This part is a kind of semiconductor called W15NB50.

Function of this product has STW15NB50.

Manufacturers : ST Microelectronics

Image and pinout :

Some of the text within the PDF file :

ST W15NB50 ST H15NB50FI s s s s s s w w at .D w h S a ® ee U 4 t m o .c STW15NB50 STH15NB50FI N-CHANNEL 500V - 0.33Ω - 14.6A T0-247/ISOWATT218 PowerMESH™ MOSFET V DSS 500 V 500 V R DS(on) < 0.36 Ω < 0.36 Ω ID 14.6 A 10.5 A TYPE TYPICAL RDS(on) = 0.33 Ω EXTREMELY HIGH dv/dt CAPABILITY ± 30V GATE TO SOURCE VOLTAGE RATING 100% AVALANCHE TESTED VERY LOW INTRINSIC CAPACITANCES GATE CHARGE MINIMIZED 3 DESCRIPTION Using the latest high voltage MESH OVERLAY™ process, SGS-Thomson has designed an advanced family of power MOSFETs with outstanding performances. The new patent pending strip layout coupled with the Company’s proprietary edge termination structure, gives the lowest RDS(on) per area, exceptional avalanche and dv/dt capabilities and unrivall [ ... ]

W15NB50 PDF Datasheet Download