A test circuit

Abstract

The present invention provides a test circuit, comprising: a unit to be tested, a first capacitor, a second capacitor, an electronic fuse, and an opening and closing control unit; the first end of the unit to be tested is connected to the upper plate of the first capacitor, and the second end is connected to the lower plate of the first capacitor and the lower plate of the second capacitor; the electronic fuse is connected between the upper plate of the first capacitor and the upper plate of the second capacitor, and is controlled by an opening and closing control signal; the opening and closing control unit is used to sample the electrical signal of the electronic fuse to obtain a sampling signal, and to generate an opening and closing control signal based on a comparison result of the sampling signal and a reference signal, so as to control the electronic fuse to close when the unit to be tested is operating normally and to open when the unit to be tested is operating abnormally; wherein the capacitance of the first capacitor is smaller than that of the second capacitor. The test circuit provided by the present invention solves the problem of tube explosion caused by component failure in existing high-voltage testing.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor device testing, and in particular to a testing circuit. Background Art

[0002] During the testing of semiconductor high-voltage power devices (such as Si MOSFETs, IGBTs, and SiC MOSFETs), especially during short-circuit withstand tests, device failures are common, often accompanied by high voltage and high current shocks on the bus capacitors, until the capacitors discharge or the device explodes. During high-voltage testing, the energy in the bus capacitors is often very large, and eventual device explosion is often unavoidable. This explosion is accompanied by splashing of the plastic casing, so adequate physical protection is essential.

[0003] In view of this, how to prevent semiconductor high-voltage power devices from exploding due to device failure during testing is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a test circuit for solving the problem of tube explosion often occurring due to component failure in the existing high-voltage test.

[0005] To achieve the above-mentioned and other related objects, the present invention provides a test circuit, which includes: a unit to be tested, a first capacitor, a second capacitor, an electronic fuse, and an opening and closing control unit;

[0006] The first end of the unit under test is connected to the upper plate of the first capacitor, and the second end is connected to the lower plate of the first capacitor and the lower plate of the second capacitor; the electronic fuse is connected between the upper plate of the first capacitor and the upper plate of the second capacitor, and is controlled by an opening and closing control signal;

[0007] The opening and closing control unit is used to sample the electrical signal of the electronic fuse to obtain a sampling signal, and generate the opening and closing control signal according to a comparison result of the sampling signal and a reference signal, so as to control the electronic fuse to close when the unit under test is working normally, and to control the electronic fuse to open when the unit under test is working abnormally;

[0008] The capacitance of the first capacitor is smaller than the capacitance of the second capacitor.

[0009] Optionally, the opening and closing control unit includes: a sampling module and a signal generating module;

[0010] The sampling module is used to sample the electrical signal of the electronic fuse to obtain a sampling signal, and compare the sampling signal with the reference signal to generate a comparison result;

[0011] The signal generating module is connected to the output end of the sampling module, and is used to shield the input signal and generate an opening control signal when the comparison result is a low level, and to generate a closing control signal according to the input signal when the comparison result is a high level.

[0012] Optionally, the electrical signal includes a current signal; the sampling module includes: a first resistor, a second resistor, a third resistor, a fourth resistor and a first comparator;

[0013] The first resistor is connected between the electronic fuse and the first capacitor; the first end of the second resistor is connected to the connection node between the electronic fuse and the first resistor, and the second end is connected to the inverting input terminal of the first comparator; the third resistor and the fourth resistor are connected in series and connected between a first reference voltage and the upper plate of the first capacitor; the non-inverting input terminal of the first comparator is connected to the connection node between the third resistor and the fourth resistor, and the output terminal serves as the output terminal of the sampling module.

[0014] Optionally, the electrical signal includes a voltage signal; the sampling module includes: a fifth resistor, a sixth resistor, a seventh resistor and a second comparator;

[0015] The fifth resistor is connected between the electronic fuse and the first capacitor; the sixth resistor and the seventh resistor are connected in series and connected between the upper plate of the second capacitor and the upper plate of the first capacitor; the non-inverting input terminal of the second comparator is connected to the second reference voltage, the inverting input terminal is connected to the connection node of the sixth resistor and the seventh resistor, and the output terminal serves as the output terminal of the sampling module.

[0016] Optionally, the sampling module further includes: a first voltage regulator tube connected in parallel to both ends of the seventh resistor.

