This part is a kind of semiconductor called BCW31.

Function of this product has NPN General Purpose Amplifier.

Manufacturers : Fairchild Semiconductor

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Some of the text within the PDF file :

BCW31 BCW31 NPN General Purpose Amplifier • This device is designed for general purpose applications at collector currents to 300mA. • Sourced from process 10. 3 2 1 SOT-23 Mark: D1 1. Base 2. Emitter 3. Collector Absolute Maximum Ratings * Ta=25°C unless otherwise noted Symbol Parameter VCEO Collector-Emitter Voltage VCBO Collector-Base Voltage VEBO Emitter-Base Voltage IC Collector current (DC) TJ, Tstg Operating and Storage Junction Temperature Range * These ratings are limiting values above which the serviceability of any semiconductor device may be impaired. Value 32 32 5.0 500 -55 ~ +150 NOTES: 1) These ratings are based on a maximum junction temperature of 150 degrees C. 2) These are state limits. The factory should be consulted on applications involving p [ ... ]

BCW31 PDF Datasheet Download