Desat protection circuit with switchable protection time and method of testing a device

Abstract

The application relates to the field of semiconductor devices, and discloses a Desat protection circuit with switchable protection time and a testing method of a device, wherein the Desat protection circuit with switchable protection time comprises a driving unit for turning on or turning off a power semiconductor device to be tested, a time switching unit for switching a preset protection time, and a state monitoring unit for monitoring a voltage across the power semiconductor device to be tested, so that when a short circuit test is performed on the power semiconductor device to be tested, that is, when the voltage across the power semiconductor device to be tested is greater than a preset threshold voltage, a signal for turning off the power semiconductor device to be tested is sent to the driving unit after the preset protection time. The application connects the time adjusting circuit corresponding to the adjusting switch to the state monitoring unit by closing the adjusting switch, so that the preset protection time is switched, different power semiconductor device testing requirements are met, and one driving board covers the testing of different manufacturers and different devices.

Description

Technical Field

[0001] This application relates to the field of semiconductor devices, and in particular to test methods for Desat protection circuits and devices with switchable protection times. Background Technology

[0002] Power semiconductor devices, such as IGBTs and MOSFETs, are mainly monolithic dies and packaged devices. Both monolithic dies and packaged devices require dynamic and static testing before leaving the production line to screen out defective chips or modules. Dynamic testing includes double-pulse testing and short-circuit testing. Double-pulse testing is a simple electrical test, while short-circuit testing is an electrothermal stress test.

[0003] The required protection time for short-circuit testing varies between different IGBT and SiC dies or devices, and the requirements also differ between manufacturers. For dies of third-generation power semiconductors, primarily SiC, the consistency is poor compared to IGBT dies, and the material dispersion of SiC is also significant. Therefore, SiC dies are generally tested before production to ensure good performance at packaging. Different semiconductor manufacturers have varying requirements for short-circuit testing of SiC dies, ranging from hundreds of ns to several microseconds. They may also require testing the die's ultimate short-circuit capability. This necessitates adjusting the Destination protection time to obtain the die's ultimate short-circuit time. However, exceeding the die's short-circuit tolerance time, if the driver IC's protection mechanism cannot be triggered to promptly shut down the die under test, it will cause die failure.

[0004] Currently, for testing or applications of different IGBT and SiC dies, the driver board design only has one matching short-circuit protection time. If the protection time needs to be changed, the resistors and capacitors on the board need to be manually changed to match the required protection parameters. This is not only inefficient and risky, but also cannot switch the protection time online in real time. Summary of the Invention

[0005] To meet the testing requirements of different power semiconductor devices and enable a single driver board to cover testing of different manufacturers and devices, this application provides a testing method for a Desat protection circuit and device with switchable protection time.

[0006] On the one hand, the Desat protection circuit with switchable protection time provided in this application adopts the following technical solution:

[0007] A switchable protection time Desat protection circuit includes: a driving unit, a time switching unit, and a status monitoring unit. The driving unit includes a first output terminal and a first input terminal. The time switching unit includes a second output terminal and a second input terminal. The status monitoring unit includes a first transmission terminal and a second transmission terminal. The first transmission terminal is electrically connected to the first output terminal, and a branch connection terminal is formed at the connection between the first transmission terminal and the first output terminal for connection to the second output terminal. The second transmission terminal is electrically connected to the first input terminal and is connected to a power supply terminal. The first transmission terminal and the second transmission terminal are used to connect to the power semiconductor device under test.

[0008] The status monitoring unit is used to monitor the voltage across the power semiconductor device under test, so that when a short-circuit test is performed on the power semiconductor device under test, after the voltage across the power semiconductor device under test exceeds a preset threshold voltage, a signal to shut down the power semiconductor device under test is sent to the driving unit after a preset protection time.

[0009] The time switching unit includes multiple time adjustment circuits, each equipped with an adjustment switch. The time switching unit controls the adjustment switch to connect the time adjustment circuit corresponding to the adjustment switch to the status monitoring unit, thereby switching the preset protection time.