[0017] Optionally, the electrical signal includes a current signal and a voltage signal; the sampling module includes: an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a third comparator, a fourth comparator and an AND logic gate;

[0018] The eighth resistor is connected between the electronic fuse and the first capacitor; the first end of the ninth resistor is connected to the connection node of the electronic fuse and the eighth resistor, and the second end is connected to the inverting input terminal of the third comparator; the tenth resistor and the eleventh resistor are connected in series and connected between the third reference voltage and the upper plate of the first capacitor; the non-inverting input terminal of the third comparator is connected to the connection node of the tenth resistor and the eleventh resistor, and the output terminal is connected to the first input terminal of the AND logic gate; the twelfth resistor and the thirteenth resistor are connected in series and connected between the upper plate of the second capacitor and the upper plate of the first capacitor; the non-inverting input terminal of the fourth comparator is connected to the fourth reference voltage, the inverting input terminal is connected to the connection node of the twelfth resistor and the thirteenth resistor, and the output terminal is connected to the second input terminal of the AND logic gate; the output terminal of the AND logic gate serves as the output terminal of the sampling module.

[0019] Optionally, the sampling module further includes: a second voltage regulator tube connected in parallel to both ends of the thirteenth resistor.

[0020] Optionally, the signal generating module includes: a fourteenth resistor, a signal generator and a push-pull driver;

[0021] The input end of the signal generator is connected to the output end of the sampling module and is connected to the input signal via the fourteenth resistor, and is used to shield the input signal and generate an open drive signal when the comparison result is a low level, and amplify the input signal to generate a closed drive signal when the comparison result is a high level;

[0022] The push-pull driver is connected to the output end of the signal generator, and is used to perform push-pull output according to the opening drive signal or the closing drive signal to generate the opening control signal or the closing control signal.

[0023] Optionally, the push-pull driver includes: a fifteenth resistor, a sixteenth resistor, a first transistor, and a second transistor;

[0024] The first end of the fifteenth resistor is connected to the output end of the signal generator, and the second end is connected to the control end of the first transistor and the control end of the second transistor; the first end of the first transistor is connected to the first end of the second transistor and to the first end of the sixteenth resistor, and the second end is connected to the operating voltage; the second end of the second transistor is connected to the upper plate of the first capacitor; the second end of the sixteenth resistor serves as the output end of the push-pull driver.

[0025] Optionally, the push-pull driver further includes: a seventeenth resistor and a third voltage-stabilizing diode;

[0026] The seventeenth resistor and the third voltage-stabilizing diode are both connected in parallel between the second end of the sixteenth resistor and the second end of the second transistor.

[0027] Optionally, the unit under test includes: a power device, a control end connected to a test control signal, a first end serving as a first end of the unit under test connected to an upper plate of the first capacitor, and a second end serving as a second end of the unit under test connected to a lower plate of the first capacitor and a lower plate of the second capacitor;

[0028] Alternatively, the unit to be tested includes: a first power device, a second power device and an inductor; the control end of the first power device is connected to a first test control signal, the first end is connected to the upper plate of the first capacitor as the first end of the unit to be tested, and the second end is connected to the first end of the second power device; the control end of the second power device is connected to a second test control signal, the second end is connected to the lower plate of the first capacitor and the lower plate of the second capacitor as the second end of the unit to be tested; the inductor is connected in parallel between the first end and the second end of the first power device.

[0029] As described above, the test circuit of the present invention, through the design of the unit under test, the first capacitor, the second capacitor, the electronic fuse, and the opening and closing control unit, realizes that when the unit under test is operating normally, the electronic fuse is closed, and the first capacitor and the second capacitor are used to power the unit under test. When the unit under test is operating abnormally, the electronic fuse opens, cutting off the power supply link of the large-capacity second capacitor, and only the small-capacity first capacitor will be discharged by the unit under test, thereby avoiding the risk of explosion of the relevant components in the unit under test due to failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The first schematic diagram of the test circuit of the present invention is shown, wherein the sampling module samples the current signal of the electronic fuse.

[0031] Figure 2 The second schematic diagram of the test circuit of the present invention is shown, wherein the sampling module samples the voltage signal of the electronic fuse.

[0032] Figure 3 The third schematic diagram of the test circuit of the present invention is shown, wherein the sampling module samples the current signal and the voltage signal of the electronic fuse.

