This part is a kind of semiconductor called BD637.

Function of this product has Silicon NPN Power Transistor.

Manufacturers : Inchange Semiconductor

Image and pinout :

Some of the text within the PDF file :

INCHANGE Semiconductor isc Product Specification isc Silicon NPN Power Transistor BD637 DESCRIPTION ·DC Current Gain : hFE = 40(Min.)@ IC= 25mA ·Collector-Emitter Breakdown Voltage: V(BR)CEO= 80V(Min.) ·Complement to Type BD638 APPLICATIONS ·Designed for amplifier and switching applications. ABSOLUTE MAXIMUM RATINGS(Ta=25℃) SYMBOL VCBO VCEO VEBO IC ICM IB B PARAMETER Collector-Base Voltage Collector-Emitter Voltage Emitter-Base Voltage Collector Current-Continuous Collector Current-Peak Base Current-Continuous Collector Power Dissipation @ Ta=25℃ VALUE 100 80 5 2 5 0.3 2 UNIT V V V A A A PC Collector Power Dissipation @ TC=25℃ TJ Tstg Junction Temperature Storage Temperature Range 30 150 -55~150 W ℃ ℃ isc Website：www.iscsemi.cn Free Datasheet http://www.datash [ ... ]

BD637 PDF Datasheet Download