Test circuit, test device and test method

Abstract

The present application provides a test circuit, including a switch module, a measuring device and a floating control circuit, wherein the switch module is used to control the device under test to access the corresponding test circuit according to an action signal, so that the test circuit reaches a corresponding working state; the measuring device is connected to the switch module, and is used to measure the leakage current of the device under test; the floating control circuit is connected to both the switch module and the measuring device, and is used to act according to the received test trigger signal, and provide an action signal to the switch module to control the action of the switch module. In the above test circuit, by setting a floating control circuit, the switch coil is independently controlled and separated from the normal test circuit, which can minimize the influence of the switch on the test circuit. In addition, the test circuit can flexibly realize the switching of test circuits with different parameters by turning on and off the switch, thereby improving the efficiency of the test and meeting the needs of large-scale industrial production.

Description

Technical Field

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

[0002] In integrated circuit testing, especially in the testing of semiconductor discrete devices (such as MOSFET, triode, IGBT, etc.), it is usually necessary to perform leakage current testing on the device under test (hereinafter referred to as DUT, Device Under Test). In the actual testing process, other parameter tests besides leakage current will be performed on the same fixture at the same time, which requires adding switching circuits when designing test circuits to switch and test multiple test circuits.

[0003] Usually, the method used for switching the test circuit is to connect a series switch, and the switching of the test circuit is achieved by turning the switch on / off. However, since leakage resistance cannot be avoided between the switch coil and the contact, the leakage current caused by the switch leakage resistance cannot be ignored in the leakage current test of semiconductor discrete devices at the nanoampere level or even the picoampere level. In large-scale industrial production, in order to improve the test efficiency, the test equipment (including test power supply, test instrument, etc.) is often a complete set of equipment, and the test experiment is carried out by leading out the test probe. Therefore, in the semiconductor micro-current test circuit with a switch, the test equipment will inevitably introduce the switch leakage current interference, which seriously affects the accuracy of the semiconductor test. How to eliminate the switch leakage current has become an urgent problem to be solved in integrated circuit testing. Summary of the invention

[0004] Based on this, it is necessary to provide a test circuit, a test device and a test method to address the above technical problems, so as to solve the problem of inaccurate leakage current test of the device under test (DUT) caused by switch leakage current in the existing semiconductor test circuit including a switch switching circuit.

[0005] On the one hand, the present application provides a test circuit, including a switch module, a measuring device and a floating control circuit, wherein the switch module is used to control the device under test to connect to the corresponding test circuit according to a switch action signal; the measuring device is connected to the switch module and is used to measure the leakage current of the device under test; the floating control circuit is connected to the switch module and the measuring device and is used to act according to the received test trigger signal and provide the switch action signal to the switch module to control the action of the switch module.

[0006] In the test circuit provided in the above embodiment, a floating control circuit is set to independently control the switch coil and separate it from the normal test circuit, which can minimize the impact of the switch on the test circuit. In addition, an isolated power supply with a voltage value much smaller than the test power supply is set in the floating control circuit to provide a working power supply for the switch coil, which can greatly reduce the voltage across the switch leakage resistance, and then greatly reduce the impact of the switch leakage current on the leakage current of the device to be tested. In addition, the test circuit can flexibly switch test circuits with different parameters by turning on and off the switch, thereby improving the test efficiency and meeting the needs of large-scale industrial production.

[0007] In one embodiment, the switch action signal includes a leakage current test action signal and other test action signals, and the switch module includes:

[0008] A first switch is configured such that: a first contact is connected to a first power source through the measuring device, a second contact is connected to the device under test, and a first coil port and a second coil port are both connected to the floating control circuit;

[0009] The first switch is further configured to: close according to the leakage current test action signal to control the device under test to access the leakage current test circuit, or open according to the other test action signal to cut off the connection between the device under test and the leakage current test circuit;

[0010] A second switch is configured such that: a first contact is connected to a second contact of the first switch, a second contact is connected to other test circuits, and a first coil port and a second coil port are both connected to the floating control circuit;

[0011] The second switch is further configured to: be opened according to the leakage current test action signal to cut off the connection between the device under test and the other test circuit, or be closed according to the other test action signal to control the device under test to access the test loop of the other test circuit;

[0012] a third switch, configured as follows: a first contact connected to both the first power supply and the floating control circuit, a second contact connected to the second contact of the second switch, a first coil port connected to the second power supply, and a second coil port connected to the floating control circuit;

[0013] The third switch is further configured to be closed according to the leakage current test action signal to short-circuit the first contact of the second switch and the second contact of the second switch through the measuring device, or to be opened according to the other test action signal.

