This part is a kind of semiconductor called XL4012.

Function of this product has 12A 300KHz 32V Buck DC to DC Converter.

Manufacturers : Xlsemi

Image and pinout :

Some of the text within the PDF file :

12A 300KHz 32V Buck DC to DC Converter Datasheet XL4012 Features „ Wide 5V to 32V Input Voltage Range „ Output Adjustable from 0.8V to 30V „ Maximum Duty Cycle 100% „ Minimum Drop Out 0.6V „ Fixed 300KHz Switching Frequency „ 12A Constant Output Current Capability „ Internal Optimize Power MOSFET „ High efficiency „ Excellent line and load regulation „ Built in thermal shutdown function „ Built in current limit function „ Built in output short protection function „ Available in TO-220 package Applications „ LCD Monitor and LCD TV „ Digital Photo Frame „ Set-up Box „ ADSL Modem „ Telecom / Networking Equipment General Description The XL4012 is a 300 KHz fixed frequency PWM buck (step-down) DC/DC converter, capable of driving a 12A load with high efficiency, low ripple a [ ... ]

XL4012 PDF Datasheet Download