All the components I own have strange names, like a transistor called 2N2222 and a motor driver called L293D. When you see these kind of things writen down do you instantly know what it means or do you have to google it every time?

How much information is hidden in these codes or are they totally random?

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    \$\begingroup\$ I registered on this site just to make this comment. I had to smile at "...do you have to google it every time?" - I started playing with electronics about 35 years ago. The Internet was something that we'd never heard of (and was in its infancy at the time) and the only references I had were piles of paper catalogues and data sheets provided (mostly free of charge) by component manufacturers and suppliers. My friends and I were laughed at because we talked in part numbers. Don't get me wrong, I'm not making fun of your question - just remembering how things used to be. :) \$\endgroup\$ Sep 12, 2011 at 19:22
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    \$\begingroup\$ en.wikipedia.org/wiki/… \$\endgroup\$
    – endolith
    Jan 29, 2016 at 17:49

7 Answers 7


The prefix often has a specific meaning, but the numbering following the prefix often doesn't.

In general:

1N... = diodes
2N... = transistors

A... (2 letters + 3 digits) = germanium transistor, e.g. AF117
B... (idem) = silicon transistor, e.g BC847

For diodes like 1N400x the last digit is kind of counter to indicate the diodes belong to the same series:

1N4001: 50V
1N4002: 100V
1N4003: 200V
1N4004: 400V
1N4005: 600V
1N4006: 800V
1N4007: 1000V

The 1N4148 is a typical switching diode. For it's SMT counterpart manufacturers use the same number (4148), but with a different prefix: Fairchild calls it an LL4148, Rectron an MM4148.
On the other hand, the SMT version of the BC547 transistor is the BC847, so there they keep the prefix, but change the number. You try and find the logic in it.

IC manufacturers often release new devices with their own prefix, like "LT" for Linear Technology, or "LM" for National Semiconductor, so sometimes it refers directly to the name, but often it doesn't. When other manufacturers make compatible parts, however, they often stick to the same part number, so that prefix doesn't always tell you who the manufacturer is. A MAX809, for instance, is made by (at least) Maxim, On Semiconductor and NXP. "TIP" originally meant "Texas Instruments Power" but you'll also find a TIP110 transistor with Fairchild.

Like Matt says sometimes the number following the prefix refers to the device's function. He mentions the MAX232 as an EIA232 driver, and guess what the MAX485 is. FTDI's FT232R is also an EIA232 bridge. But those are really exceptions.

Sometimes the last digit refers to the number of opamps, for instance, in a device.

LF411 = single opamp
LF412 = dual LF411

I once asked a question about other than manufacturer's prefixes in IC type numbers, but there seems to be little systematical in it.


I used to work for a semiconductor chip company. While there we came out with a new chip and I was involved in the talks for what the part number should be. We requested that the part number was "CS100". Our reasoning was that we wanted our chip to show up first in an alphabetical list of chips the company sells. The request for this number was flatly denied. The reasoning was, "The part number is not long enough".

The point is: Manufacturer part numbers only make sense to the people who came up with them-- and then only barely. Any resemblance to sanity is purely coincidental.

While I've only worked for one semi manufacturer, my experience with other companies has shown that this is true for all companies. The bigger and older the company, the worse it is.


For ICs, it's whatever the manufacturer feels like doing. Older stuff, like the 74xxx series logic have names that meant something internal to the manufacturer, which in this case was TI. Nowadays with the proliferation of ICs and trademarks, you see more and more the manufacturer name or a registered trademark of the manufacturer added into the full part number. For example, all Microchip microcontrollers have their PIC tradename in their full product number, Maxim parts numbers tend to start with MAX, etc.

Other part numbers like the common 2Nxxxx for transistors and 1Nxxxx for diodes come from standardization attempts. The 2N and 1N types are Jedec(?) registered, which is why various different manufacturers make a 2N3906 transistor. Sometimes manufacturers will add a prefix or suffix to this, and sometimes they will use the bare Jedec number for their conforming part.

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    \$\begingroup\$ Surely you mean Maxim - Maxxim are a consulting company - you know, people who are paid millions to tell you how to do what you've been doing for the past 30 years using different words to describe the same methods. \$\endgroup\$
    – Majenko
    Sep 12, 2011 at 17:49
  • \$\begingroup\$ @Majenko: fixed. \$\endgroup\$ Sep 12, 2011 at 18:17

You can often get the manufacturer from the prefix (AD for Analog Devices, LT for Linear etc), and often different families have similar numbers, so if you know one you may half recognize another.

Some are numbered after their function (MAX232 is an RS-232 driver)

Other than that it's totally at the whim of the manufacturer.

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    \$\begingroup\$ Actually, LM doesn't stand for Linear. Linear tends to use the LT (Linear Technologies) prefix. LM is a prefix used by National which stands for "linear monolithic" in their naming system. \$\endgroup\$ Sep 12, 2011 at 16:24
  • \$\begingroup\$ LT's what I meant. \$\endgroup\$
    – Majenko
    Sep 12, 2011 at 17:24

It is sort of as with words in everyday language. There might have been some sense in it for the hunter-gatherers that migrated from India to Europe eons ago. Some scholars devote their life to discovering such sense, but for most of us words are just (barely) pronounceable collections of letters, with a meaning that you just have to learn by heart.

Which we do. If you say 2N2222 I see a small metal can with three leads and I think "must be an old US circuit, otherwise they would use BC107/BC547 (European) or something more modern (2N3906?)". If you say L293D I see a small two-motor car whirling around, and I hope the built-in freewheel diodes will hold out, and the poor DIP package will not get too hot. Did the designer know that a motor will draw much more current when stalled? Maybe not, so I remove my foot from the path of the little Car.

  • \$\begingroup\$ "words are just... collections of letters... that you just have to learn by hart." With a spelling mistake in heart. Haha to the irony. Seriously though; I do appreciate your response :) \$\endgroup\$
    – Buh Buh
    Sep 14, 2011 at 9:11
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    \$\begingroup\$ Well, I challenge you to do better in Dutch :) \$\endgroup\$ Sep 14, 2011 at 17:09

The early semiconductors had the first letter always O this was for Britian . Example OC72 ,OC44 ,OC28. The O stood for Zero which was the heater voltage because semiconductors did not have filaments like vacuum tubes .Some Vacuum tube manufacturers had a prefix number to represent heater voltage .Examples 6AV6 12AX7 6AQ5 . This meant that those newfangled semiconductors could be easily incorperated in the existing Valve catalogs where gas filled regulator tubes that did not have filaments already started with O .A represented the first commercial semiconductor of Germanium.B represented Silicon which came later .So once apon a time there was a valiant attempt to make part numbers actually give some technical information.


Sometimes the part number is also just a marketing gimmick. When I worked at Linear Tech we released a cost reduced version of the LT1012 and called it the LT1097. Why 1097? Because the 1000 piece price of the part was 97 cents.


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