This document is an engineering report describing a 50 W power supply utilizing a TOP267EG. This power supply achieves >80% efficiency at 100 VAC 50Hz, full load output current of 10 A without employing secondary synchronous rectification. The EMI section is not designed for a typical 50 W power supply. The EMI components were chosen to resemble the input stage of a 200 W power supply unit. This is done to simulate EMI stage losses for a typical 200 W PSU in which this flyback converter will be the standby / auxiliary section of a complete system PSU. A 10ohm NTC is also employed to include the additional losses associated with any inrush limiting in the final system.