This part is a kind of semiconductor called MT3420.

Function of this product has 2A Synchronous Step-Down DC/DC Converter.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

MT3420 1.4MHz, 2A Synchronous Step-Down DC/DC Converter FEATURES  High Efficiency: Up to 95%  1.4MHz Constant Frequency Operation  2A Output Current  No Schottky Diode Required  2.4V to 5.5V Input Voltage Range  Output Voltage as Low as 0.6V  Low Quiescent Current: 40µA  Slope Compensated Current Mode Control for Excellent Line and Load Transient Response  Inrush Current Limit and Soft Start  <1µA Shutdown Current  Available in DFN33-10 and WQFN-16L 3x3 package APPLICATIONS  Cellular and Smart Phones  Wireless and DSL Modems  PDAs  Digital Still and Video Cameras  PC Cards GENERAL DESCRIPTION The MT3420 is a constant frequency, current mode PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high [ ... ]

MT3420 PDF Datasheet Download