This part is a kind of semiconductor called 2SB1644.

Function of this product has Power Transistor.

Manufacturers : Rohm

Image and pinout :

Some of the text within the PDF file :

Transistors Power Transistor (−80V, −4A) 2SB1644 2SB1644 !Features 1) Low saturation voltage. (Typ. VCE(sat) = −0.5V at IC / IB = −3A / −0.3A) 2) Excellent DC current gain characteristics. !External dimensions (Units : mm) 13.1 3.2 10.1 5.08 2.54 (3) (2) (1) 1.24 0.78 !Absolute maximum ratings (Ta = 25°C) Parameter Collector-base voltage Collector-emitter voltage Emitter-base voltage Collector current Collector power dissipation Junction temperature Storage temperature * Single pulse, Pw = 100ms Symbol VCBO VCEO VEBO IC PC Tj Tstg Limits −80 −80 −5 −4 −6 30 150 −55~+150 Unit V V V A (DC) *A (Pulse) W (Tc = 25°C) °C °C 8.8 1.3 4.5 1.3 0.4 0to0.3 0.5Min. ROHM : PSD3 EIAJ : SC-83A (1) Base (2) Collector (3) Emitter !Packaging specifications and hFE [ ... ]

2SB1644 PDF Datasheet Download