[0014] In one embodiment, the floating control circuit includes:

[0015] an isolated power supply, connected to the first power supply, the second power supply, the first switch, the second switch and the third switch, and used to provide a floating power supply for the first switch and the second switch;

[0016] an isolation driving circuit, connected to the first power supply, the first switch, the second switch, the third switch and the isolation power supply, and used for providing the action signal to the coil of the first switch and the coil of the second switch after being actuated, so as to actuate the first switch and the second switch;

[0017] The switch control circuit is connected to both the isolation drive circuit and the third switch, and is used to generate a control signal according to the test trigger signal to control the action of the isolation drive circuit to generate the action signal, or to control the action of the third switch.

[0018] In one embodiment, the isolated power supply is configured as:

[0019] The first end is connected to the isolation drive circuit, the second end is connected to the first coil port of the first switch, the first coil port of the second switch, the first contact of the third switch and the first power supply, the third end is grounded, and the fourth end is connected to the second power supply.

[0020] In one embodiment, the isolation driving circuit is configured as follows:

[0021] The first end is connected to the first end of the isolated power supply, the second end is connected to the second coil port of the second switch, the third end is connected to the second coil port of the first switch, and the fourth end, the fifth end and the sixth end are all connected to the switch control circuit.

[0022] In one embodiment, the switch control circuit is configured as follows:

[0023] The first end is connected to the second coil port of the third switch, the second end is connected to the sixth end of the isolation drive circuit, the third end is connected to the fifth end of the isolation drive circuit, the fourth end is connected to the fourth end of the isolation drive circuit, and the fifth end is grounded.

[0024] In one embodiment, the switch isolation control circuit includes a first controllable switch unit, a second controllable switch unit, a third controllable switch unit and a current limiting resistor;

[0025] The first controllable switch unit is configured as follows: a first pole is connected to the fourth end of the isolation drive circuit, and a second pole is grounded;

[0026] The second controllable switch unit is configured as follows: a first pole is connected to the fifth terminal of the isolation drive circuit, and a second pole is grounded;

[0027] The third controllable switch unit is configured as follows: a first pole is connected to the second coil port of the third switch, and a second pole is grounded;

[0028] The current limiting resistor is connected in series between the third power supply and the sixth terminal of the isolation driving circuit.

[0029] In one embodiment, it also includes:

[0030] The equipotential circuit unit is used to shield the external leakage current of the integrated circuit test circuit.

[0031] A second aspect of the present application provides a testing device, comprising:

[0032] The circuit as described in any of the preceding embodiments.

[0033] The third aspect of the present application provides a testing method, comprising:

[0034] Generate the leakage current test action signal according to the leakage current test trigger signal, control the first switch and the third switch to be closed, and control the second switch to be opened, so as to control the test circuit to enter the leakage current test working state;

[0035] The other test action signal is generated according to other test trigger signals, the first switch and the third switch are controlled to be opened, and the second switch is controlled to be closed, so as to control the test circuit to enter other test working states. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 This is a schematic diagram of the structure of a test circuit in one embodiment of the present application;

[0038] Figure 2 This is a structural schematic diagram of a test circuit in one embodiment of the present application;

[0039] Figure 3 This is a working principle diagram of a test circuit in one embodiment of the present application;

[0040] Figure 4 This is a working principle diagram of a test circuit in another embodiment of the present application;

[0041] Figure 5 This is a structural schematic diagram of a floating control circuit in one embodiment of the present application;

[0042] Figure 6 This is a structural schematic diagram of a test circuit in another embodiment of the present application;

[0043] Figure 7 This is a structural schematic diagram of a test circuit for a three-pin semiconductor discrete device in one embodiment of the present application;

[0044] Figure 8 This is a flow chart of a testing method in one embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0047] It can be understood that the terms "first", "second", etc. used in the present application can be used in this article to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0048] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0049] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0050] During the production of semiconductor devices, due to process limitations, certain defects will occur inside discrete semiconductor devices. These defects will produce parasitic effects when the discrete semiconductor devices are working, forming parasitic devices. This parasitic device will increase the leakage current of the device, which will lead to static power loss of the discrete semiconductor device, affecting the performance of the device. In severe cases, it may even cause circuit failure. Therefore, in the product testing of discrete semiconductor devices, leakage current testing is an indispensable link. Usually, the leakage current of the device under test (DUT) is at the nA or even pA level.

