BD139 80V 1.5A NPN Transistor TO126

BD139 NPN Transistor – 80V 1.5A Power Transistor in TO‑126 Package

The BD139 is a silicon NPN transistor rated for 80V collector-emitter voltage (V\_CEO\) and 1.5A continuous collector current. It supports up to 3A peak current and includes integrated current limiting and high gain (h\_FE\ from 40 to 250) depending on operating conditions.

Constructed in a TO‑126 (SOT‑32) package, the transistor handles up to 12.5W of power dissipation (at T\_C\=25°C) and withstands junction temperatures up to 150°C. The low saturation voltage (V\_CE(sat)\) of around 0.5V at 500mA (IB=50mA) ensures efficient conduction with minimal losses. With a transition frequency (f\_T\) of approximately 190MHz, it performs well in medium-frequency switching applications Instructables.

BD139 is widely used in audio amplifiers, switching circuits, and driver stages for both linear and saturation-mode operations in industrial, automotive, hobbyist, and consumer electronics systems.

Key Specs – BD139 NPN Transistor Collector‑Emitter Voltage (V\_CEO\): 80V Collector‑Base Voltage (V\_CBO\): 80V Emitter‑Base Voltage (V\_EBO\): 5V Collector Current (I\_C\): 1.5A Continuous, 3A Peak Pulse Power Dissipation (P\_D\): 12.5W at T\_C\=25°C DC Current Gain (h\_FE\): 40–250 (dependent on Ic and Vce) Saturation Voltage (V\_CE(sat)\): ~0.5V at Ic=500mA, Ib=50mA Transition Frequency (f\_T\): ~190MHz Package Type: TO‑126 (SOT‑32), Through‑Hole Applications: Audio amplifiers, switching circuits, voltage regulation, signal drivers Compliance: RoHS Compliant