The FSL126HR integrates a Pulse Width Modulator (PWM) and SenseFET is specifically designed for highperformance offline Switch-Mode Power Supplies (SMPS) with minimal external components. FSL126HR includes integrated high-voltage power switching regulators that combine an avalanche-rugged SenseFET with a current-mode PWM control block. The integrated PWM controller includes: Under-Voltage Lockout (UVLO) protection, Leading-Edge Blanking (LEB), a frequency generator for EMI attenuation, an optimized gate turn-on/turn-off driver, Thermal Shutdown (TSD) protection, and temperaturecompensated precision current sources for loop compensation and fault protection circuitry. The FSL126HR offers good soft-start performance. When compared to a discrete MOSFET and controller or RCC switching converter solution, the FSL126MR reduces total component count, design size, and weight; while increasing efficiency, productivity, and system reliability. This device provides a basic platform that is well suited for the design of cost-effective flyback converters.