[0010] By employing the above technical solution, the short-circuit test is used to test the short-circuit withstand time of a power semiconductor device, i.e., how long the power semiconductor device will not be damaged or malfunction. This application includes a status monitoring unit that monitors the voltage across the power semiconductor device under test. During a short-circuit test, the status monitoring unit can send a signal to the driving unit to shut down the power semiconductor device under test within a preset protection time to avoid damage to the power semiconductor device.

[0011] During short-circuit testing, the preset protection time is typically shorter than the short-circuit withstand time of power semiconductor devices. This application incorporates a time switching unit, which connects the corresponding time adjustment circuit to the status monitoring unit by closing an adjustment switch, thereby switching the preset protection time to meet the testing requirements of different power semiconductor devices. This allows a single driver board to cover testing of different manufacturers and devices. Furthermore, this application can continuously extend the preset protection time to test the ultimate short-circuit capability of power semiconductor devices.

[0012] The preset protection time can be switched by closing or opening the adjustment switch. Compared with the prior art, which requires manually changing the upper resistor and capacitor components on the board to match the required protection parameters, this application can switch the preset protection time in real time during testing. Specifically, when performing short-circuit testing on power semiconductor devices, the preset protection time can be switched by flexibly closing the adjustment switch to connect the corresponding adjustment resistor to the status monitoring unit. This eliminates the need to disconnect the board and manually change the components on the board, thus improving the testing efficiency of power semiconductor devices and reducing testing risks.

[0013] For example, the status monitoring unit includes a monitoring capacitor C1, and the two ends of the monitoring capacitor C1 respectively form the first transmission end and the second transmission end.

[0014] By adopting the above technical solution, after setting the status monitoring unit as the monitoring capacitor C1, when performing a short-circuit test on the power semiconductor device, the time consumed from the start of the short circuit to the drive unit turning off the power semiconductor device is mainly consumed by the following processes: First, the internal blanking time and filtering time of the drive unit. The internal blanking time is a time interval specified within the drive unit to ensure that the drive unit has enough time to detect overcurrent and take corresponding protective measures when turning off the power semiconductor device; Second, the charging time of the monitoring capacitor C1. The voltage across the monitoring capacitor C1 needs to be charged to exceed the preset charging voltage before the drive unit is triggered to turn off the power semiconductor device.

[0015] The internal blanking time and filtering time are both determined by the driving unit. When different driving ICs are used in the driving unit, the internal blanking time and filtering time are also different. In this application, the status monitoring unit is set as the monitoring capacitor C1. Changing the charging time of the monitoring capacitor C1 can change the preset protection time.

[0016] For example, multiple time adjustment circuits are connected in parallel. Each time adjustment circuit further includes an adjustment resistor with a first connection terminal and a second connection terminal. One end of the adjustment switch is connected to the second connection terminal of the adjustment resistor, and the other end is connected to the second output terminal. The first connection terminal of the adjustment resistor is connected to the second input terminal.

[0017] By adopting the above technical solution, each time adjustment circuit is equipped with an adjustment resistor. By connecting the time adjustment circuit to the monitoring capacitor C1, the charging current of the monitoring capacitor C1 can be changed to change the charging time of the monitoring capacitor C1.

[0018] For example, the resistance values ​​of the regulating resistors in different time-adjusting circuits are different.

[0019] By adopting the above technical solution, adjustable resistors with different resistance values ​​allow for personalized adjustments to the time adjustment circuit. Different time adjustment circuits correspond to different preset protection times. During short-circuit testing, if it is necessary to switch the preset protection time, only one adjustment switch needs to be closed at a time. At the same time, multiple adjustment switches can be closed to set more preset protection times to better adapt to different power semiconductor devices.

[0020] For example, the resistance values ​​of the regulating resistors in different time adjustment circuits are the same.

