This part is a kind of semiconductor called MC34063.

Function of this product has DC/DC CONVERTER CONTROL CIRCUIT.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

MC34063 DC/DC CONVERTER CONTROL CIRCUIT Description The MC34063 is a monolithic control circuit containing the primary functions required for DC/DC converters. The device consists of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This device is specifically designed to be incorporated in stepdown, step-up and voltage-inverting applications with a minimum number of external components. The ±2% internal reference and low quiescent current of 1.6mA are among the improvements of the device over the competition Features  3V to 30V Input Voltage Operation.  Internal 1.2A Peak Current Switch.  Internal ±2% Reference.  Low Quiescent Current at 1.6mA.  Frequen [ ... ]

MC34063 PDF Datasheet Download