BD139 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 80 V
• Collector-Base Voltage, max: 100 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 1.5 A
• Collector Dissipation: 12.5 W
• DC Current Gain (h_fe): 40 to 250
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-126

Here is an image showing the pin diagram of this transistor.The BD139 transistor can have a current gain of 40 to 250. The gain of the BD139-10 will be in the range from 63 to 160, for the BD139-16 it will be in the range from 100 to 250, for the BD139-6 it will be in the range from 40 to 100.The complementary PNP transistor to the BD139 is the BD140.The BCP56 (SOT-223) is the SMD version of the BD139 transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the BD139 with the BD139G, BD169, BD179, BD230, BD237, BD237G, BD379, BD789, BD791, MJE242, MJE244 or MJE722.The BD139G transistor is the lead-free version of the BD139.