This part is a kind of semiconductor called SSTA28.

Function of this product has NPN general purpose transistor.

Manufacturers : Rohm

Image and pinout :

Some of the text within the PDF file :

SSTA28 / MMSTA28 Transistors NPN general purpose transistor SSTA28 / MMSTA28 zFeatures 1) BVCES < 80V (Ic=100µA) zExternal dimensions (Unit : mm) SSTA28 2.9±0.2 zPackage, marking and packaging specifications Part No. Packaging type Marking Code Basic ordering unit (pieces) SSTA28 SST3 RAT T116 3000 MMSTA28 SMT3 RAT T146 3000 ROHM : SST3 JEDEC : SOT-23 (1) 1.9±0.2 0.95 0.95 (2) 0.95 +0.2 −0.1 0.45±0.1 0.2 1.3 + −0.1 2.4±0.2 0~0.1 0.2Min. (3) 0.4 +0.1 −0.05 +0.1 0.15 − 0.06 All terminals have same dimensions (1) Emitter (2) Base (3) Collector MMSTA28 2.9±0.2 1.9±0.2 0.95 0.95 zAbsolute maximum ratings (Ta=25°C) Parameter Collector-base voltage Collector-emitter voltage Emitter-base voltage Collector current Collector power dissipation Junctio [ ... ]

SSTA28 PDF Datasheet Download