JP6197573B2 - Switching element inspection method and electronic circuit unit - Google Patents

Description

  The present invention relates to a switching element inspection method and an electronic circuit unit, and more particularly to a switching element inspection method for an electronic circuit unit including switching elements connected in parallel.

  A power switch is provided between the load circuit and the power source to control power supply to the load. In recent years, with the increase in power consumption of the load circuit, this power switch is also required to have a high current supply capability. Therefore, as one means for improving the current supply capability of the power switch, switching elements are connected in parallel.

  In addition, for electronic circuit units having such switching elements connected in parallel, it is possible to perform a test to ensure that the switching elements mounted on the electronic circuit unit function correctly, as with other electronic circuit units. Is required. Therefore, Patent Document 1 discloses a method for testing circuit elements connected in parallel.

  In Patent Document 1, a plurality of inverters connected in parallel is provided, and a plurality of transistors are individually tested by generating a signal for individually controlling the plurality of transistors constituting the plurality of inverters.

JP 2012-208037 A

  However, a plurality of switching elements connected in parallel to improve the current supply capability are usually controlled collectively. Therefore, as in the technique described in Patent Document 1, it is possible to provide a circuit that generates a signal state different from a normal state such as a decoder in order to individually test a plurality of switching elements connected in parallel. This is a problem because it causes an increase in circuit area or an increase in circuit mounting area.

  The present invention has been made in view of the above circumstances, and individually inspects switching elements in an electronic circuit unit having a plurality of switching elements connected in parallel while reducing the number of circuits added for testing. The purpose is to improve reliability.

  One aspect of the switching element inspection method according to the present invention is a switching element inspection method for inspecting an electronic circuit unit including a plurality of switching elements connected in parallel, wherein the first terminal and the second terminal of the switching element A test signal input terminal for providing a test signal to a control terminal of one test target switching element selected from the plurality of switching elements; A step of installing, a step of applying a first test voltage larger than a threshold voltage of the inspection target switching element as the inspection signal, the first inspection terminal, and the second inspection terminal. Checking the voltage difference between.

  In one aspect of the electronic circuit unit according to the present invention, a plurality of switching elements connected in parallel between a power supply terminal and an output terminal, and a control signal for controlling the plurality of switching elements are supplied to the plurality of switching elements. Test voltage generation comprising: a control signal generation circuit that collectively applies; and a plurality of test pads that are provided between the control signal generation circuit and the plurality of switching elements and apply a voltage to a control terminal for each of the plurality of switching elements The test voltage generation circuit includes a second test voltage that is lower than a threshold voltage of the plurality of switching elements, based on a first test voltage applied to a test pad corresponding to the test target switching element. A test voltage is generated, and the second test voltage is applied to a non-test target switching element other than the test target switching element. Give.

  According to the present invention, the reliability of an electronic circuit unit having a plurality of switching elements connected in parallel can be improved.

1 is a block diagram of an electronic circuit unit according to a first embodiment. 3 is a flowchart for explaining a switching element inspection method according to the first exemplary embodiment; FIG. 3 is a block diagram of an electronic circuit unit serving as a comparative example of the electronic circuit unit according to the first embodiment. It is a block diagram of the electronic circuit unit concerning Embodiment 2. FIG. 5 is a flowchart for explaining a switching element inspection method according to a second exemplary embodiment;

  Embodiments of the present invention will be described below with reference to the drawings. First, an electronic circuit unit to be inspected in the switching element inspection method according to the present invention will be described. FIG. 1 is a block diagram of the electronic circuit unit 1 according to the first embodiment. In this electronic circuit unit, for example, a switching element, a control circuit for controlling the switching element (for example, a gate drive circuit), and other associated circuit elements are mounted on a PCB (Printed Circuit Board) substrate. . The electronic circuit unit is separately supplied with power supplied to the switching element and power supplied to other circuit elements such as a control circuit. Note that power supply to elements other than the switching element such as a control circuit may be performed using a power supply circuit mounted on the PCB substrate from the power supplied to the switching element. In the following description, the description of the power supply path for circuit elements other than the switching elements is omitted.

  As shown in FIG. 1, the electronic circuit unit 1 according to the first embodiment includes a control circuit (for example, gate drive circuit 10), switching elements (for example, switching transistors M1 and M2), a power supply terminal VCC, and an output terminal OUT. , A drain pad PADd, a source pad PADs, and test pads PAD1, PAD2.

