BD139 Transistor Pinout,Features,Alternate

BD139 Transistor Pinout

BD139 transistor is a popular NPN type used in 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 circuit. This transistor can load upto1.5A so you can drive high current components like high current relays, motors, LEDs etc. It can easily survive in almost all electronics circuits because collector emitter and collector base voltage is very high upto 80 volts. It is also ideal to use in amplifier circuits due to 12.5W collector dissipation. The saturation voltages of BD139 are just0.5V.

Pin Configurations of BD139

BD139 Transistor Pinout

NO  Pin Name Description
1 Emitter Current Drains out through emitter
2 Collector Current flows in through collector
3 Base Controls the biasing of 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


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 firstly manufactured by Philips rated at 160MHz specially for audio applications, later it was cloned by other manufacturers like ST, Samsung etc.

Due to  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, this makes it easy to use in digital electronics which has an operating voltage of 5V. It comes in plastic jacket that is way its cost is very less and the most important feature of 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

BC547, BC548, BC549, 2N2222A, C945, C1815