[0021] By adopting the above technical solution, using adjustable resistors with the same resistance value simplifies circuit design and debugging. While setting adjustable resistors with the same resistance value limits the range of switchable preset protection times, it reduces design complexity and improves production efficiency. Furthermore, although the adjustable resistors of Desat protection circuits with the same switchable protection time are set to the same value, the resistance value can be changed to design multiple Desat protection circuits with different ranges of switchable preset protection times. When performing short-circuit tests on power semiconductor devices, only a suitable Desat protection circuit with a switchable protection time needs to be selected.

[0022] For example, it also includes a protection unit, which includes a first protection resistor R1, a first diode D1, a second diode D2, and a third diode D3. The first protection resistor R1, the first diode D1, the second diode D2, and the third diode D3 each have a first connection terminal and a second connection terminal. The first connection terminal of the first protection resistor R1 is connected to the first transmission terminal, and the second connection terminal is connected to the first connection terminal of the first diode D1. The second connection terminal of the first diode D1 is connected to the first connection terminal of the second diode D2. The second connection terminal of the second diode D2 is used to connect to the power semiconductor device under test. The first connection terminal of the third diode D3 is connected to the second transmission terminal, and the second connection terminal of the second diode D2 is connected to the first transmission terminal.

[0023] By adopting the above technical solution, the first protective resistor R1 is mainly used to limit the current and prevent excessive current from damaging the components. The first diode D1 and the second diode D2 are used to provide a path for the reverse current, ensuring that the voltage does not become too high when the power semiconductor device under test is turned off, thereby preventing damage to the components in the circuit and maintaining circuit stability. The third diode D3 can prevent current from flowing back into the drive unit when the voltage of the monitoring capacitor C1 is higher than the voltage of the drive unit, preventing damage to the drive unit.

[0024] On the other hand, the device testing method provided in this application adopts the following technical solution:

[0025] A testing method for a device, the testing method being used for a power semiconductor device and applied to the aforementioned switchable protection time Desat protection circuit, includes the following steps:

[0026] Select the corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and close the adjustment switch of the time adjustment circuit to connect the time adjustment circuit to the status monitoring unit.

[0027] Connect the power semiconductor device under test to the switchable protection time Desat protection circuit;

[0028] A dual-pulse test was performed on the power semiconductor device under test;

[0029] A short-circuit test is performed on the power semiconductor device under test.

[0030] By adopting the above technical solution, the preset protection time can be switched by closing or opening the adjustment switch. Compared with the prior art, which requires manually changing the upper resistor and capacitor components on the board to match the required protection parameters, this application can switch the preset protection time online, which improves the testing efficiency of power semiconductor devices and reduces the testing risk.

[0031] In summary, selecting an appropriate preset protection time and activating a suitable time adjustment circuit for double-pulse and short-circuit testing helps improve the accuracy, efficiency, and reliability of the test, while protecting the power semiconductor device under test from damage.

[0032] For example, selecting a corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and closing the adjustment switch of the time adjustment circuit to connect the time adjustment circuit to the status monitoring unit includes:

[0033] Select a corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and close the adjustment switch of the time adjustment circuit.

[0034] Alternatively, multiple corresponding time adjustment circuits can be selected based on the preset protection time required by the power semiconductor device under test, and the adjustment switches corresponding to the multiple time adjustment circuits can be closed.

[0035] By adopting the above technical solution, selecting one or more corresponding time adjustment circuits and closing the corresponding adjustment switches, it is helpful to adapt to the testing requirements under different working conditions.

[0036] In summary, this application includes at least one of the following beneficial technical effects:

[0037] 1. This application incorporates a time switching unit. This unit connects the corresponding time adjustment circuit to the status monitoring unit via a closed adjustment switch, thereby switching the preset protection time to meet the testing requirements of different power semiconductor devices. This allows a single driver board to cover testing of different manufacturers and devices. Furthermore, this application can continuously extend the preset protection time to test the ultimate short-circuit capability of power semiconductor devices. The preset protection time can be switched simply by closing or opening the adjustment switch. Compared to existing technologies that require manual modification of the resistors and capacitors on the board to match the required protection parameters, this application allows for real-time switching of the preset protection time, improving the testing efficiency of power semiconductor devices and reducing testing risks.