[0051] In the semiconductor testing process, in addition to the pin leakage current test, other parameters are often tested. In modern large-scale industrial production, in order to improve the test efficiency, a switch switching circuit is usually used to meet the circuit switching requirements of different parameter tests, and the corresponding DUT parameter test is performed under different working conditions of the switch. However, due to the parasitic effects of the switch itself, there is a leakage resistance between the coil and the contact, which is usually between 10GΩ and 10TΩ. The resulting switch leakage current is in the order of nA to pA level, such as Figure 1 The figure shows the equivalent resistance circuit diagram of the switch leakage current test circuit. The leakage resistance R1 of the switch is incorporated into the test circuit after the switch is closed. The current value actually measured by the test instrument is I m = t + 1 , where I t is the DUT leakage current, I 1 is the switch leakage current. Since the two have the same order of magnitude, the switch leakage current I 1 Will seriously affect the DUT leakage current I t The accuracy of the test and how to minimize or even eliminate the impact of are important issues that need to be solved when using switch switching circuits in semiconductor device testing.

[0052] In order to solve the above problems, the present application provides a test circuit, a test device and a test method, which will be described below through specific embodiments.

[0053] In one embodiment of the present application, please refer to Figure 1 , provides a test circuit, including a switch module 300, a measuring device 100 and a floating control circuit 200, wherein the switch module 300 is used to control the device under test to access the corresponding test circuit according to a switch action signal; the measuring device 100 is connected to the switch module 300, and is used to measure the leakage current of the device under test; the floating control circuit 200 is connected to both the switch module 300 and the measuring device 100, and is used to act according to the received test trigger signal, and provide a switch action signal to the coil of the switch module 300 to control the action of the switch module 300.

[0054] Specifically, the switch action signal includes a leakage current test action signal and other test action signals, and the corresponding test circuit includes a leakage current test circuit and other test circuits. The switch module 300 controls the device under test DUT to access the corresponding test circuit according to different switch action signals, thereby realizing efficient test switching. In some embodiments, the switch can be selected from one of a reed relay, an electromagnetic relay and a solid-state relay.

[0055] Furthermore, in some embodiments, the test device 100 is a nanoammeter or a picoammeter connected in series with a test power supply, which can be selected specifically according to the magnitude of the leakage current.

[0056] In the test circuit provided in the above embodiment, a floating control circuit is set to independently control the switch coil and separate it from the normal test circuit, which can minimize the impact of the switch on the test circuit. In addition, an isolated power supply with a voltage value much smaller than the test power supply is set in the floating control circuit to provide a working power supply for the switch coil, which can greatly reduce the voltage across the switch leakage resistance, and then greatly reduce the impact of the switch leakage current on the leakage current of the device to be tested. In addition, the test circuit can flexibly switch test circuits with different parameters by turning on and off the switch, thereby improving the test efficiency and meeting the needs of large-scale industrial production.

[0057] In one embodiment of the present application, please refer to Figure 2 , the switch module 300 includes:

[0058] The first switch 310 is configured as follows: the first contact is connected to the first power source V1 through the measuring device 100, the second contact is connected to the device under test DUT, and the first coil port and the second coil port are both connected to the floating control circuit 200;

[0059] Specifically, the first switch 310 is closed according to the leakage current test action signal to control the device under test DUT to access the leakage current test circuit, or is opened according to other test action signals to cut off the connection between the device under test DUT and the leakage current test circuit.

[0060] The second switch 320 is configured as follows: the first contact is connected to the second contact of the first switch 310, the second contact is connected to other test circuits, and the first coil port and the second coil port are both connected to the floating control circuit 200;

[0061] Specifically, the second switch 320 is opened according to the leakage current test action signal to cut off the connection between the device under test DUT and other test circuits, or is closed according to other test action signals to control the device under test DUT to access the test loop of other test circuits.

[0062] The third switch 330 is configured as follows: the first contact is connected to both the first power supply V1 and the floating control circuit 200 , the second contact is connected to the second contact of the second switch 320 , the first coil port is connected to the second power supply V2 , and the second coil port is connected to the floating control circuit 200 .

[0063] Specifically, the third switch 330 is closed according to the leakage current test action signal to short the first contact of the second switch 320 and the second contact of the second switch 320 , or is opened according to other test action signals.

