The MK91808H is a compact secondary side synchronous rectifier controller and driver for high performance flyback converters. It is optimized for both ACF and high frequency QR. It is compatible with DCM, CCM and QR operations. The MK91808H generates its own supply while used in high-side rectification, which eliminates the need of external supply generated by auxiliary winding of the transformer. The extremely low 10ns turn−off propagation delay time and high sink current (~4A) capability of the driver improve SR VDS stress at CCM mode. The unique VG clamping circuit works well to prevent VG from turning on by fast rising at VD pin with no VCC, that avoids the shoot through between primary side and secondary side during system startup even if the SR VCC is still below 2V.