# When were 3-pin voltage regulators introduced?

I can't seem to find this answer anywhere, i'll feel pretty dumb if someone is able to find it doing a quick google search. But.... I've had not luck. When were the first 3 pin voltage regulator ICs introduced?

• You should read up on some of the personalities in the industry: en.wikipedia.org/wiki/Bob_Widlar – Daniel Sep 26 '15 at 20:06
• When you say "introduced", do you mean "invented" or "marketed"? – Dave Tweed Sep 27 '15 at 1:31
• Alas this is still an open question. Both answers include the keyword term "probably". There are surprisingly no good sources on this. You'd think that Lojek's History of Semiconductor Engineering would cover it, but it doesn't. It does discuss the LM100 though. – Fizz Oct 10 '15 at 21:19
• By introduced I originally meant "invented," but I'd be interested to know when VRs were first marketed too – mosfet386 Oct 10 '15 at 23:57

Bob Widlar designed the first monolithic IC linear regulator, the µA723 for Fairchild Semiconductor in 1967, and later designed the LM100 for National Semiconductor.

This is the same guy who designed the first monolithic IC op-amp, the µA702, also for Fairchild.

Sadly, you're not going to find many online references to these things, since they're all long-obsolete, replaced by jellybeans nearly as ancient.

Now, the 723 isn't a three-terminal regulator. It's adjustable and more complicated to use than the later LM117/317, which essentially replaced it. The first monolithic three-terminal fixed regulator is probably the LM109/309, released in 1969.

• According to Lojek's book (see my comment under the question) the LM100 was the first monolithic regulator; also according to psma.com/sites/default/files/… it preceded the uA723. According to Lojek, Widlar had left Fairchild in 1965. The Wikipedia page (from which you probably got this info) cites a book by Harrison. But that book makes no mention of the 723! – Fizz Oct 10 '15 at 21:28

The first popular 3-terminal regulator was the 78XX series, introduced, if memory serves, by Fairchild as the $\mu$A78XX series ca. 1970. You can find the series listed in the 1973 Fairchild linear databook here, so no later than 1972-73. By '73 they had already introduced the $\mu$A78MXX series as well.

The LM317 (adjustable three terminal regulator) also hails from this approximate period.

Possibly preceding the 78xx series was the 3-terminal LM309, a Widlar design, in 1969 according to this. It was not as big a commercial success. I have my doubts about the thoroughness of the research that went into that reference- it does not mention Fairchild at all, and appears to be a National Semiconductor (RIP) centric view of history.

The 78xx series design is one of those that was done so well the first time and achieved such a wide acceptance that they are still used in vast quantities 40-45 years later, despite many competitive parts that perform better under one constraint or another.

• The LM prefix was used by National Semiconductor. (Perhaps TI will continue making new "LM" designated devices.) It was a common practice to clone a design, then either replace or augment the manufacturer-specific prefix on the part number. Therefore, I expect, purely from the part number, that the Fairchild part number is the clone, not the original. – Warren Young Sep 26 '15 at 20:55
• @WarrenYoung Do you have some evidence that shows the NS part preceded the Fairchild part? – Spehro Pefhany Sep 26 '15 at 21:17