[0038] 2. This application sets an adjustment resistor on each time adjustment circuit, connects the time adjustment circuit to the monitoring capacitor C1, and can change the magnitude of the charging current of the monitoring capacitor C1 to change the charging time of the monitoring capacitor C1. Attached Figure Description

[0039] Figure 1 This is a circuit diagram of a Desat protection circuit with switchable protection time.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Drive unit; 11. First output terminal; 12. First input terminal; 2. Time switching unit; 21. Second output terminal; 22. Second input terminal; 3. Status monitoring unit; 31. First transmission terminal; 32. Second transmission terminal; 33. Branch connection terminal; 4. Protection unit. Detailed Implementation

[0042] The present application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the scope of the application.

[0043] This application discloses a Desat protection circuit with switchable protection time. (Refer to...) Figure 1 A Desat protection circuit with switchable protection time includes: a driving unit 1, a time switching unit 2, and a status monitoring unit 3. The driving unit 1 is used to turn on or off the power semiconductor device under test, the time switching unit 2 is used to switch the preset protection time, and the status monitoring unit 3 is used to monitor the voltage across the power semiconductor device under test. When a short-circuit test is performed on the power semiconductor device under test, i.e., after the voltage across the power semiconductor device under test exceeds a preset threshold voltage, a signal to turn off the power semiconductor device under test is sent to the driving unit 1 after the preset protection time.

[0044] Specifically, the driving unit 1 includes a first output terminal 11 and a first input terminal 12, the time switching unit 2 includes a second output terminal 21 and a second input terminal 22, and the status monitoring unit 3 includes a first transmission terminal 31 and a second transmission terminal 32. The first transmission terminal 31 is electrically connected to the first output terminal 11, and a branch connection terminal 33 is formed at the connection between the first transmission terminal 31 and the first output terminal 11. The branch connection terminal 33 is connected to the second output terminal 21, the second transmission terminal 32 is electrically connected to the first input terminal 12, and the second input terminal 22 is connected to the power supply terminal. The first transmission terminal 31 and the second transmission terminal 32 are used to connect to the power semiconductor device under test.

[0045] In this embodiment, the driving unit 1 uses a readily available and mature driving IC. The status monitoring unit 3 includes a monitoring capacitor C1, with the two ends of the monitoring capacitor C1 forming a first transmission terminal 31 and a second transmission terminal 32, respectively. When performing a short-circuit test on a power semiconductor device, the time consumed from the short circuit of the power semiconductor device to the driving IC turning off the power semiconductor device to protect it mainly consists of the following processes: First, the internal blanking time and filtering time of the driving IC. The internal blanking time is a time interval specified within the driving IC to ensure that the driving unit 1 has sufficient time to detect overcurrent and take corresponding protective measures when turning off the power semiconductor device; second, the charging time of the monitoring capacitor C1. The voltage across the monitoring capacitor C1 needs to be charged to exceed a preset charging voltage before the driving unit 1 is triggered to turn off the power semiconductor device.

[0046] The internal blanking time and filtering time are both determined by the driver IC, and different driver ICs have different internal blanking and filtering times. Therefore, this application focuses on changing the charging time of the monitoring capacitor C1 to switch the protection time. Specifically, this application uses a time switching unit 2 to change the charging time of the monitoring capacitor C1. In this embodiment, the time switching unit 2 includes multiple time adjustment circuits connected in parallel, and each time adjustment circuit includes an adjustment switch and an adjustment resistor. The time switching unit 2 controls the adjustment switch to connect or disconnect the time adjustment circuit corresponding to the adjustment switch from the status monitoring unit 3 to switch the preset protection time.

[0047] Specifically, please refer to Figure 1 The regulating resistor has a first connection terminal and a second connection terminal. One end of the regulating switch is connected to the second connection terminal of the regulating resistor, and the other end is connected to the second output terminal 21. The first connection terminal of the regulating resistor is connected to the second input terminal 22. Furthermore, the number of time adjustment circuits can be set according to the actual test conditions. The resistance values ​​of the regulating resistors in different time adjustment circuits can be set to the same value or different values.