  The gate drive circuit 10 collectively applies control signals for controlling a plurality of switching elements (for example, switching transistors M1 and M2) to the switching transistors M1 and M2. The gate drive circuit 10 includes a gate control signal generation circuit 11 and a test voltage generation circuit 12. In the gate drive circuit 10, the gate control signal generation circuit 11 generates a control signal to be collectively applied to the control terminals (for example, gate terminals) of the switching transistors M 1 and M 2. In the gate drive circuit 10, the voltage of the control signal generated by the gate control signal generation circuit 11 is converted into a voltage suitable for controlling the switching transistors M 1 and M 2 using the test voltage generation circuit 12.

  As described above, the test voltage generation circuit 12 converts the voltage of the control signal into a voltage suitable for controlling the switching transistors M1 and M2 in the normal operation. However, in the first embodiment, the test voltage generation circuit 12 generates a voltage to be applied to the gates of the switching transistors M1 and M2 from a test signal applied to the test pads PAD1 and PAD2 provided in the gate drive circuit 10 during the test. Therefore, for the sake of explanation, it is referred to as a test voltage generation circuit. That is, the test voltage generation circuit 12 is used in the normal operation in the gate drive circuit 10 and is not newly provided for the test. Details of the test voltage generation circuit 12 will be described later.

  The gate control signal generation circuit 11 outputs, for example, a voltage obtained by boosting the power supply voltage VCC as a control signal that turns on the switching transistors M1 and M2. Further, the gate control signal generation circuit 11 switches whether the control signal is set to a high level (for example, a boosted voltage) or a low level based on an instruction from another circuit (not shown).

  The switching transistors M1 and M2 are connected in parallel between the power supply terminal to which the power supply voltage VCC is applied and the output terminal OUT. The control signals (for example, gates) of the switching transistors M1 and M2 are given control signals having the same logic level from the gate control signal generation circuit 11 in the normal use mode. In addition, voltages of different logic levels are applied to the gates of the switching transistors M1 and M2 in the test mode. Details of the operation in the test mode will be described later.

  A load resistor RL that simulates a load circuit is connected between the output terminal OUT of the electronic circuit unit 1 according to the first embodiment and a ground terminal to which the ground voltage GND is applied. In the electronic circuit unit 1, the drain pad PADd is provided at the first terminals (for example, drain terminals) of the switching transistors M1 and M2. In the electronic circuit unit 1, source pads PADs are provided at second terminals (for example, source terminals) of the switching transistors M1 and M2.

  Next, details of the test voltage generation circuit will be described. Here, the configuration of the test voltage generation circuit 12 especially assuming a test time will be described. The test voltage generation circuit 12 is provided between the gate control signal generation circuit 11 and the switching transistors M1 and M2, and generates a second test voltage from the first test voltage. In addition, the test voltage generation circuit 12 includes a plurality of test pads that apply a voltage to the gate of the switching element for each of the plurality of switching elements. The test voltage generation circuit 12 switches off the non-inspection switching transistors other than the inspection target switching transistor to which the first test voltage is applied to the gate by the second test voltage.

  The test voltage generation circuit 12 includes, for each switching element, a first resistor inserted on a wiring connecting the gate control signal generation circuit 11 and the gate of the switching transistor, and the first resistor and the gate of the switching transistor. And a second resistor provided between the wiring connecting the two and the ground terminal. In the example shown in FIG. 1, the resistor R11 is a first resistor provided corresponding to the switching transistor M1, and the resistor R12 is a second resistor provided corresponding to the switching transistor M1. The resistor R21 is a first resistor provided corresponding to the switching transistor M2, and the resistor R22 is a second resistor provided corresponding to the switching transistor M2.

  More specifically, the resistor R11 is provided between the gate control signal generation circuit 11 and the gate of the switching transistor M1. The resistor R12 is provided between a wiring connecting the resistor R11 and the gate of the switching transistor M1 and a ground terminal. In the test voltage generation circuit 12, a test pad PAD1 is provided on the wiring connecting the resistor R11 and the gate of the switching transistor M1. The resistor R21 is provided between the gate control signal generation circuit 11 and the gate of the switching transistor M2. The resistor R22 is provided between a wiring connecting the resistor R21 and the gate of the switching transistor M2 and the ground terminal. In the test voltage generation circuit 12, the test pad PAD2 is provided on the wiring connecting the resistor R21 and the gate of the switching transistor M2. In other words, the test voltage generation circuit 12 applies the test voltage to the wiring connecting the first resistor and the gate of the switching transistor. The test voltage is output from an inspection device (not shown).