[0033] Component number description

[0034] 100 units under test

[0035] 200 electronic fuse

[0036] 300 opening and closing control unit

[0037] 310 Sampling Module

[0038] 320 signal generation module

[0039] 321 Signal Generator

[0040] 322 Push-Pull Driver DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] See also Figures 1 to 3 It should be noted that the illustrations provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation, the form, quantity, and proportion of each component in actual implementation may be arbitrarily changed, and the component layout may also be more complex.

[0043] like Figures 1 to 3 As shown, this embodiment provides a test circuit, which includes: a unit to be tested 100 , a first capacitor C1 , a second capacitor C2 , an electronic fuse 200 , and a switching control unit 300 .

[0044] A first end of the unit under test 100 is connected to the upper plate of the first capacitor C1 , and a second end thereof is connected to the lower plate of the first capacitor C1 and the lower plate of the second capacitor C2 .

[0045] As an example, Figure 1 As shown, the unit under test 100 includes: a power device M1; the control end of the power device M1 is connected to the test control signal, the first end is connected to the upper plate of the first capacitor C1 as the first end of the unit under test 100, and the second end is connected to the lower plate of the first capacitor C1 and the lower plate of the second capacitor C2 as the second end of the unit under test 100.

[0046] Furthermore, the unit under test 100 also includes: an eighteenth resistor R18 and a fourth voltage-stabilizing diode ZD4; wherein the eighteenth resistor R18 and the fourth voltage-stabilizing diode ZD4 are both connected in parallel between the control end and the second end of the power device M1, and are used to perform voltage stabilization operation when the voltage of the input test control signal is too high, thereby preventing the power device M1 from being damaged by the high voltage. At the same time, it can also prevent the front-stage driver from being damaged due to backflow when the power device M1 fails.

[0047] Among them, the power device M1 includes a high-voltage Si MOSFET device, a high-voltage SiC MOSFET device, a high-voltage IGBT device, etc.; optionally, the power device M1 is a high-voltage N-type device, such as a high-voltage N-type Si MOSFET device. In this case, the control end is the gate end, the first end is the drain end, and the second end is the source end.

[0048] In this embodiment, when the power device M1 is controlled to be turned on by the test control signal, the capacitor discharge can be used to perform a short circuit test on the power device M1.

[0049] As another example, Figure 2 and Figure 3 As shown, the unit under test 100 includes: a first power device M1, a second power device M2 and an inductor L; the control end of the first power device M1 is connected to a first test control signal, the first end is connected to the upper plate of the first capacitor C1 as the first end of the unit under test 100, and the second end is connected to the first end of the second power device M2; the control end of the second power device M2 is connected to a second test control signal, the second end is connected to the lower plate of the first capacitor C1 and the lower plate of the second capacitor C2 as the second end of the unit under test 100; the inductor L is connected in parallel between the first end and the second end of the first power device M1.

[0050] Furthermore, the unit under test 100 also includes: a nineteenth resistor R19, a twentieth resistor R20, a fifth voltage-stabilizing diode ZD5 and a sixth voltage-stabilizing diode ZD6; wherein the nineteenth resistor R19 and the fifth voltage-stabilizing diode ZD5 are both connected in parallel between the control end and the second end of the first power device M1, and the twentieth resistor R20 and the sixth voltage-stabilizing diode ZD6 are both connected in parallel between the control end and the second end of the second power device M2, and are used to perform voltage stabilization operation when the voltage of the corresponding input test control signal is too high, so as to avoid damage to the corresponding power device due to high voltage, and at the same time, to avoid damage to the pre-stage driver due to backflow when the corresponding power device fails.

[0051] Among them, the first power device M1 and the second power device M2 both include high-voltage Si MOSFET devices, high-voltage SiCMOSFET devices, high-voltage IGBT devices, etc.; optionally, the first power device M1 and the second power device M2 are high-voltage N-type devices, such as high-voltage N-type Si MOSFET devices. In this case, the control end is the gate end, the first end is the drain end, and the second end is the source end.

[0052] In this embodiment, the first power device M1 is controlled to be continuously off by a first test control signal, and a second test control signal is used to provide a double pulse to the second power device M2. When the first pulse arrives, the second power device M2 is turned on, and the current in the inductor L is linearly increased by capacitor discharge. When the first pulse ends, the second power device M2 is turned off, and the current in the inductor L is freewheeled by the body diode of the first power device M1. When the second pulse arrives, the second power device M2 is turned on again, and the body diode of the first power device M1 reverse recovers. In this way, a double pulse test can be completed for the first power device M1 or the second power device M2, such as the reverse recovery performance test of the body diode of the first power device M1 and the switching performance test of the second power device M2.

