This is one of the semiconductor types. This part name is 5Q1265RF.
This product has KA5Q1265RF functions.
Manufacturers of product is Fairchild.
Image and pinout :
5Q1265RF PDF Datasheet
Some of the text files within the PDF file
www.fairchildsemi.com KA5Q-SERIES KA5Q0765RT/KA5Q12656RT/KA5Q1265RF/ KA5Q1565RF Fairchild Power Switch(FPS) Features • Quasi Resonant Converter Controller Internal Burst Mode Controller for Stand-by Mode Pulse by Pulse Current Limiting Over Current Latch Protection Over Voltage Protection (Vsync: Min. 11V) Internal Thermal Shutdown Function Under Voltage Lockout Internal High Voltage Sense FET Auto-Restart Mode
The Fairchild Power Switch(FPS) product family is specially designed for an off-line SMPS with minimal external components. The Fairchild Power Switch(FPS) consist of high voltage power SenseFET and current mode PWM controller IC. PWM controller features integrated fixed oscillator, under voltage lock out, leading edge blanking, optimized gate turn-on/ turn-off driver, thermal shut down protection, over voltage protection, temperature compensated precision current sources for loop compensation and fault protec [ … ]
Please refer to the file for details.