This part is a kind of semiconductor called SG3525A.

Function of this product has PULSE WIDTH MODULATOR CONTROL CIRCUITS.

Manufacturers : ON Semiconductor

Image and pinout :

Some of the text within the PDF file :

SG3525A Pulse Width Modulator Control Circuit The SG3525A pulse width modulator control circuit offers improved performance and lower external parts count when implemented for controlling all types of switching power supplies. The on−chip +5.1 V reference is trimmed to "1% and the error amplifier has an input common−mode voltage range that includes the reference voltage, thus eliminating the need for external divider resistors. A sync input to the oscillator enables multiple units to be slaved or a single unit to be synchronized to an external system clock. A wide range of deadtime can be programmed by a single resistor connected between the CT and Discharge pins. This device also features built−in soft−start circuitry, requiring only an external timing capacitor. A shutdown pin co [ ... ]

SG3525A PDF Datasheet Download