[0064] In one embodiment of the present application, please continue to refer to Figure 2 , the floating control circuit 200 comprises:

[0065] The isolated power supply 210 is connected to the first power supply V1, the second power supply V2, the first switch 310, the second switch 320 and the third switch 330, and is used to provide a floating power supply for the first switch 310 and the second switch 320;

[0066] Specifically, the isolated power supply 210 is configured as follows: the second end is connected to the first coil port of the first switch 310, the first coil port of the second switch 320, the first contact of the third switch 330 and the first power supply V1, the third end is grounded, and the fourth end is connected to the second power supply V2.

[0067] The isolation driving circuit 220 is connected to the first power source V1, the first switch 310, the second switch 320, the third switch 330 and the isolation power source 210, and is used to provide an action signal to the coil of the first switch 310 and the coil of the second switch 320 after being actuated, so as to actuate the first switch 310 and the second switch 320;

[0068] Specifically, the isolation driving circuit 220 is configured as follows: a first end is connected to the first end of the isolation power supply 210 , a second end is connected to the second coil port of the second switch 320 , and a third end is connected to the second coil port of the first switch 310 .

[0069] The switch control circuit 230 is connected to both the isolation driving circuit 220 and the third switch 330 , and is used to generate a control signal according to the test trigger signal to control the isolation driving circuit 220 to generate an action signal, or to control the third switch 330 to act.

[0070] Specifically, the switch control circuit 230 is configured as follows: the first end is connected to the second coil port of the third switch 330, the second end is connected to the sixth end of the isolation drive circuit 220, the third end is connected to the fifth end of the isolation drive circuit 220, the fourth end is connected to the fourth end of the isolation drive circuit 220, and the fifth end is grounded.

[0071] Furthermore, the tester sends a test trigger signal to the switch control circuit 230 according to the test requirements. The switch control circuit 230 determines what kind of test to perform according to the test trigger signal, and then generates a corresponding control signal, and sends corresponding action signals to the third switch 330 and the isolation drive circuit 220 respectively, thereby controlling the switch inside the switch module 300 to complete the corresponding opening and closing action, so as to control the device under test DUT to access the corresponding test circuit.

[0072] In one embodiment of the present application, please refer to Figure 3 , the circuit works in the leakage current test state, wherein the resistor R1 is the equivalent leakage resistance between the coil and the contact of the first switch 310, the resistor R2 is the equivalent leakage resistance between the coil and the contact of the second switch 320, and R3 is the equivalent leakage resistance between the contacts of the second switch 320. At this time, the switch control circuit 230 controls the isolation drive circuit 220 to turn on the first switch 310 and turn off the second switch 320, and at the same time controls the third switch 330 to turn on, so that the device under test DUT is connected to the leakage current test loop and isolated from other test circuits through the second switch 320.

[0073] Specifically, due to the existence of the equivalent leakage resistors R1, R2, and R3, when the measuring device 100 measures the leakage current of the device under test DUT, the leakage current passing through the equivalent leakage resistors R1, R2, and R3 will also be counted into the measuring device 100, resulting in a huge error in measuring the leakage current of the DUT, that is, I m =I t +I 1 +I 2 +I 3 , where I 1 is the leakage current of the equivalent leakage resistor R1, I 2 is the leakage current of the equivalent leakage resistance R2, I 3 How to reduce I 1 +I 2 +I 3 The value of is related to the accuracy of the final leakage current measurement result. Figure 3 As can be seen from the circuit structure, since the measuring device 100 is a nanoammeter or a picoammeter, the internal resistance is negligible, so the voltage value across the equivalent leakage resistor R1 is V1, and the voltage difference ΔU 1 =0V, so I 1 =0A, similarly, I 2 =0A, I 3 =0A, it can be seen that after the floating control circuit 200 provides a floating power supply for the switch module 300, the leakage current generated at the switch end can be made 0, and the indication read by the measuring device 100 only includes the leakage current flowing through the device under test DUT. Therefore, the current value measured by the measuring device 100 can accurately reflect the actual leakage current of the DUT.

[0074] In one embodiment of the present application, please refer to Figure 4 , the circuit works in other test states, the switch control circuit 230 controls the isolation drive circuit 220 to disconnect the first switch 310 and turn on the second switch 320, and at the same time controls the third switch 330 to disconnect, so that the device under test DUT is connected to other test circuits and isolated from the leakage current test circuit through the first switch 310 and the third switch 330.

