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BD139 NPN Power Transistor

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NPN medium-power transistor, 80 V / 1.5 A, in a TO-126 package for audio and driver stages.

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Made with kicad-footprint-generator 10.0 · KiCad file format 20260206
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docs bd139: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray 1mo ago
viewers viewers · Ray 2mo ago
bd139-etched.fit.json bd139: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray 1mo ago
bd139-etched.glb bd139: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray 1mo ago
bd139-etched.step bd139: re-etch, flat white mark read from pin 1 (service-occt 1.4.0) + chip hero · Ray 1mo ago
BD139.adom-lbr.json BD139: validated Fusion/EAGLE library + adom-lbr hub, generated from this page's KiCad sources · Ray 2mo ago
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BD139.lbr BD139: validated Fusion/EAGLE library + adom-lbr hub, generated from this page's KiCad sources · Ray 2mo ago
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page.json bd139: specified limits as data (metadata.characteristics, 21 rows from the datasheet) · Ray 26d ago
README.md bd139: specified limits as data (metadata.characteristics, 21 rows from the datasheet) · Ray 26d ago

BD139

STMicroelectronics · Bipolar Transistor (BJT) · TO-126

The BD139 is an NPN medium-power transistor rated for 80 V and 1.5 A continuous collector current in a TO-126 package. It is widely used in audio amplifier output and driver stages, discrete linear regulators, and general medium-power switching. Its complement is the BD140 PNP.

Pinout

Pin Name Type Function
1 E passive Emitter terminal of the NPN BJT. Absolute maximum VEBO = 5 V. Typically returned to ground or a low-impedance node in common-emitter audio driver stages.
2 C passive Collector terminal of the NPN BJT. Absolute maximum VCEO = 80 V, VCBO = 80 V. Continuous IC = 1.5 A, peak ICM = 3 A. VCE(sat) ≤ 0.5 V at IC = 0.5 A, IB = 0.05 A. Collector tab is electrically common to the metal mounting tab of the SOT-32 package.
3 B input Base terminal of the NPN BJT. Absolute maximum base current IB = 0.5 A. Typical VBE ≈ 1 V at IC = 0.5 A, VCE = 2 V. Drives collector current via hFE (40-250 at IC = 150 mA).

Key specifications

Parameter Value
Type NPN medium-power transistor
Collector-emitter voltage (VCEO) 80 V
Collector current (IC) 1.5 A continuous (3 A peak)
DC current gain (hFE) 40 to 250
Transition frequency (fT) 190 MHz
Power dissipation 12.5 W
Operating temperature -55 C to 150 C

Ordering variants

  • BD139
  • BD139-10
  • BD139-16

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Collector-emitter sustaining voltage (IB=0), BD139 VCEO(sus) 80 V IC = 30 mA (pulsed, 300 µs, duty cycle 1.5%) 4
Collector cut-off current (IE=0), NPN ICBO 0.1 µA VCB = 30 V 4
Collector cut-off current (IE=0), NPN, hot ICBO 10 µA VCB = 30 V, TC = 125 °C 4
Emitter cut-off current (IC=0), NPN IEBO 10 µA VEB = 5 V 4
Collector-emitter saturation voltage, NPN VCE(sat) 0.5 V IC = 0.5 A, IB = 0.05 A 4
Base-emitter voltage, NPN VBE 1 V IC = 0.5 A, VCE = 2 V 4
DC current gain, NPN hFE 25 IC = 5 mA, VCE = 2 V 4
DC current gain, NPN hFE 40 IC = 150 mA, VCE = 2 V 4
DC current gain, NPN (max for the three printed conditions) hFE 250 IC = 5 mA, VCE = 2 V; IC = 150 mA, VCE = 2 V; IC = 0.5 A, VCE = 2 V 4
Collector-base voltage (IE = 0), BD139 VCBO 80 V IE = 0 3
Collector-emitter voltage (IB = 0), BD139 VCEO 80 V IB = 0 3
Emitter-base voltage (IC = 0) VEBO 5 V IC = 0 3
Collector current IC 1.5 A 3
Collector peak current ICM 3 A 3
Base current IB 0.5 A 3
Total dissipation PTOT 12.5 W Tc ≤ 25 °C 3
Total dissipation PTOT 1.25 W Tamb ≤ 25 °C 3
Storage temperature Tstg -65 150 °C 3
Max. operating junction temperature Tj 150 °C 3
Thermal resistance junction-case Rthj-case 10 °C/W 3
Thermal resistance junction-ambient Rthj-amb 100 °C/W 3

CAD (KiCad official)

  • Symbol: bd139.kicad_sym
  • Footprint: bd139.kicad_mod
  • 3D model: TO-126 body from KiCad Package_TO_SOT_THT/TO-126-3_Vertical.
  • 3D model files: bd139-etched.step / bd139-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); bd139.step / bd139.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: STMicroelectronics datasheet (9 pp, sha256 9a72cdfa334700b8, retrieved 2026-08-17, tier: manufacturer)
  • Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF