This part is a kind of semiconductor called AX4102.

Function of this product has PWM Control 3.5A Step-Down Converter.

Manufacturers : AXElite

Image and pinout :

Some of the text within the PDF file :

www.net AX4102 PWM Control 3.5A Step-Down Converter ™ GENERAL DESCRIPTION AX4102 consists of step-down switching regulator with PWM control. These devise include a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc. AX4102 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to the duty ratio linearly form 0 up to 100%. An enable function, an over current protect function and short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced. Also, an internal compensation block is built in to minimum external component count. With the addition of an internal P-channel Power MOS, a coil, capacitors, and a diode connected extern [ ... ]

AX4102 PDF Datasheet Download