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2N3055 NPN Transistor

A2N3055 transistor mounted on an aluminum heat sink. A mica insulator electrically isolates the transistor case from the heat sink.


The 2N3055 is a silicon NPN power transistor intended for general purpose applications. It was introduced in the early 1960s by RCA using a hometaxial power transistor process, transitioned to an epitaxial base in the mid-1970s. Its numbering follows the JEDEC standard.It is a transistor type of enduring popularity. It had 2 holse in the side flanges so it could be screwed in to a mica, epoxy, rubber or plastic insulator and then a metal heat sink.


The exact performance characteristics depend on the manufacturer and date; before the move to the epitaxial base version in the mid-1970s the fT could be as low as 0.8 MHz, for example.

Packaged in a TO-3 case style, it is a 15 amp, 60 volt, 115 watt power transistor with a β (forward current gain) of 20 to 70 at a collector current of 4 A (this may be 100 to 200 when testing using a multimeter). It often has a transition frequency of around 3.0 MHz and 6 MHz is typical for the 2N3055A; at this frequency the calculated current gain (beta) drops to 1, indicating the transistor can no longer provide useful amplification in common emitter configuration. The frequency at which gain begins to drop off may be much lower, see below.

2N3055 silicon NPN power transistor.
Category. Statistic.
Designed in. Early 1960s.
Made in. Early 1960s.
Transistors per chip. 1.
Power supply. 20 volts to 100 volts.
Still in use. Yes.
Nationality. American.


manufacturer Date VCEO VCBO VCER (100 ohms) IC IB PD @ TC=25 deg. hfe (pulsed test) fT
RCA 1967 60 VCEO(sus) 100 VCBO 70 VCER(sus) 15A 7A 115W 20-70 (at IC = 4Apulsed) not given
ON-Semiconductor 2005[6] 60 VCEO 100 VCBO 70 VCER 15A (continuous) 7A 115W 20-70 (at IC = 4A) 2.5 MHz

Related devicesEdit

PowerTransistor 2N3055 1

A 2N3055 transistor's internals. Author: Rolf Süssbrich Rsuessrb.

Toshiba 2n3055 transistor

2N3055 transistors have several applications in power circuits, including inverters and voltage regulators. Author: Mataresephotos.

Tesla KD503 transistor

A Tesla KD503 transistor. Author: Peter.shaman.

Variants with higher voltage ratings (e.g. 2N3055HV, with a 100Vceo rating), different case material or type (e.g. steel, aluminium, or plastic with metal tab), and other variations exist, in addition to the minor variations in ratings (such as a power dissipation of 115 or 117 Watts) between 2N3055-marked devices from various manufacturers since RCA's original.

  1. An MJ2955 ( PNP transistor|PNP ), which is also manufactured using the epitaxial process today, is a complementary transistor to the 2N3055.
  2. In the sixties and early seventies, Philips produced similar devices encapsulated in TO-3 packages under the reference BDY20 (described as being for "hifi" purposes) and BDY38 (although the BDY38 has lower voltage ratings than the 2N3055).
  3. A TO-3 P (plastic case) version of the 2N3055 and its complementary device MJ2955 are available as the TIP3055 and TIP2955 respectively, with slightly reduced power dissipation ratings.
  4. The 10 Amp (15 Amp peak), 80 Watt TIP33 (NPN) and TIP34 (NPN) are plastic-cased transistors with somewhat similar characteristics to the 2N3055 and MJ2955 respectively, and available in variants with 40/60/80/100 Vceo breakdown voltage ratings.
  5. The 2N3773, with a TO-3 case has slightly lower gain but significantly higher maximum ratings (150W, 140Vceo, 16 Amps).
  6. The 2N3054 is a much lower power version of the 2N3055, rated at 25 W, 55 V and 4 A, but became almost obsolete about the late 1980s when many TO-66 devices were withdrawn from mainstream manufacturers's lists. In many cases a TO-220 packaged version, such as MJE3055T, can be used instead of the 2N3054 as well as in some 2N3055 applications.
  7. KD503 is a higher power equivalent used in Eastern Bloc countries, and is intended for general purpose applications. It was produced exclusively by the Czechoslovakian electronics company Tesla. KD503 are packaged in a TO-3 case style (called T41 by Tesla), it is a 20 ampere (amp), 80 volt , 150 watt power transistor. It has a Gain–bandwidth product with a transistors transition frequency of 2.0 MHz. The KD503 have higher power and higher current than 2n3055. They were used extensively in the former Eastern Bloc countries in audio power amplifier s made by Czechoslovakian Tesla and Polish Unitra.

Also seeEdit

  1. Transistors
  2. Transistor and IC packages


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