The Fairchild Power Switch(FPS) product family is specially designed for an off line SMPS with minimal external components. The Fairchild Power Switch(FPS) consists of a high voltage power SenseFET and the current mode PWM controller IC. The PWM controller includes an integrated fixed oscillator, the under voltage lock out, the leading edge blanking block, the optimized gate turn-on/turn-off driver, the thermal shut down protection, the over voltage protection, the temperature compensated precision current sources for loop compensation and an fault protection circuit. Compared to just PWM controller combined MosFET or RCC switching converter solution, a Fairchild Power Switch(FPS) can reduce total component price, design size, and weight,also simultaneously increase efficiency, productivity, and system reliability. It has a simple method of application well suited for cost down design in either a flyback converter or a forward converter.