BD139-6 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 100
• 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 BD139-6 transistor can have a current gain of 40 to 100. The gain of the BD139 will be in the range from 40 to 250, for the BD139-10 it will be in the range from 63 to 160, for the BD139-16 it will be in the range from 100 to 250.The complementary PNP transistor to the BD139-6 is the BD140-6.The BCP56 (SOT-223) is the SMD version of the BD139-6 transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the BD139-6 with the 2N4923, 2N4923G, BD139G, BD169, BD179, BD230, BD237, BD237G, BD379, BD379-6, BD441, BD441G, BD789, BD791, MJE240, MJE241, MJE242, MJE243, MJE243G, MJE244 or MJE722.