This part is a kind of semiconductor called MPSW45A.

Function of this product has One Watt Darlington Transistors NPN Silicon.

Manufacturers : ON Semiconductor

Image and pinout :

Some of the text within the PDF file :

MPSW45, MPSW45A MPSW45A is a Preferred Device One Watt Darlington Transistors NPN Silicon Features http://onsemi.com COLLECTOR 3 BASE 2 Symbol MPSW45 MPSW45 VCES VCBO VEBO IC PD PD TJ, Tstg Value 40 50 50 60 12 1.0 1.0 8.0 2.5 20 Unit Vdc Vdc Vdc Adc W mW/°C W mW/°C 1 2 3 TO−92 (TO−226) CASE 29−10 STYLE 1 EMITTER 1 • Pb−Free Packages are Available* MAXIMUM RATINGS Rating Collector −Emitter Voltage MPSW45A Collector −Base Voltage MPSW45A Emitter −Base Voltage Collector Current − Continuous Total Device Dissipation @ TA = 25°C Derate above 25°C Total Device Dissipation @ TC = 25°C Derate above 25°C Operating and Storage Junction Temperature Range MARKING DIAGRAM −55 to +150 °C THERMAL CHARACTERISTICS Characteristic Thermal Resistance, Juncti [ ... ]

MPSW45A PDF Datasheet Download