TIDUF22 January 2023
There are three types of current protections in this design.
Cycle-By-Cycle current protection: TMS320F280025C has comparator subsystems (CMPSS), windowed comparators, which can protect overcurrent in both positive and negative half cycles. In this design, software set at 40-A current triggers CMPSS. CMPSS is configured as cycle-by-cycle protection.
GaN overcurrent protection: GaN pulls down the FAULT signals at overcurrent. The top and bottom FAULT signal are ANDed and reported to TMS320F280025C to create a trip zone (TZ) signal to stop PWM, this is a one-shot-trip protection. Typical drain overcurrent for LMG3522R030 is 70 A.
Overload current protection: software monitors AC input current and stops PFC if the load current is too high. In this design, overload current is set to 26 ARMS in software.