This part is a kind of semiconductor called 5Q1265RT.

Function of this product has KA5Q1265RT.

Manufacturers : Fairchild

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Some of the text within the PDF file :

Preliminary KA5Q1265RT SPS The SPS product family is specially designed for an off-line SMPS with minimal external components. The SPS consist of high voltage power SenseFET and current mode PWM IC. Included PWM controller features integrated fixed oscillator, under voltage lock out, leading edge blanking, optimized gate turn-on/turnoff driver, thermal shut down protection, over voltage protection, and temperature compensated precision current sources for loop compensation and fault protection circuitry. Compared to discrete MOSFET and controller or RCC switching converter solution, a SPS can reduce total component count, design size, and weight and at the same time increase efficiency, productivity, and system reliability. It has a basic platform well suited for cost-effective design in Q [ ... ]

5Q1265RT PDF Datasheet Download