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2N3055 NPN Power Transistor

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by Ray

Classic NPN power transistor, 60 V / 15 A, in a metal TO-3 package.

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2N3055

STMicroelectronics · Bipolar Transistor (BJT) · TO-3

The 2N3055 is a classic NPN power transistor rated for 60 V and 15 A continuous collector current in a metal TO-3 package. It has been a standard pass transistor in linear power supplies and an output device in audio amplifiers for decades. The TO-3 case is the collector, with base and emitter on the two pins.

Pinout

Pin Name Type Function
1 B input Base of NPN power transistor. Drives collector current via hFE (typ. 20-70 at IC = 4 A, VCE = 4 V). VBE ≈ 1.8 V at IC = 4 A. Absolute max IB = 7 A, VEBO = 7 V.
2 E passive Emitter of NPN power transistor. Common return for base-drive and collector current. For NPN 2N3055 normally tied to circuit ground / lower-voltage rail.
3 C passive Collector of NPN power transistor, electrically connected to the TO-3 metal case/mounting tab for heat-sinking. Rated VCBO = 100 V, VCEO = 60 V, IC = 15 A. Must be isolated from grounded heatsinks with a mica/insulator pad.

Key specifications

Parameter Value
Type NPN power transistor
Collector-emitter voltage (VCEO) 60 V
Collector current (IC) 15 A continuous
DC current gain (hFE) 20 to 70 at 4 A
Transition frequency (fT) 2.5 MHz
Power dissipation 115 W
Package TO-3 (case = collector)
Operating temperature -65 C to 200 C

Ordering variants

  • 2N3055

CAD (KiCad official)

  • Symbol: 2n3055.kicad_sym
  • Footprint: 2n3055.kicad_mod
  • 3D model: Metal TO-3 body from KiCad Package_TO_SOT_THT/TO-3.

Provenance

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

  • Datasheet: STMicroelectronics datasheet (7 pp, sha256 c957a8b217de71e5, 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