This part is a kind of semiconductor called AX3015C.

Function of this product has 2A PWM Buck DC/DC Converter.

Manufacturers : AXElite

Image and pinout :

Some of the text within the PDF file :

AX3015/A/B/C 2A PWM Buck DC/DC Converter  GENERAL DESCRIPTION The AX3015/A/B/C series are monolithic IC designed for a step-down DC/DC converter, and own the ability of driving a 2A load without additional transistor. It saves board space. The external shutdown function can be controlled by logic level and then come into standby mode. The internal compensation makes feedback control having good line and load regulation without external design. Regarding protected function, thermal shutdown is to prevent over temperature operating from damage; current limit is against over current operating of the output switch that set by outside resistance. Current limit depends on RSENSE value. The over voltage protection (OVP) that can avoid high VOUT voltage to damage circuit and capacitor, the OVP [ ... ]

AX3015C PDF Datasheet Download