JAJU510H March 2018 – December 2022
Figure 2-43 shows the schematic design of the isolated SiC MOSFET gate driver. VCC and GND are the supply pins for the input side of the UCC21710 device. The supply voltage at VCC can range from 3.0 V to 5.5 V with respect to GND. VDD and COM are the supply pins for the output side of the UCC21710 device. VEE is the supply return for the output driver and COM is the reference for the logic circuitry. The supply voltage at VDD can range from 15 V up to 30 V with respect to VEE. The PWM is applied across the IN+ and IN– pins of the gate driver.
On the secondary-side of the gate driver, gate resistors R308 and R307 control the gate current of the switching device. The DESAT fault detection prevents any destruction resulting from excessive collector currents during a short-circuit fault. To prevent damage to the switching device, the UCC21710 slowly turns off the SiC MOSFET in the event of a fault detection. A slow turnoff makes sure the overcurrent is reduced in a controlled manner during the fault condition. The DESAT diode D301 conducts the bias current from the gate driver, which allows sensing of the MOSFET-saturated collector-to-emitter voltage when the SiC MOSFET is in the ON condition.