This part is a kind of semiconductor called UC2845.

Function of this product has (UC2844 / UC2845) High Performance Current Mode Controllers.

Manufacturers : ON Semiconductor

Image and pinout :

Some of the text within the PDF file :

UC3844, UC3845, UC2844, UC2845 High Performance Current Mode Controllers The UC3844, UC3845 series are high performance fixed frequency current mode controllers. They are specifically designed for Off−Line and DC−to−DC converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle−by−cycle current limiting, a latch for single pulse metering, and a flip−flop which blanks the output off every other os [ ... ]

UC2845 PDF Datasheet Download