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BD135 NPN Power Transistor

Public Made by Adom

by adom

NPN medium-power transistor, 45 V / 1.5 A, in TO-126 for audio and driver stages.

transistorbjtnpnmedium-powerto-126st
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Contents

README

markdown

BD135

STMicroelectronics · Bipolar Transistor (BJT) · TO-126

The BD135 is an NPN medium-power transistor rated for 45 V and 1.5 A continuous collector current in a TO-126 package. It is the lower-voltage member of the BD135/137/139 NPN series, used in audio driver and output stages, discrete regulators, and medium-power switching.

Pinout

Pin Name Type Function
1 E passive Emitter. Common-emitter reference for the NPN device. VEBO max = 5 V; typically tied to the low-side rail or output node depending on topology.
2 C passive Collector. Electrically connected to the metal mounting tab. VCBO max = 45 V, VCEO max = 45 V, IC max = 1.5 A continuous (3 A peak). Thermal path to case: Rthj-case = 10 °C/W.
3 B input Base. Controls collector current via base-emitter forward bias. VBE(on) ≈ 1 V at IC = 0.5 A; VEBO absolute max = 5 V; IB max = 0.5 A.

Key specifications

Parameter Value
Type NPN medium-power transistor
Collector-emitter voltage (VCEO) 45 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

  • BD135
  • BD135-16

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-base voltage VCBO 45 V IE = 0 3
Collector-emitter voltage VCEO 45 V IB = 0 3
Emitter-base voltage 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
Collector cut-off current (NPN) ICBO 0.1 µA VCB = 30 V 4
Collector cut-off current (NPN) ICBO 10 µA VCB = 30 V, TC = 125 °C 4
Emitter cut-off current (NPN) IEBO 10 µA VEB = 5 V 4
Collector-emitter sustaining voltage (NPN, BD135) VCEO(sus) 45 V IC = 30 mA 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 40 250 IC = 150 mA, VCE = 2 V 4

CAD (KiCad official)

  • Symbol: bd135.kicad_sym
  • Footprint: bd135.kicad_mod
  • 3D model: TO-126 body from KiCad Package_TO_SOT_THT/TO-126-3_Vertical.
  • 3D model files: bd135-etched.step / bd135-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); bd135.step / bd135.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