This part is a kind of semiconductor called FSD210B.

Function of this product has Green Mode Fairchild Power Switch.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

www.fairchildsemi.com FSD210B, FSD200B Features • Single Chip 700V Sense FET Power Switch for 7DIP • Precision Fixed Operating Frequency (134KHz) • FSD210B Consumes Under 0.1W at 265VAC & No Load with Advanced Burst-Mode Operation • Internal Start-up Circuit • Pulse-by-Pulse Current Limiting • Over Load Protection (OLP) • Internal Thermal Shutdown Function (TSD) • Auto-Restart Mode • Under Voltage Lockout (UVLO) with Hysteresis • Built-in Soft Start • Frequency Modultation for EMI Reduction • FSD200B Does Not Require an Auxiliary Bias Winding Green Mode Fairchild Power Switch (FPSTM) OUTPUT POWER TABLE PRODUCT FSD210B FSD200B FSD210BM FSD200BM 85-265VAC 230VAC ±15%(3) Open Open Adapter(1) Adapter(1) Frame(2) Frame(2) 5W 7W 4W 5W 5W 7W 4W 5W 5W 7W 4W 5W 5W 7W 4W 5 [ ... ]

FSD210B PDF Datasheet Download