This part is a kind of semiconductor called KA3845B.

Function of this product has SMPS Controller.

Manufacturers : Fairchild

Image and pinout :

Some of the text within the PDF file :

www.fairchildsemi.com KA3842B/KA3843B/KA3844B/ KA3845B SMPS Controller Features • Low Start up Current • Maximum Duty Clamp • UVLO With Hysteresis • Operating Frequency up to 500KHz Description The KA3842B/KA3843B/KA3844B/KA3845B are fixed frequency current-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 KA3842B and KA3844B have UVLO thresholds of 16V (on) and 10V (off). The KA3843B and KA3845B are 8.5V (on) and 7.9V (off). The KA3842B and KA3843B can op [ ... ]

KA3845B PDF Datasheet Download