This part is a kind of semiconductor called 18N50.
Function of this product has N-Channel Mosfet Transistor.
Manufacturers : Inchange Semiconductor
Image and pinout :
Some of the text within the PDF file :
INCHANGE Semiconductor isc N-Channel MOSFET Transistor ·DESCRIPTION ·Drain Current ID= 18A@ TC=25℃ ·Drain Source Voltage : VDSS= 500V(Min) ·Static Drain-Source On-Resistance : RDS(on) = 0.32Ω(Max) ·Fast Switching ·APPLICATIONS ·Switch regulators ·Switching converters, motor drivers, relay drivers isc Product Specification 18N50 ·ABSOLUTE MAXIMUM RATINGS(Ta=25℃) SYMBOL PARAMETER VALUE UNIT VDSS VGS Drain-Source Voltage Gate-Source Voltage-Continuous 500 ±20 V V ID Drain Current-Continuous 18 A IDM Drain Current-Single Plused 72 A PD Total Dissipation @TC=25℃ 38.5 W Tj Max. Operating Junction Temperature 150 ℃ Tstg Storage Temperature -55~150 ℃ ·THERMAL CHARACTERISTICS SYMBOL PARAMETER Rth j-c Thermal Resistance, Junction to Case Rth j-a Thermal R [ ... ]