This part is a kind of semiconductor called BFN37.

Function of this product has PNP Silicon High-Voltage Transistors.

Manufacturers : Infineon Technologies AG

Image and pinout :

Some of the text within the PDF file :

BFN37, BFN39 PNP Silicon High-Voltage Transistors
Suitabled for video output stages in TV sets and 4 switching power supplies
High breakdown voltage
Low collector-emitter saturation voltage
Complementary types: BFN36, BFN38 (NPN) 3 2 1 VPS05163 Type BFN37 BFN39 Maximum Ratings Parameter Marking BFN 37 BFN 39 1=B 1=B Pin Configuration 2=C 2=C 3=E 3=E 4=C 4=C Package SOT223 SOT223 Symbol VCEO VCBO VEBO BFN37 250 250 5 BFN39 300 300 5 Unit V Collector-emitter voltage Collector-base voltage Emitter-base voltage DC collector current Peak collector current Base current Peak base current Total power dissipation, TS = 124 °C Junction temperature Storage temperature IC ICM IB IBM Ptot Tj Tstg 200 500 100 200 1.5 150 -65 ... 150 mA W °C Thermal Resistance Junction - solde [ ... ]

BFN37 PDF Datasheet Download