  Here, the relationship between the first test voltage applied to the test voltage generation circuit 12 and the second test voltage generated by the test voltage generation circuit 12 will be described. This first test voltage is given as an inspection signal from an inspection device (not shown) in the test mode of the electronic circuit unit 1.

  In the switching element inspection method according to the first embodiment, when the electronic circuit unit 1 is set to the test mode, the output of the gate control signal generation circuit 11 is cut off. Then, the first test voltage is applied from the inspection apparatus to the test pad connected to the gate of the inspection target switching transistor to be tested, and the test voltage generation circuit 12 generates the second test voltage. As a result, the inspection target switching transistor becomes conductive, and the non-inspection switching transistors other than the inspection target switching transistor are cut off.

The relationship between the first test voltage and the second test voltage is expressed by the equation (1) when the switching transistor M1 is an inspection target. In the equation (1), Vg1 is a first test voltage and is applied to the test pad PAD1. Vg2 is a second test voltage, which is applied to the gate of the switching transistor M2. Vth2 is a threshold voltage of the switching transistor M2, which is a non-inspected switching transistor. R11, R21, and R22 are resistance values of the resistors R11, R21, and R22, respectively.

  If the relationship between the first resistance and the second resistance does not satisfy the above expression (1), the ground voltage GND may be applied to the gate of the non-inspected switching transistor as the second test voltage.

  Subsequently, the switching element inspection method according to the first embodiment will be described in detail. FIG. 2 is a flowchart showing the procedure of the switching element inspection method according to the first embodiment.

  As shown in FIG. 2, in the switching element inspection method according to the first embodiment, first, the first inspection terminal and the second inspection terminal of the inspection apparatus are provided on the drain pad PADd and the source pad PADs of the electronic circuit unit 1. In addition to the installation, control signal input terminals are installed on the test pads PAD1 and PAD2 (step S1). In the following description, the first inspection terminal, the second inspection terminal, and the inspection signal input terminal are referred to as probe pins.

  Subsequently, in the switching element inspection method according to the first embodiment, the power supply voltage VCC is applied to the switching transistors M1 and M2 (step S2). In this step S2, since no voltage is applied to the test pads PAD1, PAD2, and the gate control signal generation circuit 11 is off or the output is cut off, the drain pad PADd becomes the power supply voltage VCC, and the source The pad PADs becomes the ground voltage GND.

  Subsequently, in the switching element inspection method according to the first embodiment, the first test voltage Vg1 is applied as the inspection signal to the test pad PAD1, and the first test voltage Vg1 is applied to the gate of the switching transistor M1 to be inspected. At the same time, a second test voltage Vg2 to be applied to the gate of the switching transistor M2 to be tested is generated (step S3). The first test voltage Vg1 is a voltage sufficient to bring the switching transistor M1 to be inspected into a conductive state. Further, the second test voltage Vg2 is a voltage calculated by the equation (1), and is a voltage sufficient to put the switching transistor M2 in the cutoff state.

  Subsequently, in the switching element inspection method according to the first embodiment, the voltage of the drain pad PADd and the voltage of the source pad PADs are measured, and the voltage between the drain and source of the switching transistor M1 to be inspected is higher than the specified voltage Vpass. It is determined whether it is small (step S4). When it is determined that the drain-source voltage is greater than the specified voltage Vpass, it is determined that there is a problem in the mounting state or element characteristics of the switching transistor M1, and the measurement is terminated. On the other hand, when it is determined that the drain-source voltage is equal to or lower than the specified voltage Vpass, it is determined that the mounting state or element characteristics of the switching transistor M1 are correct, and the measurement of the switching transistor M1 is terminated.

  Subsequently, in the switching element inspection method according to the first exemplary embodiment, the first test voltage Vg1 is applied to the test pad PAD2, the first test voltage Vg1 is applied to the gate of the switching transistor M2 to be inspected, and A second test voltage Vg2 to be applied to the gate of the non-inspected switching transistor M1 is generated (step S5). The first test voltage Vg1 is a voltage sufficient to bring the switching transistor M2 to be inspected into a conductive state. Further, the second test voltage Vg2 is a voltage calculated by the equation (1), and is a voltage sufficient to put the switching transistor M1 in the cutoff state.