[0053] The upper plate of the first capacitor C1 and the upper plate of the second capacitor C2 are connected through the electronic fuse 200. The upper plate of the first capacitor C1 is also connected to the first end of the unit under test 100. The lower plate of the first capacitor C1 and the lower plate of the second capacitor C2 are both connected to the second end of the unit under test 100.

[0054] Specifically, the capacitance of the first capacitor C1 is smaller than that of the second capacitor C2. The first capacitor C1 is a small-capacity capacitor (e.g., C1 < 100 μF) and primarily serves as a voltage stabilizer and filter. The second capacitor C2 is a large-capacity capacitor (e.g., C2 > 10*C1) and primarily provides energy. In practical applications, the capacitance of the first capacitor C1 is typically less than 20 μF, while the capacitance of the second capacitor C2 is typically several hundred μF. Furthermore, in the circuit layout, the first capacitor C1 should be placed close to the unit under test 100 to minimize parasitic inductance and ensure a very low inductance in the test main loop.

[0055] By dividing a single busbar capacitor into two parts, a first capacitor C1 and a second capacitor C2, and providing an electronic fuse between the first capacitor C1 and the second capacitor C2; if the unit under test 100 is abnormal, the electronic fuse 200 can be quickly opened to cut off the power supply link of the large-capacity second capacitor C2. In this way, only the small-capacity first capacitor C1 will be discharged by the failed device, but due to its small energy, the failed device will not explode.

[0056] The electronic fuse 200 is connected between the upper plate of the first capacitor C1 and the upper plate of the second capacitor C2 and is controlled by an opening and closing control signal. When the unit under test 100 is operating normally, it is closed to continuously supply power through the large-capacity second capacitor C2. When the unit under test 100 is operating abnormally, it is opened to cut off the power supply link of the large-capacity second capacitor C2 to prevent the unit from exploding.

[0057] Specifically, the electronic fuse 200 is implemented using a high-speed, high-voltage device, such as a high-voltage SiC MOSFET device, a high-voltage IGBT device, etc.; taking the electronic fuse 200 as a high-voltage IGBT device as an example, the gate of the high-voltage IGBT device is connected to the opening and closing control signal, the collector is connected to the upper plate of the second capacitor C2, and the emitter is connected to the upper plate of the first capacitor C1.

[0058] The use of high-speed, high-voltage devices to implement the function of the electronic fuse 200 can achieve rapid opening (operation time less than 2μs) under high voltage and high current, and at the same time, it can have extremely low parasitic inductance (e.g., a few nH to tens of nH), thereby not affecting the test main circuit inductance and test waveform. After all, the use of other physical disconnection devices such as relays has two problems: first, the overcurrent disconnection response time is too long (more than ms level), which cannot play a protective role (the failed device has exploded before it is disconnected); second, the parasitic inductance itself is too large, which seriously affects the device test waveform.

[0059] The opening and closing control unit 300 is used to sample the electrical signal of the electronic fuse 200 to obtain a sampling signal, and generate an opening and closing control signal based on the comparison result of the sampling signal and the reference signal. This is to control the electronic fuse 200 to close when the unit under test 100 is operating normally, and to control the electronic fuse 200 to open when the unit under test 100 is operating abnormally. The opening and closing control signal includes an opening control signal and a closing control signal.

[0060] Specifically, the opening and closing control unit 300 includes a sampling module 310 and a signal generating module 320 .

[0061] The sampling module 310 is used to sample the electrical signal of the electronic fuse 200 to obtain a sampling signal, and compare the sampling signal with a reference signal to generate a comparison result; wherein the electrical signal includes a current signal and / or a voltage signal.

[0062] As a first example, Figure 1 As shown, the electrical signal includes a current signal; in this case, the sampling module 310 includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first comparator CMP1; the first resistor R1 is connected between the electronic fuse 200 and the first capacitor C1; the first end of the second resistor R2 is connected to the connection node between the electronic fuse 200 and the first resistor R1, and the second end is connected to the inverting input terminal of the first comparator CMP1; the third resistor R3 and the fourth resistor R4 are connected in series and connected between the first reference voltage VREF1 and the upper plate of the first capacitor C1; the non-inverting input terminal of the first comparator CMP1 is connected to the connection node between the third resistor R3 and the fourth resistor R4, and the output terminal serves as the output terminal of the sampling module 310.

