The 2N2222 is a common NPN bipolar junction transistor (BJT) used for general purpose low-power amplifying or switching applications. It is designed for low to medium current, low power, medium voltage, and can operate at moderately high speeds. It was originally made in the TO-18 metal can as shown in the picture.
The 2N2222 is considered a very common transistor, and is used as an exemplar of an NPN transistor. It is frequently used as a small-signal transistor, and it remains a small general purpose transistor of enduring popularity.
The JEDEC registration of a device number ensures particular rated values will be met by all parts offered under that number. JEDEC registered parameters include outline dimensions, small-signal current gain, transition frequency, maximum values for voltage withstand, current rating, power dissipation and temperature rating, and others, measured under standard test conditions. Other part numbers will have different parameters. The exact specifications depend on the manufacturer, case type, and variation. Therefore, it is important to refer to the datasheet for the exact part number and manufacturer.
|40 V||800 mA||500 mW/1.8 W||300 MHz|
All variations have a beta or current gain (hFE) of at least 100 in optimal conditions. It is used in a variety of analog amplification and switching applications.
Other NPN switching transistors
Replacements for the 2N2222 are commonly available now in the cheaper TO-92 packaging, where it is known as the PN2222 or P2N2222, which has similar specifications except for the lower maximum collector current. The P2N2222 has a different order of pins than the metal case 2N2222, with its emitter and collector connections switched; other plastic-case transistors also have different pinouts.
Single transistors are also available in several different surface mount packages, and a number of manufacturers market surface mount packages that incorporate several 2N2222-type transistors in one package as an array of transistors. The general specifications of the various variants are similar, with the biggest difference being the maximum allowable current and power dissipation.
The BC548 is a low voltage, low current, general-purpose switching transistor in a TO-92 package.
The 2N3904 is an NPN transistor that can only switch one-third the current of the 2N2222 but has otherwise similar characteristics. The 2N3904 exhibits its forward gain (beta) peak at a lower current than the 2N2222, and is useful in amplifier applications with reduced Ic, e.g., (gain peak at 10 mA for the 2N3904 but 150 mA for the 2N2222).
The 2N2219 is very similar with higher power dissipation rating.
- Dan O'Sullivan, Tom Igoe; "Physical Computing"; Cengage Learning; pp.19; 2004; ISBN 1-59200-346-X
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- Rudolf F. Graf and William Sheets (2001). Build your own low-power transmitters: projects for the electronics experimenter. Newnes. p. 14. ISBN 978-0-7506-7244-3.
The 2N2222, 2N2905, and 2N3055 devices, for example, which date back to the 1960s but have been improved, are still useful in new designs and are still popular for experimenters.
- Ed Da Silva (2001). High frequency and microwave engineering. Newnes. p. 263. ISBN 978-0-7506-5046-5.
Typical examples are the well known NPN and PNP industrial and military types, 2N2222 and 2N2907, which have been used for over four decades and are still being used in many designs.
- Jack Ward. "THE DEVELOPMENT OF THE 2N2222: The Most Successful and Widely Used Transistor Ever Developed!". The Transistor Museum. Archived from the original on 14 April 2011. Retrieved 26 March 2011.
Since its initial product launch by Motorola at the 1962 IRE Convention, the 2N2222 has become the most widely used and universally recognized transistor of all time. Billions of units have been manufactured over the past 45 years and there is continuing high volume annual production.
- http://www.semiconductormuseum.com/Transistors/Motorola/Haenichen/Haenichen_Page11.htm Haenichen oral history retrieved from the Semiconductor Museum 2011 May 13
- The Transistor and Diode Data Book for Design Engineers, Texas Instruments Incorporated, no date, TI publication number CC413 71242-73-CSS, page 4-93
- http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00003223.pdf Datasheet accessed 2013-10-26
- http://www.fairchildsemi.com/ds/PN/PN2222.pdf Retrieved 3 June 2012
- Dave Hrynkiw and Mark W. Tilden (2002). Junkbots, bugbots, and bots on wheels: building simple robots with BEAM technology. McGraw-Hill Professional. p. 44. ISBN 978-0-07-222601-0.
Learn to keep an eye open for the following transistors, as they're among the most useful, inexpensive, and popular types: PN2222/PN2907 These are general-purpose NPN/PNP transistors that can drive some good amounts of power. They're listed together because they're complementary transistors.