  Subsequently, in the switching element inspection method according to the first exemplary embodiment, the voltage of the drain pad PADd and the voltage of the source pad PADs are measured, and the drain-source voltage of the switching transistor M2 to be inspected is higher than the specified voltage Vpass. It is determined whether it is small (step S6). If it is determined that the drain-source voltage is greater than the specified voltage Vpass, it is determined that there is a problem in the mounting state or element characteristics of the switching transistor M2, and the measurement is terminated. On the other hand, when it is determined that the drain-source voltage is equal to or lower than the specified voltage Vpass, it is determined that the mounting state or element characteristic of the switching transistor M2 is correct, and the measurement is terminated.

  Subsequently, in the switching element inspection method according to the first exemplary embodiment, the measurement is finished by removing the probe pad of the inspection device from the test pad of the electronic circuit unit 1 (step S7).

  Note that the specified voltage Vpass in the flowchart is set based on the product of the ON resistance of the switching transistor and the output current value assumed as the current flowing through the load resistor RL.

  From the above description, according to the switching element inspection method and the electronic circuit unit according to the first embodiment, the plurality of switching transistors are individually turned on by the test pads that individually apply voltages to the gates of the switching transistors connected in parallel. It can be. In the switching element inspection method according to the first embodiment, the test voltage generation circuit 12 uses the first test voltage that turns on the switching transistor to be inspected to turn off the non-inspection switching transistor from the first test voltage. A test voltage can be generated. Therefore, by using the switching element inspection method and the electronic circuit unit 1 according to the first embodiment, the inspection device that performs only one voltage output and two voltage observations is collectively controlled by one control signal, and A plurality of switching transistors connected in parallel can be individually inspected.

  In addition, according to the switching element inspection method and the electronic circuit unit 1 according to the first embodiment, the test voltage generation circuit 12 is a circuit normally used in the gate drive circuit 10, and a separate circuit is provided to realize the above operation. There is no need to add.

  Here, in order to further explain the above-described effect, a plurality of switching transistors that are collectively controlled by one control signal and connected in parallel by an inspection apparatus that performs only one voltage output and two voltage observations are provided. FIG. 3 shows a block diagram of the electronic circuit unit 100 when individually inspecting. In the example shown in FIG. 3, a test pad PADg is provided at the output of the gate control signal generation circuit 11 in order to make two switching transistors conductive by applying one voltage. The electronic circuit unit 100 shown in FIG. 3 can test both the switching transistors M1 and M2 by applying a test voltage to the test pad PADg. However, in the electronic circuit unit 100, the drain-source voltage that can be determined to be normal is measured by a normal switching transistor even if there is a malfunction of one of the switching transistors M1 and M2. Judgment may occur.

  However, in the switching element inspection method and the electronic circuit unit 1 according to the first embodiment, since the switching transistors can be individually tested, the above erroneous determination does not occur. Moreover, the switching element inspection method and the electronic circuit unit 1 according to the first embodiment can improve the reliability of the electronic circuit unit 1 by preventing erroneous determination of the switching transistor.

  In the above description, it is assumed that the gate control signal generation circuit 11 is in the off state or the output is cut off during the inspection process. However, the output of the gate control signal generation circuit 11 may be set to a low level during the inspection process. When the output of the gate control signal generation circuit 11 is set to the low level during the inspection process, the non-inspected switching transistor can be cut off regardless of the resistance values of the first resistor and the second resistor. In this case, the second resistor of the gate control signal generation circuit 11 can be eliminated.

  In the electronic circuit unit 1 according to the first embodiment, the test voltage generation circuit 12 has the first resistance and the second resistance, so that the gate control signal generation circuit 11 is not provided, or the gate This is advantageous in that the inspection can be performed in a state in which the control signal generation circuit 11 is surely in a state that does not affect the measurement.

Embodiment 2
In the second embodiment, a switching element inspection method when the number of parallel switching transistors of the electronic circuit unit 1 according to the first embodiment is further increased will be described. FIG. 4 shows a block diagram of the electronic circuit unit 2 according to the second embodiment. In the description of the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted.

