.

[0089] In one implementation, such as Figure 3 and Figure 4As shown, the auxiliary switch module 160 includes at least one auxiliary switch unit 161, wherein when the number of auxiliary switch units 161 is greater than one, the auxiliary switch units 161 are connected in parallel. Specifically, the auxiliary switch unit 161 includes an auxiliary switch transistor Q3, a twenty-fourth resistor R24, and a twenty-fifth resistor R25; wherein the control terminal of the auxiliary switch transistor Q3 is connected to the output terminal of the overcurrent drive module 150 via the twenty-fourth resistor R24, the first terminal of the auxiliary switch transistor Q3 is connected to the power supply voltage VDD, and the second terminal of the auxiliary switch transistor Q3 is connected to the floating ground FGND and connected to its control terminal via the twenty-fifth resistor R25. In this embodiment, the auxiliary switch transistor Q3 and the device under test (DUT) are connected in series via the floating ground FGND, wherein the DUT and the auxiliary switch transistor Q3 are synchronously turned on by a pulse signal to form a current path; when the DUT fails, the current in the path increases sharply, the overcurrent drive module 150 outputs an auxiliary turn-off signal, and the auxiliary switch transistor Q3 is turned off to cut off the current path of the DUT, thereby playing an overcurrent protection role. It should be noted that the number of auxiliary switch units 161 can be designed according to the device under test (DUT), and there is no limitation on this.

[0090] like Figures 2 to 4 As shown, the power supply module 170 is connected to the auxiliary switch module 160 to provide the power supply voltage VDD, and adjusts the drain-source voltage V of the device under test (DUT) by adjusting the value of the power supply voltage VDD. DS The value is used to test the drain-source voltage V of the device under test (DUT). DS The limit value.

[0091] In one implementation, such as Figure 3 As shown, the power supply module 170 includes an adjustable power supply DC1 and an eleventh capacitor C11; wherein, the positive terminal of the adjustable power supply DC1 generates the power supply voltage VDD, the negative terminal of the adjustable power supply DC1 is connected to power ground PGND, and the eleventh capacitor C11 is connected in parallel across the adjustable power supply DC1. Further, as... Figure 4 As shown, the power supply module 170 also includes a 26th resistor R26 and a first LED D1; wherein, the first end of the 26th resistor R26 is connected to the positive terminal of the adjustable power supply DC1, the second end of the 26th resistor R26 is connected to the anode terminal of the first LED D1, and the cathode terminal of the first LED D1 is connected to power ground PGND. In this embodiment, when powered by the adjustable power supply DC1, the drain-source voltage V of the device under test (DUT) can be adjusted by adjusting the value of the power supply voltage VDD. DS In order to achieve drain-source voltage V DS The limit value test; in addition, the first LED D1 is used as a power indicator.

[0092] like Figures 2 to 4As shown, the voltage supply module 180 is used to provide the drive voltage VGS and the operating voltage VCC. For example, it provides the drive voltage VGS to the isolation drive unit 153 in the pulse drive module 120 and the overcurrent drive module 150, and provides the operating voltage VCC to the voltage comparison unit 141 and the reference supply unit 142 in the constant current control module 140, and the overcurrent detection unit 151 and the threshold supply unit 152 in the overcurrent drive module 150.

