This part is a kind of semiconductor called APM2509NU.
Function of this product has N-Channel Enhancement Mode MOSFET.
Manufacturers : Anpec Electronics Coropration
Image and pinout :

Some of the text within the PDF file :
www.datasheet4u.com APM2509NU N-Channel Enhancement Mode MOSFET Features • 25V/50A , RDS(ON)=7.5mΩ(typ.) @ VGS=10V RDS(ON)=13mΩ(typ.) @ VGS=4.5V Pin Description • • • • Super High Dense Cell Design Avalanche Rated Reliable and Rugged Lead Free Available (RoHS Compliant) D Top View of TO-252 Applications • G Power Management in Desktop Computer or DC/DC Converters S N-Channel MOSFET Ordering and Marking Information APM2509N Lead Free Code Handling Code Temp. Range Package Code Package Code U : TO-252 Operating Junction Temp. Range C : -55 to 150 ° C Handling Code TU : Tube TR : Tape & Reel Lead Free Code L : Lead Free Device Blank : Original Device XXXXX - Date Code APM2509N U : APM2509N XXXXX Note: ANPEC lead-free products contain molding compounds/die attach [ ... ]
APM2509NU PDF Datasheet Download
