What is short-circuit withstand capability?

Short-circuit withstand capability is the time it takes for a power device to break down when a load is short-circuited, and is expressed as SCWT or Tsc. In normal operation in a circuit using a power device, the current that flows between the drain and source (MOSFET) when the power device is turned on flows into the load connected to the circuit, generating load voltage. If the load is short-circuited in that state, current will flow while the power device is on, and the load will be short-circuited and the voltage will almost disappear, resulting in the current and voltage from the power supply being applied to the power device at the same time. When this happens, the temperature of the power device rises rapidly, exceeding the device rating and causing damage.
Short-circuit tolerance can be said to be a grace period for protection circuits that work to prevent device damage in the unlikely event of a load short-circuit.

As shown in the figure below, while the drain voltage (VDS) is applied, the MOSFET is turned on for a short period of time with the gate voltage to allow current to flow. Gradually increase the ON time until the device is damaged. It will not be damaged within the device's tolerance range, but will be damaged if the tolerance is exceeded. Since the drain current (Id) increases sharply when damaged, the short-circuit withstand capability is before that.
In addition, since high current and voltage are used, the measurement is dangerous.

For Microchip SiC-MOSFET

Microchip's SiC MOSFETs have a short-circuit withstand capability under certain conditions in their datasheets.
For example, in the case of products with withstand voltage ratings of 700V and 1200V, it is as follows.

700V product: 3uS (typ, Vds=560V / Vgs=20V)

1200V product: 3uS (typ, Vds=960V / Vgs=20V)

The short-circuit withstand voltage depends on the drain applied voltage, gate applied voltage, junction temperature, etc. When the applied voltage is small and the temperature is low, the withstand voltage tends to increase. As a reference, in Microchip's measurement example, it was about 10 µS at Vds 350 V for a 700 V withstand voltage SiC-MOSFET.
Microchip's SiC-MOSFETs will be very useful devices in applications that require short circuit tolerance.

Click here for Microchip SiC product information

• SiC discrete products (MOSFET, SBD)
• SiC power module products