2n3055: all about the NPN bipolar transistor


There are many NPN transistors, such as 2N3045, etc., but one of the most well known and used is the 2N3055. This bipolar transistor is general purpose for power circuits. It is created by epitaxy processes to grow the semiconductor layers of which it is composed and then encapsulated in a metal package.

Certainly there is not a lot of information about this semiconductor device, since it is not very complex, but we tell you everything you need to know about it so you can add it in your future implementations of your most interesting circuits and projects.

Features and pinout of the 2n3055

Pinout 2N3055

Like other transistors, the 2N3055 has 3 connections for the emitter, base and collector. This has been discussed in other transistor articles. So, zero doubts about the pinout of this NPN transistor. The configuration is pin 1 for the base, to be used as a switch to let the current pass or not through the semiconductor, pin 2 is the emitter (normally connected to GND or ground), and the collector is really the TAB since there is no third pin (normally connected to the current).

The transistor 2n3055 can be used for medium power circuits, is safe, has a low saturation between collector-emitter voltage, the packaging is available lead-free, has a gain of more than 70 hFE for DC (linear) current, the maximum voltage that can handle or pass through the collector and emitter is 60v for DC, the same as the maximum current that can pass through the collector is 15A DC.

For the base, the limits are at 7v (base-emitter) and 7A DC in both cases. In the case of the voltage between the collector and the base it can reach 100v. If we consider the temperature at which it can operate, the range is between -65 to +200ºC. Therefore, it works at extreme temperatures without problem, something that not all electronic devices tolerate, especially if you look at the maximum temperature supported. By the way, as far as power dissipation is concerned, it reaches 115W, which is not insignificant…

Summary of characteristics:

  • Type: NPN
  • For medium power circuits
  • Gain 70 hFE
  • Collector-emitter 60v DC
  • Collector current 15 A DC
  • Base-emitter 7v
  • Base 7A
  • 100v collector-base
  • Operating temperature -65 to +200ºC
  • Power dissipation 115W
  • Metallic encapsulation


Equivalent and complementary

There are some equivalent transistors for 2n3055. You can use them as substitutes like 2n6673 and 2n6675. Other similar, but not equal, transistors are the MJ10023, BUX98 and BDW51. No problem you can use them in your circuits as an alternative, but you should read well the datasheets of all of them to see the possible differences, because they might not be the same in some cases and could generate problems in extreme cases.

If you are wondering about the complementary, i.e. the opposite, you can see the MJ2955. In this case, it is an almost brother transistor, identical in many of the characteristics described in the previous section, but it is a bipolar PNP instead of an NPN. Knowing the complements sometimes can help us a lot in our circuit compositions, that’s why we always include it in our posts.


Diagram 2N3055

To safely set up your circuits while maintaining the ranges supported by this device, you should see the datasheets of these devices. It can be made by many different manufacturers, and all of them have their own datasheets where there might be some differences. Freescale, STMicroelectronics, and Siemens are some of the better known manufacturers, but there are more.

For your future power switching circuits, amplifiers, PWM, regulators, signal amplifiers, and the long etc. of circuits that can be composed with the 2n3055, you can get the datasheets here:

  • Various datasheets from various manufacturers.
  • Since we have used ON Semiconductor 2n3055 for other electronic devices in the past, here is the datasheet of this company for the transistor in question…

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