This part is a kind of semiconductor called FDT3612.

Function of this product has 100V N-Channel PowerTrench MOSFET.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

FDT3612 March 2001 FDT3612 100V N-Channel PowerTrench MOSFET General Description This N-Channel MOSFET has been designed specifically to improve the overall efficiency of DC/DC converters using either synchronous or conventional switching PWM controllers. These MOSFETs feature faster switching and lower gate charge than other MOSFETs with comparable RDS(ON) specifications. The result is a MOSFET that is easy and safer to drive (even at very high frequencies), and DC/DC power supply designs with higher overall efficiency. Features • 3.7 A, 100 V. RDS(ON) = 120 mΩ @ VGS = 10 V RDS(ON) = 130 mΩ @ VGS = 6 V • Fast switching speed • Low gate charge (14nC typ) • High performance trench technology for extremely low RDS(ON) • High power and current handling capability in a wide [ ... ]

FDT3612 PDF Datasheet Download