This part is a kind of semiconductor called AX3484.

Function of this product has 340kHz Synchronous Rectified Step-Down Converter.

Manufacturers : AXElite

Image and pinout :

Some of the text within the PDF file :

AX3484 3A, 23V, 340kHz Synchronous Rectified Step-Down Converter  GENERAL DESCRIPTION The AX3484 is a monolithic synchronous buck regulator. The device integrates two 100mΩ MOSFETs, and provides 3A of continuous load current over a wide input voltage of 4.75V to 23V. Current mode control provides fast transient response and Cycle-by-Cycle current limit. An adjustable soft-start prevents inrush current at turn-on, and in shutdown mode the supply current drops to 1μA. This device, available in an 8-pin SOP with exposed pad package, provides a very compact solution with minimal external components.  FEATURES - 3A Output Current - Wide 4.75V to 23V Operating Input Range - Integrated 100mΩ Power MOSFET Switches - Output adjust from VFB to 20V - Up to 95% Efficiency - Programmable Soft- [ ... ]

AX3484 PDF Datasheet Download