[0048] Furthermore, the switchable protection time Desat protection circuit disclosed in this application embodiment further includes a protection unit 4, which includes a first protection resistor R1, a first diode D1, a second diode D2, and a third diode D3. The first protection resistor R1, the first diode D1, the second diode D2, and the third diode D3 each have a first connection terminal and a second connection terminal. The first connection terminal of the first protection resistor R1 is connected to the first transmission terminal 31, and the second connection terminal is connected to the first connection terminal of the first diode D1. The second connection terminal of the first diode D1 is connected to the first connection terminal of the second diode D2, and the second connection terminal of the second diode D2 is used to connect to the power semiconductor device under test. The first connection terminal of the third diode D3 is connected to the second transmission terminal 32, and the second connection terminal of the third diode D3 is connected to the first transmission terminal 31.

[0049] The first protective resistor R1 is mainly used to limit the current and prevent excessive current from damaging the components. The first diode D1 and the second diode D2 are used to provide a path for the reverse current, ensuring that the voltage does not become too high when the power semiconductor device under test is turned off, thereby preventing damage to the components in the circuit and maintaining circuit stability. The third diode D3 can prevent current from flowing back into the drive unit 1 when the voltage of the monitoring capacitor C1 is higher than the voltage of the drive unit 1, preventing damage to the drive unit 1.

[0050] The implementation principle of this application embodiment is as follows: the state monitoring unit 3 is set to monitor the voltage across the power semiconductor device under test. When performing a double pulse test, the power semiconductor device is turned on, and the voltage across the power semiconductor device will not exceed the preset threshold voltage. At this time, the voltage across the monitoring capacitor C1 will also not exceed the preset charging voltage.

[0051] During a short-circuit test, if the voltage across the power semiconductor device exceeds a preset threshold voltage, the monitoring capacitor C1 will charge. After a preset protection time, the voltage across the monitoring capacitor C1 will exceed the preset charging voltage. When the voltage across the monitoring capacitor C1 exceeds the preset charging voltage, a signal to turn off the power semiconductor device will be sent to the drive unit 1 to ensure reliable shutdown of the power semiconductor device.

[0052] Before testing, this application selects one or more time adjustment circuits according to the power semiconductor device under test, closes the adjustment switch corresponding to the time adjustment circuit, so that the corresponding adjustment resistor is connected to the monitoring capacitor C1, thereby changing the charging current of the monitoring capacitor C1 during the short circuit test, and thus changing the charging time to achieve the switching of the preset protection time.

[0053] Embodiment 2 of this application discloses a testing method for a device. The testing method is used to test power semiconductor devices and is applied to the aforementioned switchable protection time Desat protection circuit. The method includes the following steps:

[0054] Select the corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and close the adjustment switch of the time adjustment circuit to connect the time adjustment circuit to the status monitoring unit 3.

[0055] Connect the power semiconductor device under test to a Desat protection circuit with switchable protection time;

[0056] Perform dual-pulse testing on the power semiconductor device under test;

[0057] Perform a short-circuit test on the power semiconductor device under test.

[0058] Specifically, the above-mentioned selection of a corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and closing the adjustment switch of the time adjustment circuit to connect the time adjustment circuit to the status monitoring unit 3 includes:

[0059] Select a corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and close the adjustment switch of the time adjustment circuit.

[0060] Alternatively, select multiple corresponding time adjustment circuits based on the preset protection time required by the power semiconductor device under test, and close the adjustment switches corresponding to the multiple time adjustment circuits.

[0061] This application allows switching of the preset protection time by closing or opening the adjustment switch. Compared with the prior art, which requires manually changing the upper resistor and capacitor components on the board to match the required protection parameters, this application can switch the preset protection time in real time, improving the testing efficiency of power semiconductor devices and reducing testing risks.