[0075] In one embodiment of the present application, please refer to Figure 5 , a structural principle diagram of a floating control circuit provided by the present invention, the isolation drive circuit 220 is two photoelectric couplers, the switch control circuit 230 includes: a first controllable switch unit K1, a second controllable switch unit K2, a third controllable switch unit K3 and a current limiting resistor R, wherein the first controllable switch unit K1 is configured as: a first pole is connected to the fourth end of the isolation drive circuit 220, and a second pole is grounded; the second controllable switch unit K2 is configured as: a first pole is connected to the fifth end of the isolation drive circuit 220, and a second pole is grounded; the third controllable switch unit K3 is configured as: a first pole is connected to the second coil port of the third switch 330, and a second pole is grounded; the current limiting resistor R is connected in series between the third power supply V3 and the sixth end of the isolation drive circuit 220.

[0076] Specifically, the photoelectric coupler is a commonly used photoelectric isolation device, which contains a light-emitting diode. When the photoelectric coupler is working, the light-emitting diode is first turned on and emits light of a fixed wavelength, which is received by the photodetector to generate photocurrent, and then output after further amplification. It is often used in situations where signal isolation is required. In this embodiment, the tester sends a test trigger signal to the switch control circuit 230 through the control center to control the first controllable switch unit K1, the second controllable switch unit K2 and the third controllable switch unit K3 to work normally, thereby controlling the isolation drive circuit 220 and the third switch 330 to work normally. Voltage isolation is performed through the photoelectric coupler in the isolation drive circuit 220, so that the coil drive voltages of the first switch 310 and the second switch 320 float to the first power supply V1 without interference.

[0077] In one embodiment of the present application, Figure 6 As shown, the present invention further provides a test circuit including an equipotential circuit unit 400, and the equipotential circuit unit 400 is used to shield the leakage current of the test circuit to the outside. In this embodiment, the equipotential circuit unit can adopt a guard protection circuit.

[0078] Specifically, electrostatic discharge (ESD) is usually generated by contact, friction, induction between electrical appliances, etc., and is characterized by long-term accumulation, high voltage (can generate several thousand volts or even tens of thousands of volts of static electricity), low power, small current and short action time. For electronic products, if the ESD design is not well designed, it often causes unstable operation or even damage of electronic and electrical products. In this regard, guard protection circuits can be used in circuit design to prevent the circuit from discharging to the ground through parasitic devices due to static electricity accumulation, which can cause a series of problems.

[0079] Furthermore, the guard protection circuit is led out from the low impedance end of the measuring device near the first power supply to form a low impedance ground connection, which can reduce the influence of the impedance of other power circuits through the PCB on the leakage current test circuit, and shield the influence of space electromagnetic radiation on the leakage current test circuit. In this embodiment, the lead wire of the guard protection circuit 400 is led out from the low impedance end of the measuring device 100 near the first power supply V1 to form a low impedance ground connection, thereby reducing the influence of the impedance of other test circuits through the PCB on the leakage current test circuit, and shielding the influence of space electromagnetic radiation on the leakage current test circuit.

[0080] In one embodiment of the present application, Figure 7 As shown, the present invention provides a test circuit structure schematic diagram of a three-pin semiconductor discrete device. Compared with a two-pin semiconductor discrete device, the test circuit from the first pin to the common pin is the same as the test circuit from the second pin to the common pin, and can be symmetrically arranged. On the one hand, the leakage current of the common pin to the ground is eliminated by setting a seventh switch to be directly short-circuited with the ground. On the other hand, by setting a guard protection circuit, the parasitic leakage current at the common pin end is discharged to the ground, so that the leakage current at the common pin end does not affect the leakage current test of the first pin and the second pin to the common pin.

[0081] In one embodiment of the present application, Figure 8 As shown, the present invention provides a testing method, comprising:

[0082] Step 22, generating the leakage current test action signal according to the leakage current test trigger signal, controlling the first switch and the third switch to be closed, and controlling the second switch to be opened, so as to control the test circuit to enter the leakage current test working state;

[0083] Step 24, generating the other test action signal according to the other test trigger signal, controlling the first switch and the third switch to be opened, and controlling the second switch to be closed, so as to control the test circuit to enter other test working states.

