This part is a kind of semiconductor called KF5N50FSA.

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 (KF5N50FSA) trr(typ) = 300ns (KF5N50FZA) @VGS = 10V KF5N50FZA/FSA N CHANNEL MOS FIELD EFFECT TRANSISTOR MAXIMUM RATING (Tc=25 ) CHARACTERISTIC Drain-Source Voltage Gate-Source Voltage @TC=25 Drain Current @TC=100 Pulsed (Note1) Single Pulsed Avalanche Energy (Note 2) Repetitive Avalanche Energy (Note 1) Peak Diode Recovery dv/dt (Note 3) Drain Power Dissipation Tc=25 Derate ab [ ... ]

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