[0093] In one implementation, such as Figure 3 As shown, the voltage supply module 180 includes an adjustable DC source 181, a linear regulator 182, a third adjustable potentiometer PR3, a twenty-seventh resistor R27, a twelfth capacitor C12, and a thirteenth capacitor C13. The positive terminal of the adjustable DC source 181 is connected to the first terminal of the twelfth capacitor C12 and the input terminal of the linear regulator 182, serving as the drive voltage output terminal of the voltage supply module 180 to output the drive voltage VGS. The negative terminal of the adjustable DC source 181 is connected to control ground SGND. The output terminal of the linear regulator 182 is connected to the first terminal of the third adjustable potentiometer PR3 and the first terminal of the twenty-seventh resistor R27, serving as the operating voltage output terminal of the voltage supply module 180 to output the operating voltage VCC. The second terminal of the third adjustable potentiometer PR3 is connected to control ground SGND. The sliding terminal of the third adjustable potentiometer PR3 is connected to the second terminal of the twenty-seventh resistor R27 and the common terminal of the linear regulator 182. The second terminal of the twenty-seventh resistor R27 is also connected to control ground SGND via the thirteenth capacitor C13. Further, as... Figure 4As shown, the voltage supply module 180 further includes at least one of an input filter 183, an output filter 184, and a working indicator 185. Optionally, the voltage supply module 180 simultaneously includes an input filter 183, an output filter 184, and a working indicator 185. Specifically, the input filter 185 includes a first inductor L1, a second inductor L2, a fourteenth capacitor C14, and a fifteenth capacitor C15. The first terminal of the first inductor L1 is connected to the positive terminal of the adjustable DC source 181; the second terminal of the first inductor L2 is connected to the first terminal of the twelfth capacitor C12 and the input terminal of the linear regulator 182; the first terminal of the second inductor L2 is connected to the negative terminal of the adjustable DC source 181; the second terminal of the second inductor L2 is connected to control ground SGND; the fourteenth capacitor C14 is connected between the first terminal of the first inductor L1 and the first terminal of the second inductor L2; and the fifteenth capacitor C15 is connected between the second terminal of the first inductor L1 and the second terminal of the second inductor L2. The output filter 184 includes at least one sixteenth capacitor C16, for example, three sixteenth capacitors C16; wherein the sixteenth capacitor C16 is connected in parallel between the first and second terminals of the third adjustable potentiometer PR3. The operating indicator 185 includes a twenty-eighth resistor R28 and a second LED D2; wherein the first terminal of the twenty-eighth resistor R28 is connected to the output terminal of the linear regulator 182, the second terminal of the twenty-eighth resistor R28 is connected to the anode terminal of the second LED D2, and the cathode terminal of the second LED D2 is connected to control ground SGND. In this embodiment, the driving voltage VGS is mainly used to drive the device under test (DUT). The value of the driving voltage VGS is adjusted by adjusting the value of the adjustable DC source 181, thus enabling testing of DUTs of different specifications. The operating voltage VCC is mainly used to power comparators, operational amplifiers, latches, etc. The value of the operating voltage VCC can be adjusted by the third adjustable potentiometer PR3 to increase the selectivity of the powered components. Additionally, the second LED D2 is used as an operating indicator light.

[0094] Accordingly, this embodiment also provides a test method based on the test circuit 100 above, for testing the SOA curve of power semiconductor devices; wherein the test method includes the following steps.

[0095] Step S1 involves controlling the synchronous activation of the module under test 110 and the auxiliary switch module 160 via a pulse signal, wherein the pulse duration of the pulse signal is a preset time. Specifically, the pulse signal is provided to the pulse drive module 120 and the isolation drive unit 153 to synchronously activate the module under test 110 and the auxiliary switch module 160, thereby forming a current path.

[0096] Step S2: Detect the on-state current I of the device under test (DUT) in the module under test 110. DThe detected voltage VID is obtained, and it is compared with the reference voltage VREF1. Based on the comparison result, the conduction current I is adjusted. D Constant current control is performed. Specifically, the on-state current I of the device under test (DUT) is detected by the current detection module 130. D The detection voltage VID is obtained; the detection voltage VID and the reference voltage VREF1 are compared by the voltage comparison unit 141 and the comparison result is obtained, so as to control the switching of the device under test (DUT) by the pulse drive module 120, thereby realizing constant current control.

[0097] Step S3: Adjust the drain-source voltage V of the device under test (DUT) by adjusting the value of the power supply voltage VDD. DS The value of I is adjusted by adjusting the reference voltage VREF1 to adjust the on-current I of the device under test (DUT). D The value is determined to achieve the drain-source voltage V of the device under test (DUT) at a preset time. DS and conduction current I D Limit tests are performed to obtain the SOA curve of the device under test (DUT) under the corresponding test conditions. In practical applications, an oscilloscope is used to read the drain-source voltage V of the DUT. DS and conduction current I D Of course, other devices capable of reading voltage and current are also acceptable, and there are no restrictions on this.

[0098] Step S4: Compare the detection voltage VID and the threshold voltage VREF2. When the detection voltage VID is greater than the threshold voltage VREF2, control the auxiliary switch module 160 to turn off, thereby cutting off the current path of the device under test (DUT) and providing overcurrent protection after the DUT fails. Specifically, the overcurrent detection unit 151 compares the detection voltage VID and the threshold voltage VREF2, and generates an overcurrent protection signal when the detection voltage VID is greater than the threshold voltage VREF2; the isolation drive unit 153 generates an auxiliary turn-off signal based on the overcurrent protection signal to control the auxiliary switch module 160 to perform the turn-off operation.

[0099] In practical applications, after replacing the device under test (DUT) with a new one, steps S1 to S4 can be repeated to achieve the drain-source voltage V of the DUT at different preset times. DS and conduction current I D Limit value testing facilitates obtaining SOA curves of the device under test (DUT) under different test conditions; ideally, the new DUT and the original DUT should be manufactured in the same batch to ensure that the devices have the same specifications.

