This part is a kind of semiconductor called UC3843.

Function of this product has (UC3842 - UC3845) SMPS Controller.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

www.fairchildsemi.com UC3842/UC3843/UC3844/UC3845 SMPS Controller Features • • • • Low Start up Current Maximum Duty Clamp UVLO With Hysteresis Operating Frequency up to 500KHz Description The UC3842/UC3843/UC3844/UC3845 are fixed frequencycurrent-mode PWM controller. They are specially designed for Off-Line and DC to DC converter applications with minimum external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totempole output for driving a Power MOSFET. The UC3842 and UC3844 have UVLO thresholds of 16V (on) and 10V (off). The UC3843 and UC3845 are 8.5V(on) and 7.9V (off). The UC3842 and UC3843 can [ ... ]

UC3843 PDF Datasheet Download