[0063] The first resistor R1 is a small resistance resistor (such as a few mΩ), and the number thereof can be one or more (greater than or equal to 2). When the number thereof is more than one, the multiple first resistors R1 are arranged in parallel, and an electronic fuse 200 needs to be added accordingly. The multiple electronic fuses 200 are also arranged in parallel, such as Figure 1 However, it should be noted that when the number of electronic fuses 200 is greater than one, the electrical signal sampling is performed on only one of the electronic fuses 200 .

[0064] In this embodiment, the first resistor R1 and the second resistor R2 are used to sample the current flowing through the electronic fuse 200 to obtain a sampling signal, and the third resistor R3 and the fourth resistor R4 are used to divide the first reference voltage VREF1 to obtain a reference signal; the first comparator CMP1 compares the sampling signal with the reference signal;

[0065] If the power device in the unit under test 100 works normally, the current flowing through the electronic fuse 200 is small, that is, the sampling signal is small. At this time, the sampling signal is smaller than the reference signal, and the first comparator CMP1 outputs a high level.

[0066] If the power device in the unit under test 100 fails, the current flowing through the electronic fuse 200 will increase sharply, that is, the sampling signal will increase sharply. At this time, the sampling signal is greater than the reference signal, and the first comparator CMP1 outputs a low level.

[0067] It should be noted that the third resistor R3 can be a fixed resistor or an adjustable resistor. In practical applications, the third resistor R3 can be an adjustable resistor to achieve the adjustment of the reference signal.

[0068] As a second example, Figure 2 As shown, the electrical signal includes a voltage signal; in this case, the sampling module 310 includes: a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and a second comparator CMP2; the fifth resistor R5 is connected between the electronic fuse 200 and the first capacitor C1; the sixth resistor R6 and the seventh resistor R7 are connected in series and connected between the upper plate of the second capacitor C2 and the upper plate of the first capacitor C1; the non-inverting input terminal of the second comparator CMP2 is connected to the second reference voltage VREF2, the inverting input terminal is connected to the connection node of the sixth resistor R6 and the seventh resistor R7, and the output terminal serves as the output terminal of the sampling module 310.

[0069] The fifth resistor R5 is a small resistance resistor (e.g., several mΩ), and the number thereof can be one or more (greater than or equal to 2). When the number thereof is more than one, the plurality of fifth resistors R5 are arranged in parallel, and an electronic fuse 200 needs to be added accordingly. The plurality of electronic fuses 200 are also arranged in parallel, such as Figure 2However, it should be noted that when the number of electronic fuses 200 is greater than one, the electrical signal sampling is performed on only one of the electronic fuses 200 .

[0070] In this embodiment, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 are used to sample the voltage across the electronic fuse 200 to obtain a sampling signal, and the second reference voltage VREF2 is regarded as the reference signal; the second comparator CMP2 compares the sampling signal with the reference signal;

[0071] If the power device in the unit under test 100 works normally, the voltage across the electronic fuse 200 is small, that is, the sampling signal is small. At this time, the sampling signal is smaller than the reference signal, and the second comparator CMP2 outputs a high level.

[0072] If the power device in the unit under test 100 fails, the voltage across the electronic fuse 200 will increase sharply, that is, the sampling signal will increase sharply. At this time, the sampling signal is greater than the reference signal, and the second comparator CMP2 outputs a low level.

[0073] Furthermore, the sampling module 310 further includes: a first voltage regulator ZD1 connected in parallel to both ends of the seventh resistor R7 to perform a voltage regulation operation when the sampling signal voltage is too high, so as to prevent the high voltage from damaging the second comparator CMP2.

[0074] As a third example, Figure 3 As shown, the electrical signal includes a current signal and a voltage signal; in this case, the sampling module 310 includes: an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third comparator CMP3, a fourth comparator CMP4 and an AND logic gate AND; the eighth resistor R8 is connected between the electronic fuse 200 and the first capacitor C1; a first end of the ninth resistor R9 is connected to the connection node between the electronic fuse 200 and the eighth resistor R8, and a second end is connected to the inverting input terminal of the third comparator CMP3; the tenth resistor R10 and the eleventh resistor R11 are connected in series and connected to the third reference voltage VREF3 and the upper plate of the first capacitor C1; the non-inverting input terminal of the third comparator CMP3 is connected to the connection node of the tenth resistor R10 and the eleventh resistor R11, and the output terminal is connected to the first input terminal of the logic gate AND; the twelfth resistor R12 and the thirteenth resistor R13 are connected in series and connected between the upper plate of the second capacitor C2 and the upper plate of the first capacitor C1; the non-inverting input terminal of the fourth comparator CMP4 is connected to the fourth reference voltage VREF4, the inverting input terminal is connected to the connection node of the twelfth resistor R12 and the thirteenth resistor R13, and the output terminal is connected to the second input terminal of the logic gate AND; the output terminal of the logic gate AND serves as the output terminal of the sampling module 310.

