This part is a kind of semiconductor called 2SK1803.
Function of this product has Silicon N-Channel Power F-MOS FET.
Manufacturers : Panasonic
Image and pinout :
Some of the text within the PDF file :
Power F-MOS FETs 2SK1803 Silicon N-Channel Power F-MOS FET s Features q Avalanche capacity guaranteed: EAS > 60mJ q VGSS = ±30V guaranteed q High-speed switching: tf = 80ns q No secondary breakdown s Applications q Contactless relay q Diving circuit for a solenoid q Driving circuit for a motor q Control equipment q Switching power supply s Absolute Maximum Ratings (TC = 25°C) Parameter Symbol Ratings Drain to Source breakdown voltage Gate to Source voltage Drain current DC Pulse Avalanche energy capacity VDSS VGSS ID IDP EAS* 900 ±30 ±8 ±16 60 Allowable power dissipation TC = 25°C Ta = 25°C PD 100 3 Channel temperature Storage temperature Tch 150 Tstg −55 to +150 * L = 1.9mH, IL = 8A, VDD = 50V, 1 pulse Unit V V A A mJ W °C °C s Electrical Characteristics (TC = [ ... ]