This document describes a 15-W flyback switched mode power supply (SMPS) application that uses an emitter-switched bipolar transistor (ESBT™) switch (STC03DE220HV) and L6565 quasi-resonant pulse-width modulation (PWM) controller. The application is a universal, cost-effective flyback converter used in metering applications, with an excellent wide-voltage input range from 125 to 1250 VDC, achieved using the ESBT as the main switch and a quasi-resonant PWM driver.