[0075] The eighth resistor R8 is a small resistance resistor (e.g., several mΩ), and the number thereof can be one or more (greater than or equal to 2). When the number thereof is more than one, the plurality of eighth resistors R8 are arranged in parallel, and an electronic fuse 200 needs to be added accordingly. The plurality of electronic fuses 200 are also arranged in parallel, such as Figure 3 However, it should be noted that when the number of electronic fuses 200 is greater than one, the electrical signal sampling is performed on only one of the electronic fuses 200 .

[0076] In this embodiment, the eighth resistor R8 and the ninth resistor R9 are used to sample the current flowing through the electronic fuse 200 to obtain a first sampling signal, and the tenth resistor R10 and the eleventh resistor R11 are used to divide the third reference voltage VREF3 to obtain a first reference signal; the third comparator CMP3 compares the first sampling signal with the first reference signal;

[0077] If the power device in the unit under test 100 works normally, the current flowing through the electronic fuse 200 is small, that is, the sampling signal is small. At this time, the first sampling signal is smaller than the first reference signal, and the third comparator CMP3 outputs a high level.

[0078] If the power device in the unit under test 100 fails, the current flowing through the electronic fuse 200 will increase sharply, that is, the sampling signal will increase sharply. At this time, the first sampling signal is greater than the first reference signal, and the third comparator CMP3 outputs a low level.

[0079] At the same time, the eighth resistor R8, the twelfth resistor R12, and the thirteenth resistor R13 are used to sample the voltage across the electronic fuse 200 to obtain a second sampling signal, and the fourth reference voltage VREF4 is regarded as the second reference signal; the fourth comparator CMP4 compares the second sampling signal with the second reference signal;

[0080] If the power device in the unit under test 100 works normally, the voltage across the electronic fuse 200 is small, that is, the sampling signal is small. At this time, the second sampling signal is smaller than the second reference signal, and the fourth comparator CMP4 outputs a high level.

[0081] If the power device in the unit under test 100 fails, the voltage across the electronic fuse 200 will increase sharply, that is, the sampling signal will increase sharply. At this time, the second sampling signal is greater than the second reference signal, and the fourth comparator CMP4 outputs a low level.

[0082] The AND logic gate AND performs a logic AND process on the outputs of the third comparator CMP3 and the fourth comparator CMP4, so that when any comparator outputs a low level, the sampling module 310 outputs a low level. Simultaneous current sampling and voltage sampling can improve circuit control accuracy.

[0083] It should be noted that the tenth resistor R10 may be a fixed resistor or an adjustable resistor. In practical applications, the tenth resistor R10 may be an adjustable resistor to achieve the adjustability of the first reference signal.

[0084] Furthermore, the sampling module 310 further includes a second voltage regulator ZD2 connected in parallel to both ends of the thirteenth resistor R13 to perform voltage regulation when the voltage of the second sampling signal is too high, thereby preventing the high voltage from damaging the fourth comparator CMP4.

[0085] The signal generating module 320 is connected to the output end of the sampling module 310 and is used to shield the input signal and generate an open control signal when the comparison result is a low level, and to generate a close control signal according to the input signal when the comparison result is a high level.

[0086] As an example, the signal generating module 320 includes: a fourteenth resistor R14 , a signal generator 321 and a push-pull driver 322 .

[0087] in,

[0088] The input end of the signal generator 321 is connected to the output end of the sampling module 310 and is connected to the input signal via the fourteenth resistor R14, and is used to shield the input signal and generate an open drive signal when the comparison result is a low level, and amplify the input signal to generate a closed drive signal when the comparison result is a high level.

[0089] In this embodiment, if the comparison result is a low level, the input of signal generator 321 is pulled low, thereby shielding the input signal and causing signal generator 321 to output an open drive signal. If the comparison result is a high level, the input of signal generator 321 is unaffected, and signal generator 321 amplifies the input signal to generate a closed drive signal. In practical applications, signal generator 321 can be implemented using a chip that integrates amplification and isolation functions, achieving both high and low voltage isolation while performing signal amplification.

