Editing Transistor (section)

==Device identification==
Three major identification standards are used for designating transistor devices. In each, the alphanumeric prefix provides clues to the type of the device.

===Joint Electron Device Engineering Council (JEDEC)===
The [[JEDEC]] part numbering scheme evolved in the 1960s in the United States. The JEDEC ''EIA-370'' transistor device numbers usually start with ''2N'', indicating a three-terminal device.<ref>{{Cite web| title = Type Registration, Data Sheets| access-date = March 7, 2025| url = https://www.jedec.org/standards-documents/type-registration-data-sheets |publisher=JEDEC}}</ref> Dual-gate [[field-effect transistor]]s are four-terminal devices, and begin with 3N. The prefix is followed by a two-, three- or four-digit number with no significance as to device properties, although early devices with low numbers tend to be germanium devices. For example, [[2N3055]] is a silicon n–p–n power transistor, 2N1301 is a p–n–p germanium switching transistor. A letter suffix, such as A, is sometimes used to indicate a newer variant, but rarely gain groupings.

{|class="wikitable"
|+ JEDEC prefix table
|-
! Prefix !! Type and usage
|-
|1N || two-terminal device, such as diodes
|-
|2N || three-terminal device, such as transistors or single-gate [[field-effect transistor]]s
|-
|3N || four-terminal device, such as dual-gate field-effect transistors
|}

===Japanese Industrial Standard (JIS)===
In Japan, the [[JIS semiconductor designation]] (|JIS-C-7012), labels transistor devices starting with ''2S'',<ref>{{cite web |url=http://www.clivetec.0catch.com/Transistors.htm#JIS |title=Transistor Data |publisher=Clivetec.0catch.com |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160426190413/http://www.clivetec.0catch.com/Transistors.htm#JIS |archive-date=April 26, 2016 }}</ref> e.g., 2SD965, but sometimes the 2S prefix is not marked on the package–a 2SD965 might only be marked ''D965'' and a 2SC1815 might be listed by a supplier as simply ''C1815''. This series sometimes has suffixes, such as R, O, BL, standing for red, orange, blue, etc., to denote variants, such as tighter ''h''<sub>FE</sub> (gain) groupings.

{|class="wikitable"
|+ JIS transistor prefix table
|-
! Prefix !! Type and usage
|-
|2SA || high-frequency p–n–p BJT
|-
|2SB || audio-frequency p–n–p BJT
|-
|2SC || high-frequency n–p–n BJT
|-
|2SD || audio-frequency n–p–n BJT
|-
|2SJ || P-channel FET (both JFET and MOSFET)
|-
|2SK || N-channel FET (both JFET and MOSFET)
|}

===European Electronic Component Manufacturers Association (EECA)===
The European Electronic Component Manufacturers Association (EECA) uses a numbering scheme that was inherited from [[Pro Electron]] when it merged with EECA in 1983. This scheme begins with two letters: the first gives the semiconductor type (A for germanium, B for silicon, and C for materials like GaAs); the second letter denotes the intended use (A for diode, C for general-purpose transistor, etc.). A three-digit sequence number (or one letter and two digits, for industrial types) follows. With early devices this indicated the case type. Suffixes may be used, with a letter (e.g. C often means high ''h''<sub>FE</sub>, such as in: BC549C<ref>{{cite web |url=http://www.fairchildsemi.com/ds/BC/BC549.pdf |title=Datasheet for BC549, with A, B and C gain groupings |access-date=June 30, 2012 |website=Fairchild Semiconductor |url-status=live |archive-url=https://web.archive.org/web/20120407001013/http://www.fairchildsemi.com/ds/BC/BC549.pdf |archive-date=April 7, 2012 }}</ref>) or other codes may follow to show gain (e.g. BC327-25) or voltage rating (e.g. BUK854-800A<ref>{{cite web |url=http://www.datasheetcatalog.org/datasheet/philips/BUK854-800A.pdf |title=Datasheet for BUK854-800A (800volt IGBT) |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120415132635/http://www.datasheetcatalog.org/datasheet/philips/BUK854-800A.pdf |archive-date=April 15, 2012 }}</ref>). The more common prefixes are:

{|class="wikitable"
|+ EECA transistor prefix table
|-
! Prefix !! Type and usage !! Example !! Equivalent !! Reference
|-
|AC || [[Germanium]], small-signal [[Audio Frequency|AF]] transistor || AC126 || NTE102A || 
|-
|AD || Germanium, [[Audio Frequency|AF]] power transistor || AD133 || NTE179 || 
|-
|AF || Germanium, small-signal [[Radio Frequency|RF]] transistor || AF117 || NTE160 || 
|-
|AL || Germanium, [[Radio Frequency|RF]] power transistor || ALZ10 || NTE100 || 
|-
|AS || Germanium, switching transistor || ASY28 || NTE101 || 
|-
|AU || Germanium, power switching transistor || AU103 || NTE127 || 
|-
|BC || [[Silicon]], small-signal transistor ("general purpose") || BC548 || [[2N3904]] || [https://www.mccsemi.com/pdf/Products/2N3904(TO-92).pdf Datasheet]
|-
|BD || Silicon, power transistor || BD139 || NTE375 || [http://www.fairchildsemi.com/ds/BD/BD135.pdf Datasheet]
|-
|BF || Silicon, [[Radio Frequency|RF]] (high frequency) [[BJT]] or [[FET]] || BF245 || NTE133 || [http://www.onsemi.com/pub_link/Collateral/BF245A-D.PDF Datasheet]
|-
|BS || Silicon, switching transistor (BJT or [[MOSFET]]) || [[BS170]] || [[2N7000]] || [http://www.fairchildsemi.com/ds/BS/BS170.pdf Datasheet]
|-
|BL || Silicon, high frequency, high power (for transmitters) || BLW60 || NTE325 || [http://www.datasheetcatalog.org/datasheet/philips/BLW60.pdf Datasheet]
|-
|BU || Silicon, high voltage (for [[cathode-ray tube|CRT]] horizontal deflection circuits) || BU2520A || NTE2354 || [http://www.datasheetcatalog.org/datasheet/philips/BU2520A.pdf Datasheet]
|-
|CF || [[Gallium arsenide]], small-signal [[microwave]] transistor ([[MESFET]])&nbsp;|| CF739 || — || [https://web.archive.org/web/20150109012745/http://www.kesun.com/pdf/rf%20transistor/CF739.pdf Datasheet]
|-
|CL || Gallium arsenide, [[microwave]] power transistor ([[Field-effect transistor|FET]]) || CLY10 || — || [http://www.datasheetcatalog.org/datasheet/siemens/CLY10.pdf Datasheet]
|}

===Proprietary===
Manufacturers of devices may have their proprietary numbering system, for example [[CK722]]. Since devices are [[Second source|second-sourced]], a manufacturer's prefix (like MPF in MPF102, which originally would denote a [[Motorola]] [[FET]]) now is an unreliable indicator of who made the device. Some proprietary naming schemes adopt parts of other naming schemes, for example, a PN2222A is a (possibly [[Fairchild Semiconductor]]) 2N2222A in a plastic case (but a PN108 is a plastic version of a BC108, not a 2N108, while the PN100 is unrelated to other xx100 devices).

Military part numbers sometimes are assigned their codes, such as the [[UK CV series|British Military CV Naming System]].

Manufacturers buying large numbers of similar parts may have them supplied with ''house numbers'', identifying a particular purchasing specification and not necessarily a device with a standardized registered number. For example, an HP part 1854,0053 is a (JEDEC) 2N2218 transistor<ref>{{cite web |url=http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=27258 |title=Richard Freeman's HP Part numbers Crossreference |publisher=Hpmuseum.org |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120605183505/http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=27258 |archive-date=June 5, 2012 }}</ref><ref>{{cite web |url=http://www.sphere.bc.ca/test/hp-parts/300-hpxref.pdf |title=Transistor–Diode Cross Reference – H.P. Part Numbers to JEDEC (pdf) |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160508135527/http://www.sphere.bc.ca/test/hp-parts/300-hpxref.pdf |archive-date=May 8, 2016 }}</ref> which is also assigned the CV number: CV7763<ref>{{cite web |url=http://www.qsl.net/g8yoa/cv_table.html |title=CV Device Cross-reference by Andy Lake |publisher=Qsl.net |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120121111531/http://www.qsl.net/g8yoa/cv_table.html |archive-date=January 21, 2012 }}</ref>

===Naming problems===
With so many independent naming schemes, and the abbreviation of part numbers when printed on the devices, ambiguity sometimes occurs. For example, two different devices may be marked J176 (one the J176 low-power [[JFET]], the other the higher-powered [[MOSFET]] 2SJ176).

As older through-hole transistors are given surface-mount packaged counterparts, they tend to be assigned many different part numbers because manufacturers have their systems to cope with the variety in [[pinout]] arrangements and options for dual or matched n–p–n + p–n–p devices in one pack. So even when the original device (such as a 2N3904) may have been assigned by a standards authority, and well known by engineers over the years, the new versions are far from standardized in their naming.