[0100] It should be noted that the test circuit and test method in this embodiment are applicable to power semiconductor devices in any package. In practice, the test circuit can be made into a test machine and one or more reserved package interfaces can be designed to accommodate the corresponding packaged device under test. In addition, the drive voltage VG, operating voltage VCC, reference voltage VREF1, threshold voltage VREF2, and power supply voltage VDD can be adjusted to adapt to different packaged devices under test, thereby completing the limit value test of the device under test and obtaining the corresponding SOA curve.

[0101] In summary, the test circuit and method of this invention allow for flexible adjustment of circuit parameters according to testing requirements. It is applicable to SOA testing of power semiconductor devices with different packages and specifications, offering a wide testing range and improving the diversity and accuracy of SOA testing, thus contributing to obtaining more realistic SOA curves. The circuit mainly consists of conventional electronic components such as resistors, capacitors, diodes, transistors, and operational amplifiers, resulting in low cost. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0102] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A test circuit suitable for SOA testing of power semiconductor devices, characterized in that, The test circuit includes: A module under test (DUT) is used to provide a device under test (DUT) for testing the limits of drain-source voltage and on-current when the DUT is turned on. A pulse drive module, connected to the module under test, is used to control the switching of the device under test based on the pulse signal and the comparison result. A current detection module, connected to the module under test, is used to detect the conduction current of the device under test and obtain the detection voltage; A constant current control module is connected between the current detection module and the pulse drive module. It is used to compare the detected voltage and the reference voltage, and to perform constant current control on the conduction current according to the comparison result. The value of the conduction current is adjusted by adjusting the value of the reference voltage. An overcurrent drive module, connected to the current detection module, is used to generate a synchronous turn-on signal based on the pulse signal, and to compare the detected voltage with a threshold voltage, and generate an auxiliary turn-off signal when the detected voltage is greater than the threshold voltage. An auxiliary switch module is connected between the overcurrent drive module and the device under test (DUT). It is used to perform an on operation according to the synchronous on signal to achieve synchronous on-time with the DUT, and to perform an off operation according to the auxiliary off signal to cut off the current path of the DUT. A power supply module, connected to the auxiliary switch module, is used to provide a power supply voltage and adjust the drain-source voltage of the device under test by adjusting the value of the power supply voltage.

2. The test circuit according to claim 1, characterized in that, The module under test includes a device under test (DUT) and a first resistor. The control terminal of the DUT is connected to the output terminal of the pulse drive module. The first terminal of the DUT is connected to a floating ground and leads out a first voltage measurement point and a current measurement point. The second terminal of the DUT is connected to the detection terminal of the current detection module and leads out a second voltage measurement point. The first resistor is connected between the control terminal and the second terminal of the DUT. The drain-source voltage of the DUT is tested through the first voltage measurement point and the second voltage measurement point, and the on-current of the DUT is tested through the current measurement point.

3. The test circuit according to claim 1, characterized in that, The pulse drive module includes an upper switch, a lower switch, and a second resistor. The control terminals of the upper and lower switches are connected to each other and to the output terminal of the pulse signal and the constant current control module. The first terminal of the upper switch is connected to the driving voltage, and the second terminal of the upper switch is connected to the first terminal of the lower switch and the first terminal of the second resistor. The second terminal of the lower switch is connected to control ground, and the second terminal of the second resistor serves as the output terminal of the pulse drive module. Alternatively, the pulse drive module further includes a third resistor and a diode. The first terminal of the third resistor is connected to the second terminal of the upper switch, the second terminal of the third resistor is connected to the anode of the diode, and the cathode of the diode is connected to the second terminal of the second resistor.

4. The test circuit according to claim 1, characterized in that, The current detection module includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and a first operational amplifier. The first end of the fourth resistor is connected to the first end of the fifth resistor and serves as the detection terminal of the current detection module. The second end of the fourth resistor is connected to the first end of the sixth resistor and connected to power ground. The second end of the fifth resistor is connected to the first input terminal of the first operational amplifier and connected to control ground via the seventh resistor. The second end of the sixth resistor is connected to the second input terminal of the first operational amplifier and connected to the output terminal of the first operational amplifier via the eighth resistor. The output terminal of the first operational amplifier is connected to the first end of the ninth resistor. The second end of the ninth resistor serves as the output terminal of the current detection module. The number of fourth resistors is greater than or equal to one; when the number is greater than one, the fourth resistors are connected in parallel. Alternatively, the current detection module further includes a first capacitor connected in parallel across the four fourth resistors.

