BD139 Transistor (NPN, 80V, 1.5A)

BD139 NPN Bipolar Transistor

The BD139 is an NPN transistor for compatible audio amplifier, driver and switching circuits. It is commonly used with the complementary PNP BD140 in circuit designs that require both polarities.

Key specifications

• Polarity: NPN.
• Collector-emitter voltage rating: 80V.
• Collector current rating: 1.5A.
• Package: TO-126/SOT-32 style, three leads.

Design and replacement checks

The voltage and current figures are absolute maximum ratings. They do not mean the transistor can dissipate their product as heat; check its safe operating area, power dissipation and cooling for the intended circuit.

Verify the manufacturer marking, gain grade and lead arrangement before fitting. Provide appropriate base-current limiting and, when switching an inductive load, suitable transient suppression.

STMicroelectronics BD135/BD139/BD140 family reference datasheet