[0084] It should be noted that in the embodiments provided in the present application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the system embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0085] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0086] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated units may be implemented in the form of hardware.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A test circuit, characterized in that: include: A switch module, used to control the device under test to access the corresponding test circuit according to the switch action signal; A measuring device, connected to the switch module, for measuring the leakage current of the device under test; A floating control circuit, connected to the switch module and the measuring device, for acting according to a received test trigger signal and providing the switch action signal to the switch module to control the action of the switch module; Wherein, the switch action signal includes a leakage current test action signal and other test action signals; the switch module includes: A first switch is configured such that: a first contact is connected to a first power source through the measuring device, a second contact is connected to the device under test, and a first coil port and a second coil port are both connected to the floating control circuit; The first switch is further configured to: close according to the leakage current test action signal to control the device under test to access the leakage current test circuit, or open according to the other test action signal to cut off the connection between the device under test and the leakage current test circuit; A second switch is configured such that: a first contact is connected to a second contact of the first switch, a second contact is connected to other test circuits, and a first coil port and a second coil port are both connected to the floating control circuit; The second switch is further configured to: be opened according to the leakage current test action signal to cut off the connection between the device under test and the other test circuit, or be closed according to the other test action signal to control the device under test to access the test loop of the other test circuit; a third switch, configured as follows: a first contact connected to both the first power supply and the floating control circuit, a second contact connected to the second contact of the second switch, a first coil port connected to the second power supply, and a second coil port connected to the floating control circuit; The third switch is further configured to be closed according to the leakage current test action signal to short-circuit the first contact of the second switch and the second contact of the second switch, or to be opened according to the other test action signal.

2. The circuit according to claim 1, characterized in that The floating control circuit comprises: an isolated power supply, connected to the first power supply, the second power supply, the first switch, the second switch and the third switch, and used to provide a floating power supply for the first switch and the second switch; an isolation driving circuit, connected to the first power supply, the first switch, the second switch, the third switch and the isolation power supply, and used for providing the action signal to the coil of the first switch and the coil of the second switch after being actuated, so as to actuate the first switch and the second switch; The switch control circuit is connected to both the isolation drive circuit and the third switch, and is used to generate a control signal according to the test trigger signal to control the action of the isolation drive circuit to generate the action signal, or to control the action of the third switch.

3. The circuit according to claim 2, characterized in that The isolated power supply is configured as: The first end is connected to the isolation drive circuit, the second end is connected to the first coil port of the first switch, the first coil port of the second switch, the first contact of the third switch and the first power supply, the third end is grounded, and the fourth end is connected to the second power supply.

4. The circuit according to claim 3, characterized in that The isolation driving circuit is configured as follows: The first end is connected to the first end of the isolated power supply, the second end is connected to the second coil port of the second switch, the third end is connected to the second coil port of the first switch, and the fourth end, the fifth end and the sixth end are all connected to the switch control circuit.

5. The circuit according to claim 4, characterized in that The switch control circuit is configured as follows: The first end is connected to the second coil port of the third switch, the second end is connected to the sixth end of the isolation drive circuit, the third end is connected to the fifth end of the isolation drive circuit, the fourth end is connected to the fourth end of the isolation drive circuit, and the fifth end is grounded.

6. The circuit according to claim 5, characterized in that The switch control circuit includes a first controllable switch unit, a second controllable switch unit, a third controllable switch unit and a current limiting resistor; The first controllable switch unit is configured as follows: a first pole is connected to the fourth end of the isolation drive circuit, and a second pole is grounded; The second controllable switch unit is configured as follows: a first pole is connected to the fifth terminal of the isolation drive circuit, and a second pole is grounded; The third controllable switch unit is configured as follows: a first pole is connected to the second coil port of the third switch, and a second pole is grounded; The current limiting resistor is connected in series between the third power supply and the sixth terminal of the isolation driving circuit.

7. The circuit according to any one of claims 1 to 6, characterized in that: Also includes: The equipotential circuit unit is used to shield the external leakage current of the test circuit.

8. A testing device, characterized in that: include: A circuit as claimed in any one of claims 1 to 7.

9. A testing method, characterized in that: The method is applied to the circuit according to any one of claims 1 to 7; the method comprises: Generate the leakage current test action signal according to the leakage current test trigger signal, control the first switch and the third switch to be closed, and control the second switch to be opened, so as to control the test circuit to enter the leakage current test working state; The other test action signal is generated according to other test trigger signals, the first switch and the third switch are controlled to be opened, and the second switch is controlled to be closed, so as to control the test circuit to enter other test working states.

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