5. The test circuit according to claim 1, characterized in that, The constant current control module includes a voltage comparison unit and a reference providing unit; The voltage comparison unit includes a first comparator and a tenth resistor. The first input terminal of the first comparator is connected to the output terminal of the reference providing unit, the second input terminal of the first comparator is connected to the output terminal of the current detection module, the output terminal of the first comparator is connected to the first terminal of the tenth resistor, and the second terminal of the tenth resistor serves as the output terminal of the constant current control module. Alternatively, the voltage comparison unit further includes at least one of a first filter and a second filter, wherein: the first filter includes an eleventh resistor and a second capacitor, the second capacitor is connected in parallel across the eleventh resistor, the first terminal of the eleventh resistor is connected to the first input terminal of the first comparator, and the second terminal of the eleventh resistor is connected to control ground; the second filter includes a twelfth resistor, a third capacitor, and a fourth capacitor, the third capacitor is connected in parallel across the twelfth resistor, the first terminal of the twelfth resistor is connected to the output terminal of the current detection module and connected to control ground via the fourth capacitor, and the second terminal of the twelfth resistor is connected to the second input terminal of the first comparator. The reference providing unit includes a first adjustable potentiometer, a thirteenth resistor, and a fourteenth resistor. The first terminal of the first adjustable potentiometer is connected to the operating voltage, and the second terminal of the first adjustable potentiometer is connected to the control ground. The sliding terminal of the first adjustable potentiometer is connected to the first terminal of the fourteenth resistor via the thirteenth resistor, and the second terminal of the fourteenth resistor serves as the output terminal of the reference providing unit. Alternatively, the reference providing unit may further include a fifth capacitor and a sixth capacitor, which are respectively connected between the two ends of the thirteenth resistor and the control ground.

6. The test circuit according to claim 1, characterized in that, The overcurrent drive module includes: An overcurrent detection unit, connected to the current detection module, is used to compare the detected voltage with the threshold voltage and generate an overcurrent protection signal when the detected voltage is greater than the threshold voltage. A threshold providing unit, connected to the overcurrent detection unit, is used to provide the threshold voltage; An isolation drive unit, connected to the overcurrent detection unit, is used to generate the synchronous turn-on signal based on the pulse signal and the auxiliary turn-off signal based on the overcurrent protection signal.

7. The test circuit according to claim 6, characterized in that, The overcurrent detection unit includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a second comparator, and a latch. The first input terminal of the second comparator is connected to the output terminal of the current detection module via the fifteenth resistor. The second input terminal of the second comparator is connected to the output terminal of the threshold providing unit. The output terminal of the second comparator is connected to the clock terminal of the latch via the sixteenth resistor. The data terminal of the latch is connected to the operating voltage via the seventeenth resistor. The inverting output terminal of the latch is connected to the first terminal of the eighteenth resistor. The second terminal of the eighteenth resistor serves as the output terminal of the overcurrent detection unit. Alternatively, the overcurrent detection unit further includes at least one of a seventh capacitor and an eighth capacitor, wherein: the first terminal of the seventh capacitor is connected to the first input terminal of the second comparator, and the second terminal of the seventh capacitor is connected to control ground; the first terminal of the eighth capacitor is connected to the second input terminal of the second comparator, and the second terminal of the eighth capacitor is connected to control ground.

8. The test circuit according to claim 6, characterized in that, The threshold providing unit includes a second adjustable potentiometer, a nineteenth resistor, a twentieth resistor, and a second operational amplifier. The first terminal of the second adjustable potentiometer is connected to the operating voltage, and the second terminal of the second adjustable potentiometer is connected to control ground. The sliding terminal of the second adjustable potentiometer is connected to the first input terminal of the second operational amplifier via the nineteenth resistor. The second input terminal of the second operational amplifier is connected to its output terminal, and the output terminal of the second operational amplifier is connected to the first terminal of the twentieth resistor. The second terminal of the twentieth resistor serves as the output terminal of the threshold providing unit. Alternatively, the threshold providing unit may further include a ninth capacitor and a tenth capacitor, which are respectively connected between the two ends of the nineteenth resistor and the control ground.