[0090] The push-pull driver 322 is connected to the output end of the signal generator 321 and is used for performing push-pull output according to the opening drive signal or the closing drive signal to generate an opening control signal or a closing control signal.

[0091] In which, the push-pull driver 322 includes: a fifteenth resistor R15, a sixteenth resistor R16, a first transistor Q1 and a second transistor Q2; the first end of the fifteenth resistor R15 is connected to the output end of the signal generator 321, and the second end is connected to the control end of the first transistor Q1 and the control end of the second transistor Q2; the first end of the first transistor Q1 is connected to the first end of the second transistor Q2 and to the first end of the sixteenth resistor R16, and the second end is connected to the operating voltage VCC; the second end of the second transistor Q2 is connected to the upper plate of the first capacitor C1; the second end of the sixteenth resistor R16 serves as the output end of the push-pull driver 322.

[0092] In this embodiment, the first transistor Q1 and the second transistor Q2 form a push-pull circuit; when the signal generator 321 outputs an open drive signal, the first transistor Q1 is turned off and the second transistor Q2 is turned on, thereby generating an open control signal to control the electronic fuse 200 to open; when the signal generator 321 outputs a close drive signal, the first transistor Q1 is turned on and the second transistor Q2 is turned off, thereby generating a close control signal to control the electronic fuse 200 to close.

[0093] Furthermore, the push-pull driver 322 also includes: a seventeenth resistor R17 and a third voltage-stabilizing diode ZD3; the seventeenth resistor R17 and the third voltage-stabilizing diode ZD3 are both connected in parallel between the second end of the sixteenth resistor R16 and the second end of the second transistor Q2, and are used to perform voltage stabilization operations when the voltage of the closed control signal is too high, thereby preventing the electronic fuse 200 from being damaged by the high voltage. At the same time, it can also prevent the transistors in the push-pull circuit from being damaged due to backflow when the unit under test 100 fails.

[0094] In summary, the test circuit of the present invention, through the design of a unit under test, a first capacitor, a second capacitor, an electronic fuse, and an opening and closing control unit, achieves a configuration in which the electronic fuse closes when the unit under test is operating normally, utilizing the first and second capacitors to power the unit under test. If the unit under test is operating abnormally, the electronic fuse opens, severing the power supply link to the large-capacity second capacitor. Only the small-capacity first capacitor is discharged by the unit under test, thereby avoiding the risk of explosion caused by failure of related components in the unit under test. Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial application value.

[0095] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A test circuit, characterized in that: The test circuit includes: a unit to be tested, a first capacitor, a second capacitor, an electronic fuse and an opening and closing control unit; The first end of the unit under test is connected to the upper plate of the first capacitor, and the second end is connected to the lower plate of the first capacitor and the lower plate of the second capacitor; the electronic fuse is connected between the upper plate of the first capacitor and the upper plate of the second capacitor, and is controlled by an opening and closing control signal; The opening and closing control unit is configured to sample an electrical signal from the electronic fuse to obtain a sampling signal, and generate the opening and closing control signal based on a comparison result of the sampling signal and a reference signal, so as to control the electronic fuse to close when the unit under test is operating normally, and to control the electronic fuse to open when the unit under test is operating abnormally, thereby cutting off the power supply link of the second capacitor, so that only the first capacitor will be discharged by the unit under test; The capacitance of the first capacitor is smaller than the capacitance of the second capacitor.

2. The test circuit according to claim 1, wherein: The opening and closing control unit includes: a sampling module and a signal generating module; The sampling module is used to sample the electrical signal of the electronic fuse to obtain a sampling signal, and compare the sampling signal with the reference signal to generate a comparison result; The signal generating module is connected to the output end of the sampling module, and is used to shield the input signal and generate an opening control signal when the comparison result is a low level, and to generate a closing control signal according to the input signal when the comparison result is a high level.

3. The test circuit according to claim 2, wherein: The electrical signal includes a current signal; the sampling module includes: a first resistor, a second resistor, a third resistor, a fourth resistor and a first comparator; The first resistor is connected between the electronic fuse and the first capacitor; the first end of the second resistor is connected to the connection node between the electronic fuse and the first resistor, and the second end is connected to the inverting input terminal of the first comparator; the third resistor and the fourth resistor are connected in series and connected between a first reference voltage and the upper plate of the first capacitor; the non-inverting input terminal of the first comparator is connected to the connection node between the third resistor and the fourth resistor, and the output terminal serves as the output terminal of the sampling module.