[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A Desat protection circuit with switchable protection time, characterized in that, include: The system comprises a drive unit (1), a time switching unit (2), and a status monitoring unit (3). The drive unit (1) includes a first output terminal (11) and a first input terminal (12). The time switching unit (2) includes a second output terminal (21) and a second input terminal (22). The status monitoring unit (3) includes a first transmission terminal (31) and a second transmission terminal (32). The first transmission terminal (31) is electrically connected to the first output terminal (11), and a branch connection terminal (33) is formed at the connection between the first transmission terminal (31) and the first output terminal (11) for connecting to the second output terminal (21). The second transmission terminal (32) is electrically connected to the first input terminal (12), and the second input terminal (22) is connected to the power supply terminal. The first transmission terminal (31) and the second transmission terminal (32) are used to connect to the power semiconductor device under test. The status monitoring unit (3) is used to monitor the voltage across the power semiconductor device under test, so that when the power semiconductor device under test is short-circuited, after the voltage across the power semiconductor device under test exceeds the preset threshold voltage, a signal to the driving unit (1) is sent to turn off the power semiconductor device under test after a preset protection time. The time switching unit (2) includes multiple time adjustment circuits, each of which is equipped with an adjustment switch. The time switching unit (2) controls the adjustment switch to connect the time adjustment circuit corresponding to the adjustment switch to the status monitoring unit (3) to switch the preset protection time. The status monitoring unit (3) includes a monitoring capacitor C1, and the two ends of the monitoring capacitor C1 respectively form the first transmission end (31) and the second transmission end (32); Multiple time adjustment circuits are connected in parallel. Each time adjustment circuit also includes an adjustment resistor. The adjustment resistor has a first connection terminal and a second connection terminal. One end of the adjustment switch is connected to the second connection terminal of the adjustment resistor, and the other end is connected to the second output terminal (21). The first connection terminal of the adjustment resistor is connected to the second input terminal (22).

2. The Desat protection circuit with switchable protection time according to claim 1, characterized in that, The resistance values ​​of the regulating resistors in different time-adjusting circuits are different.

3. The Desat protection circuit with switchable protection time according to claim 1, characterized in that, The resistance values ​​of the regulating resistors in the different time adjustment circuits are the same.

4. The Desat protection circuit with switchable protection time according to claim 1, characterized in that, It also includes a protection unit (4), which includes a first protection resistor R1, a first diode D1, a second diode D2 and a third diode D3. The first protection resistor R1, the first diode D1, the second diode D2 and the third diode D3 each have a first connection terminal and a second connection terminal. The first connection terminal of the first protection resistor R1 is connected to the first transmission terminal (31), and the second connection terminal is connected to the first connection terminal of the first diode D1. The second connection terminal of the first diode D1 is connected to the first connection terminal of the second diode D2. The second connection terminal of the second diode D2 is used to connect to the power semiconductor device under test. The first connection terminal of the third diode D3 is connected to the second transmission terminal (32), and the second connection terminal of the third diode D3 is connected to the first transmission terminal (31).

5. A testing method for a device, characterized in that, The test method is used for power semiconductor devices and applied to the Desat protection circuit with switchable protection time as described in any one of claims 1-4, and includes the following steps: Select the corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and close the adjustment switch of the time adjustment circuit to connect the time adjustment circuit with the status monitoring unit (3). Connect the power semiconductor device under test to the switchable protection time Desat protection circuit; A dual-pulse test was performed on the power semiconductor device under test; A short-circuit test is performed on the power semiconductor device under test.

6. The testing method for the device according to claim 5, characterized in that, The step of selecting a corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and closing the adjustment switch of the time adjustment circuit to connect the time adjustment circuit with the status monitoring unit (3) includes: Select a corresponding time adjustment circuit based on the preset protection time required by the power semiconductor device under test, and close the adjustment switch of the time adjustment circuit. Alternatively, multiple corresponding time adjustment circuits can be selected based on the preset protection time required by the power semiconductor device under test, and the adjustment switches corresponding to the multiple time adjustment circuits can be closed.

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