BD139 Transistor Pinout, Features, Alternate

BD139 transistor is a popular NPN type used in a variety of electronic circuits. It is an ideal transistor due to its high collector current and low cost. Due to these features, it is used in educational electronics projects as well as in commercial electronics circuits. This transistor can load up to 1.5A so you can drive high-current components like high-current relays, motors, LEDs, etc. It can easily survive in almost all electronic circuits because the collector-emitter and collector base voltage is very high up to 80 volts. It is also ideal to use in amplifier circuits due to 12.5W collector dissipation. The saturation voltages of BD139 are just 0.5V.

Pin Configurations of BD139

BD139 Transistor Pinout,Features,Alternate

NO  Pin Name Description
1 Emitter Current Drains out through the emitter
2 Collector Current flows in through the collector
3 Base Controls the biasing of the transistor, Used to turn ON & OFF.

Features / technical specifications of BD139

  • Plastic casing: NPN Transistor
  • Available Package: TO-126
  • Continuous Collector current(IC): 1.5A
  • Collector-Emitter voltage (VCE): 80V
  • Collector-Base voltage (VCB): 80V
  • Emitter Base Breakdown Voltage(VEBO): 5V
  • Collector Dissipation (Pc): 5 Watt
  • Max Transition Frequency (fT): 190 MHz
  • DC Current Gain (hFE): 25 – 250
  • Max Storage & Operating temperature: -55 to +150 Centigrade

BD139 Equivalent NPN Transistors

BD136, BD138,BD230, 2SC5171S, BD349, and BD379

Perfect Alternative to BD139 Transistor

D882 is the perfect alternative to BC139

PNP Complementary of BD139 Transistor

Complementary of BD139 is BD140


  • Switching circuits
  • RF Amplifiers circuit
  • Audio amplifiers applications
  • Amplification circuits
  • Load driver circuits

Where to use BD139 Transistor

This transistor was first manufactured by Philips rated at 160MHz especially for audio applications, later it was cloned by other manufacturers like ST, Samsung, etc.

Due to a high collector current of 1.5A, this transistor can be used to control (On/Off) high loads that consume less than 1.5A.  The saturation voltages (Base Emitter Voltage VBE) of only 5V, which makes it easy to use in digital electronics which has an operating voltage of 5V. It comes in a plastic jacket which is the way its cost is very less and the most important feature of a plastic jacket is that it will not be effect by other noise.

Datasheet of BD139

The datasheet of this transistor is given in this link.

Other NPN Transistors

BC547BC548, BC549, 2N2222AC945C1815

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