Hi expert,
I'm designing a high PFC single stage flyback using UCC28810 as the controller. I found that some reference designs use voltage regulation circuit in the start-up & aux winding circuit.
Due to the limited size of my PCB board, I would like to connect the start-up RC directly to VDD adding a 18V TVS, shown as below. Is it ok for UCC28810? Please help review and give some comments.