This part is a kind of semiconductor called 2SK2078.
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 isc Product Specification 2SK2078 DESCRIPTION ·Drain Current ID= 9A@ TC=25℃ ·Drain Source Voltage- : VDSS= 800V(Min) ·Fast Switching Speed APPLICATIONS ·Switching regulators ·General purpose power amplifier ABSOLUTE MAXIMUM RATINGS(Ta=25℃) SYMBOL ARAMETER VALUE UNIT VDSS Drain-Source Voltage (VGS=0) VGS Gate-Source Voltage ID Drain Current-continuous@ TC=25℃ 800 ±30 9 V V A ID(puls) Pulsed Drain Current 27 A Ptot Total Dissipation@TC=25℃ 150 W Tj Max. Operating Junction Temperature 150 ℃ Tstg Storage Temperature Range -55~150 ℃ ·THERMAL CHARACTERISTICS SYMBOL PARAMETER MAX UNIT Rth j-c Rth j-a Thermal Resistance, Junction to Case 0.833 ℃/W Thermal Resistance, Junction to Ambient 50 ℃/W [ ... ]
2SK2078 PDF Datasheet Download
