This part is a kind of semiconductor called TOP223YN.

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 :

This product is not recommended for new designs. TOP221-227 TOPSwitch-II Family Three-Terminal Off-Line PWM Switch Product Highlights • Lowest cost, lowest component count switcher solution • Cost competitive with linears above 5 W • Very low AC/DC losses – up to 90% efficiency • Built-in Auto-restart and Current limiting • Latching Thermal shutdown for system level protection • Implements Flyback, Forward, Boost or Buck topology • Works with primary or opto feedback • Stable in discontinuous or continuous conduction mode • Source connected tab for low EMI • Circuit simplicity and Design Tools reduce time to market Description The second generation TOPSwitch™-II family is more cost effective and provides several enhancements over the first generation TOPS [ ... ]

TOP223YN PDF Datasheet Download