  As shown in FIG. 4, in the electronic circuit unit 2 according to the second embodiment, n switching transistors are connected in parallel. In addition, the electronic circuit unit 2 includes a first resistor (resistors R11 to Rn1 in FIG. 4) and a second resistor (resistors R12 to Rn2 in FIG. 4) on wirings that transmit control signals to n switching transistors, respectively. ). The first resistor is provided in series with the wiring that transmits the control signal, and the second resistor is provided between the wiring that transmits the control signal and the ground terminal. In FIG. 4, the test voltage generation circuit 21 is shown as a circuit having resistors R11 to Rn1 and resistors 12 to Rn2. In addition, the gate drive circuit having the test voltage generation circuit 21 instead of the test voltage generation circuit 11 is denoted by 20.

  The test voltage generation circuit 21 includes a plurality of test pads PAD1 to PADn corresponding to each of the n switching transistors. A first test voltage that turns on the switching transistor is applied to the test pad corresponding to the switching transistor selected as the inspection target among the test pads PAD1 to PADn.

  Subsequently, a procedure of the switching element inspection method according to the second embodiment will be described. FIG. 5 is a flowchart showing the procedure of the switching element inspection method according to the second embodiment.

  As shown in FIG. 5, in the switching element inspection method according to the second embodiment, first, test pins (for example, drain pad PADd, source pad PADs, test pads PAD1 to PADn) of the electronic circuit unit 1 are connected to probe pins of the inspection apparatus. Are connected (step S11).

  Subsequently, in the switching element inspection method according to the second embodiment, the power supply voltage VCC is applied to the switching transistors M1 to Mn (step S12). In step S12, since no voltage is applied to the test pads PAD1 to PADn and the gate control signal generation circuit 11 is off or the output is cut off, the drain pad PADd becomes the power supply voltage VCC. The pad PADs becomes the ground voltage GND.

  Subsequently, in the switching element inspection method according to the second embodiment, when the number of the switching transistor to be inspected is i, the inspection device sets the switching transistor to be selected first (that is, i = 1). (Step S13). Thereafter, the first test voltage Vg1 is applied to the test pad PADi, the first test voltage Vg1 is applied to the gate of the switching transistor Mi to be tested, and the first test voltage Vg1 is applied to the gate of the non-testing switching transistor Mj. 2 test voltage Vg2 is generated (step S14). J represents a number other than i, and when there are n switching transistors, it represents an integer of 1 to n other than i. Further, the first test voltage Vg1 is a voltage sufficient to bring the switching transistor Mi to be inspected into a conductive state. Further, the second test voltage Vg2 is a voltage calculated by the equation (1), and is a voltage sufficient to put the switching transistor Mj in a cut-off state.

  Subsequently, in the switching element inspection method according to the second embodiment, the voltage of the drain pad PADd and the voltage of the source pad PADs are measured, and the drain-source voltage of the switching transistor Mi to be inspected is higher than the specified voltage Vpass. It is determined whether it is small (step S15). When it is determined that the drain-source voltage is greater than the specified voltage Vpass, it is determined that there is a problem in the mounting state or element characteristics of the switching transistor Mi, and the measurement ends. On the other hand, when it is determined that the drain-source voltage is equal to or lower than the specified voltage Vpass, it is determined that the mounting state or element characteristic of the switching transistor Mi is correct.

  Subsequently, in the switching element inspection method according to the second embodiment, it is determined whether i indicating the number of the switching transistor to be inspected is a value greater than or equal to n (step S16). Is incremented by 1 (step S17), and the processes of steps S14 to S15 are repeated. On the other hand, if it is determined in step S16 that i indicating the number of the switching transistor to be inspected is a value equal to or greater than n, the measurement is ended by removing the probe pad of the inspection device from the test pad of the electronic circuit unit 2 (step S16). S18).

  From the above description, the switching element inspection method and the electronic circuit unit 2 according to the second embodiment also include the test voltage generation circuit 21 so that a plurality of control devices that are collectively controlled by one control signal and connected in parallel are provided. The switching transistors can be individually tested. Moreover, the reliability of the electronic circuit unit 2 can also be improved in the switching element inspection method and the electronic circuit unit 2 according to the second embodiment. Also in the second embodiment, a circuit to be newly added is not necessary for generating the second test voltage Vg2.

  In the above description, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the embodiments already described, and various modifications can be made without departing from the scope of the invention. It goes without saying that changes are possible. For example, in the above-described embodiment, an example in which a MOS (Metal Oxide Semiconductor) transistor is employed as the switching element has been described. However, a bipolar transistor can be used as the switching element. In this case, the first terminal corresponds to the collector terminal of the bipolar transistor, the second terminal corresponds to the emitter terminal of the bipolar transistor, and the control terminal serves as the base terminal of the bipolar transistor.

