This part is a kind of semiconductor called KF5N50FS.

Function of this product has N CHANNEL MOS FIELD EFFECT TRANSISTOR.

Manufacturers : KEC

Image and pinout :

Some of the text within the PDF file :

SEMICONDUCTOR TECHNICAL DATA General Description This planar stripe MOSFET has better characteristics, such as fast switching time, fast reverse recovery time, low on resistance, low gate charge and excellent avalanche characteristics. It is mainly suitable for electronic ballast and switching mode power supplies. FEATURES VDSS= 500V, ID= 5.0A Drain-Source ON Resistance : RDS(ON)=1.4 Qg(typ) = 12nC trr(typ) = 150ns D KF5N50PR/FR/PS/FS N CHANNEL MOS FIELD EFFECT TRANSISTOR KF5N50PR, KF5N50PS A O C F E G B Q I K P M L J N N H @VGS = 10V MAXIMUM RATING (Tc=25 ) RATING DIM MILLIMETERS _ 0.2 9.9 + A 15.95 MAX B 1.3+0.1/-0.05 C _ 0.1 D 0.8 + _ 0.2 E 3.6 + _ 0.1 F 2.8 + 3.7 G H 0.5+0.1/-0.05 1.5 I _ 0.3 13.08 + J K 1.46 _ 0.1 1.4 + L _ 0.1 1.27+ M _ 0.2 2.54 + N _ 0.2 4.5 + O _ 0.2 2.4 + [ ... ]

KF5N50FS PDF Datasheet Download