This part is a kind of semiconductor called TOP200YAI.

Function of this product has Three-terminal Off-line PWM Switch.

Manufacturers : Power Integrations

Image and pinout :

Some of the text within the PDF file :

TOP200-4/14 TOPSwitch® Family Three-terminal Off-line PWM Switch ® Product Highlights Low Cost Replacement for Discrete Switchers • 20 to 50 fewer components - cuts cost, increases reliability • Source-connected tab and Controlled MOSFET turn-on reduce EMI and EMI filter costs • Allows for a 50% smaller and lighter solution • Cost competitive with linears above 5 W Up to 90% Efficiency in Flyback Topology • Built-in start-up and current limit reduce DC losses • Low capacitance 700 V MOSFET cuts AC losses • CMOS controller/gate driver consumes only 6 mW • 70% maximum duty cycle minimizes conduction losses Simplifies Design - Reduces Time to Market • Supported by many reference design boards • Integrated PWM Controller and 700 V MOSFET in a industry standard three pin [ ... ]

TOP200YAI PDF Datasheet Download