The TOP227YN is a second generation, TOPSwitch-II three terminal off line PWM switch in 3 pin TO-220 package. It is a lowcost and lowest component count switcher solution. Many significant circuit enhancements that reduce sensitivity to board layout and line transients make the design easier. TOPSwitch-II family is more cost effective and provides several enhancements over first generation TOPSwitch family. It incorporates all functions necessary for switched mode control system into three terminal monolithic IC. The TOP227YN has built-in auto restart and current limiting features. It works with primary or opto feedback. The circuit simplicity and design tools reduce time to market. This PWM switch implements flyback, forward, boost or buck topologies. It integrates the high voltage power MOSFET, PWM control, fault protection and other control circuitry onto a single CMOS chip.