公开(公告)号：US20210143730A1

公开(公告)日：2021-05-13

申请号：US17075576

申请日：2020-10-20

Applicant: Richtek Technology Corporation

Inventor： Ta-Yung Yang ,  Kwan-Jen Chu

IPC: H02M1/34 ,  H02M3/335

Abstract: A flyback power converter includes: a transformer, a primary side switch, a snubber capacitor and an active clamp snubber. The snubber capacitor is charged by a leakage inductance current of a primary winding fora snubber period following after a time point when the primary side switch is turned OFF. The active clamp snubber includes a snubber control switch which is connected in series to the snubber capacitor. The series circuit of the snubber control switch and the snubber capacitor is connected in parallel to the primary winding. The leakage inductance current charges the snubber capacitor through the snubber control switch during the snubber period. The snubber capacitor provides a capacitor voltage as electrical power of the active clamp snubber. A voltage level of a reference node between the snubber control switch and the snubber capacitor serves as a snubber ground level of the active clamp snubber.