9. The test circuit according to claim 6, characterized in that, The isolation drive unit includes a 21st resistor, a 22nd resistor, a 23rd resistor, an optocoupler, and a voltage converter. The first end of the 21st resistor is connected to the pulse signal and the output of the overcurrent detection unit. The second end of the 21st resistor is connected to the first end of the light-emitting device in the optocoupler and connected to the control ground via the 22nd resistor. The second end of the light-emitting device in the optocoupler is connected to the control ground. The first end of the light-receiving device in the optocoupler is connected to the first end of the 23rd resistor. The second end of the light-receiving device in the optocoupler is connected to the floating ground. The second end of the 23rd resistor serves as the output of the overcurrent drive module. The voltage converter is used to convert the drive voltage into a floating voltage to power the optocoupler and to convert the control ground into a floating ground.

10. The test circuit according to claim 1, characterized in that, The auxiliary switch module includes at least one auxiliary switch unit. When the number of auxiliary switch units is greater than one, the auxiliary switch units are connected in parallel. The auxiliary switch unit includes an auxiliary switch transistor, a 24th resistor, and a 25th resistor. The control terminal of the auxiliary switch transistor is connected to the output terminal of the overcurrent drive module via the 24th resistor. The first terminal of the auxiliary switch transistor is connected to the power supply voltage, and the second terminal of the auxiliary switch transistor is connected to the floating ground and connected to its control terminal via the 25th resistor.

11. The test circuit according to claim 1, characterized in that, The power supply module includes an adjustable power supply and an eleventh capacitor. The positive terminal of the adjustable power supply generates the power supply voltage, and the negative terminal of the adjustable power supply is connected to power ground. The eleventh capacitor is connected in parallel across the two ends of the adjustable power supply. Alternatively, the power supply module further includes a twenty-sixth resistor and a first LED. The first end of the twenty-sixth resistor is connected to the positive terminal of the adjustable power supply, the second end of the twenty-sixth resistor is connected to the anode terminal of the first LED, and the cathode terminal of the first LED is connected to power ground.

12. The test circuit according to any one of claims 1 to 11, characterized in that, The test circuit further includes a voltage supply module for providing drive voltage and operating voltage; wherein, the voltage supply module includes an adjustable DC source, a linear regulator, a third adjustable potentiometer, a twenty-seventh resistor, a twelfth capacitor, and a thirteenth capacitor; the positive terminal of the adjustable DC source is connected to the first terminal of the twelfth capacitor and the input terminal of the linear regulator, serving as the drive voltage output terminal of the voltage supply module; the negative terminal of the adjustable DC source is connected to control ground; the output terminal of the linear regulator is connected to the first terminal of the third adjustable potentiometer and the first terminal of the twenty-seventh resistor, serving as the operating voltage output terminal of the voltage supply module; the second terminal of the third adjustable potentiometer is connected to control ground; the sliding terminal of the third adjustable potentiometer is connected to the second terminal of the twenty-seventh resistor and the common terminal of the linear regulator; the second terminal of the twenty-seventh resistor is also connected to control ground via the thirteenth capacitor; or, the voltage supply module further includes at least one of an input filter, an output filter, and an operating indicator. The input filter includes a first inductor, a second inductor, a fourteenth capacitor, and a fifteenth capacitor. The first end of the first inductor is connected to the positive terminal of the adjustable DC source. The second end of the first inductor is connected to the first end of the twelfth capacitor and the input terminal of the linear regulator. The first end of the second inductor is connected to the negative terminal of the adjustable DC source, and the second end of the second inductor is connected to control ground. The fourteenth capacitor is connected between the first end of the first inductor and the first end of the second inductor. The fifteenth capacitor is connected between the second end of the first inductor and the second end of the second inductor. The output filter includes at least one sixteenth capacitor, which is connected in parallel between the first and second terminals of the third adjustable potentiometer. The operating indicator includes a twenty-eighth resistor and a second LED. The first end of the twenty-eighth resistor is connected to the output terminal of the linear regulator, and the second end of the twenty-eighth resistor is connected to the anode terminal of the second LED. The cathode terminal of the second LED is connected to control ground.

13. A test method based on the test circuit described in any one of claims 1 to 12, characterized in that, The testing method includes: The module under test and the auxiliary switch module are synchronously turned on by a pulse signal, wherein the pulse duration of the pulse signal is a preset time; The on-current of the device under test in the module under test is detected and the detection voltage is obtained. The detection voltage is compared with the reference voltage and the on-current is controlled by constant current based on the comparison result. The drain-source voltage of the device under test is adjusted by adjusting the power supply voltage, and the on-current of the device under test is adjusted by adjusting the reference voltage, thereby achieving the limit value test of the drain-source voltage and on-current of the device under test under a preset time. The detection voltage and the threshold voltage are compared, and when the detection voltage is greater than the threshold voltage, the auxiliary switch module is controlled to turn off to cut off the current path of the device under test.

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