4. The test circuit according to claim 2, wherein: The electrical signal includes a voltage signal; the sampling module includes: a fifth resistor, a sixth resistor, a seventh resistor and a second comparator; The fifth resistor is connected between the electronic fuse and the first capacitor; the sixth resistor and the seventh resistor are connected in series and connected between the upper plate of the second capacitor and the upper plate of the first capacitor; the non-inverting input terminal of the second comparator is connected to the second reference voltage, the inverting input terminal is connected to the connection node of the sixth resistor and the seventh resistor, and the output terminal serves as the output terminal of the sampling module.

5. The test circuit according to claim 4, characterized in that: The sampling module further includes: a first voltage-stabilizing diode connected in parallel to both ends of the seventh resistor.

6. The test circuit according to claim 2, wherein: The electrical signal includes a current signal and a voltage signal; the sampling module includes: an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a third comparator, a fourth comparator and an AND logic gate; The eighth resistor is connected between the electronic fuse and the first capacitor; the first end of the ninth resistor is connected to the connection node of the electronic fuse and the eighth resistor, and the second end is connected to the inverting input terminal of the third comparator; the tenth resistor and the eleventh resistor are connected in series and connected between the third reference voltage and the upper plate of the first capacitor; the non-inverting input terminal of the third comparator is connected to the connection node of the tenth resistor and the eleventh resistor, and the output terminal is connected to the first input terminal of the AND logic gate; the twelfth resistor and the thirteenth resistor are connected in series and connected between the upper plate of the second capacitor and the upper plate of the first capacitor; the non-inverting input terminal of the fourth comparator is connected to the fourth reference voltage, the inverting input terminal is connected to the connection node of the twelfth resistor and the thirteenth resistor, and the output terminal is connected to the second input terminal of the AND logic gate; the output terminal of the AND logic gate serves as the output terminal of the sampling module.

7. The test circuit according to claim 6, characterized in that: The sampling module further includes: a second voltage-stabilizing diode connected in parallel to both ends of the thirteenth resistor.

8. The test circuit according to any one of claims 2 to 7, characterized in that: The signal generating module includes: a fourteenth resistor, a signal generator and a push-pull driver; The input end of the signal generator is connected to the output end of the sampling module and is connected to the input signal via the fourteenth resistor, and is used to shield the input signal and generate an open drive signal when the comparison result is a low level, and amplify the input signal to generate a closed drive signal when the comparison result is a high level; The push-pull driver is connected to the output end of the signal generator, and is used to perform push-pull output according to the opening drive signal or the closing drive signal to generate the opening control signal or the closing control signal.

9. The test circuit according to claim 8, characterized in that: The push-pull driver includes: a fifteenth resistor, a sixteenth resistor, a first transistor and a second transistor; The first end of the fifteenth resistor is connected to the output end of the signal generator, and the second end is connected to the control end of the first transistor and the control end of the second transistor; the first end of the first transistor is connected to the first end of the second transistor and to the first end of the sixteenth resistor, and the second end is connected to the operating voltage; the second end of the second transistor is connected to the upper plate of the first capacitor; the second end of the sixteenth resistor serves as the output end of the push-pull driver.

10. The test circuit according to claim 9, characterized in that: The push-pull driver further includes: a seventeenth resistor and a third voltage-stabilizing diode; The seventeenth resistor and the third voltage-stabilizing diode are both connected in parallel between the second end of the sixteenth resistor and the second end of the second transistor.

11. The test circuit according to claim 1, wherein: The unit under test comprises: a power device, a control end connected to a test control signal, a first end serving as a first end of the unit under test connected to an upper plate of the first capacitor, and a second end serving as a second end of the unit under test connected to a lower plate of the first capacitor and a lower plate of the second capacitor; Alternatively, the unit to be tested includes: a first power device, a second power device and an inductor; the control end of the first power device is connected to a first test control signal, the first end is connected to the upper plate of the first capacitor as the first end of the unit to be tested, and the second end is connected to the first end of the second power device; the control end of the second power device is connected to a second test control signal, the second end is connected to the lower plate of the first capacitor and the lower plate of the second capacitor as the second end of the unit to be tested; the inductor is connected in parallel between the first end and the second end of the first power device.

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