1, 2 Electronic circuit unit 10, 20 Gate drive circuit 11 Gate control signal generation circuit 12, 21 Test voltage generation circuit PADd Drain pad PADs Source pad PAD1, PAD2, PADm, PADn Test pad

Claims (10)

A switching element inspection method for inspecting an electronic circuit unit including a plurality of switching elements connected in parallel,
The electronic circuit unit is:
A control signal generation circuit that collectively gives control signals for controlling the plurality of switching elements to the plurality of switching elements;
Provided between the control signal generation circuit and the plurality of switching elements, from a first test voltage larger than a threshold voltage of the inspection target switching element to a control terminal of a non-inspection target switching element other than the inspection target switching element A test voltage generation circuit for generating a second test voltage to be applied,
The test voltage generation circuit, for each switching element,
A first resistor inserted on a wiring connecting the control signal generation circuit and a control terminal of the switching element;
A second resistor provided between a wiring connecting the first resistor and a control terminal of the switching element and a ground terminal;
The first test voltage is applied to a wiring connecting the first resistor and a control terminal of the switching element;
Installing a first inspection terminal and a second inspection terminal on the first terminal and the second terminal of the switching element, respectively;
Installing an inspection signal input terminal for supplying an inspection signal to a control terminal of one inspection target switching element selected from the plurality of switching elements;
Applying the first test voltage as the inspection signal;
Inspecting a voltage difference between the first inspection terminal and the second inspection terminal;
A switching element inspection method comprising:   The switching element inspection method according to claim 1, wherein the first test voltage is applied while switching the inspection target switching element. The second test voltage is:
The first resistor connected to the control terminal of the inspection target switching element, the first resistor and the second resistance connected to the control terminal of a non-inspection switching element other than the inspection target switching element, , The product of the first test voltage and the resistance ratio of the first combined resistance calculated from the above, the second resistance connected to the control terminal of the non-test target switching element, and The switching element inspection method according to claim 1 , wherein the switching element inspection method is set to be smaller than a threshold voltage of a non-inspection target switching element. The test voltage generation circuit includes:
Wherein the first resistor provided in a wiring connecting the control terminal of the switching element, the switching element inspecting method according to claim 1, the test pad of the first test voltage is applied is provided. It said test voltage generating circuit includes a switching element inspecting method according to any one of claims 1 to 4 in the gate drive circuit including the control signal generating circuit provided in the output of the gate drive circuit. The period for applying the first test voltage to the control terminal of said object switching element, any one of claims 1 to 5 for applying a ground voltage to the control terminal of the non-inspected switching element other than the inspected switching element 2. The switching element inspection method according to item 1. A plurality of switching elements connected in parallel between the power supply terminal and the output terminal;
A control signal generation circuit that collectively gives control signals for controlling the plurality of switching elements to the plurality of switching elements;
A test voltage generation circuit including a plurality of test pads provided between the control signal generation circuit and the plurality of switching elements and applying a voltage to a control terminal for each of the plurality of switching elements;
The test voltage generation circuit includes:
Generating a second test voltage smaller than a threshold voltage of the plurality of switching elements from a first test voltage applied to a test pad corresponding to the switching element to be tested;
An electronic circuit unit that applies the second test voltage to a non-inspection switching element other than the inspection object switching element. The test voltage generation circuit is provided for each of the plurality of switching elements.
A first resistor inserted on a wiring connecting the control signal generation circuit and a control terminal of the switching element;
A second resistor provided between a wiring connecting the first resistor and a control terminal of the switching element and a ground terminal;
The electronic circuit unit according to claim 7 , wherein the test pad is provided on a wiring connecting the first resistor and a control terminal of the switching element. The resistance values of the first resistor and the second resistor are:
A product of a combined resistance calculated from the first resistance and the second resistance and the first test voltage is set to be smaller than a threshold voltage of the non-test target switching element;
The combined resistance includes a first resistance value connected to a control terminal of the inspection target switching element, the first resistance connected to a control terminal of a non-inspection switching element other than the inspection target switching element, and the The electronic circuit unit according to claim 8 , wherein the electronic circuit unit is calculated by a resistance ratio between a total resistance obtained by summing up the second resistances and the second resistance connected to a control terminal of the non-test target switching element. It said test voltage generating circuit, the electronic circuit unit according to any one of claims 7 to 9 provided at the output of the gate drive circuit in the gate drive circuit including the control signal generating circuit.

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