BD139 is a three-layer NPN or PNP device within the working range, the collector current IC is a function of the base current IB, a change in the base current giving a corresponding amplified change in the collector current for a given collector-emitter voltage VCE.
Features:-
- Low saturation voltage
- Simple drive requirements
- High safe operating area
- For low-distortion complementary designs
- Easy to carry and handle
