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Why is it so? The basic 74 series, the 4000, are such poor ICs compared to the newest families (by the 74: AUC, AUP, ALVC...), which only have advantages over the oldest one: lower power consumption, lower propagation delay...

LorenzoDonati4Ukraine-OnStrike
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Jean-Paul
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    How do you measure the "popularity"? – Eugene Sh. Nov 02 '17 at 15:42
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    I think when somebody says 7400, they really mean 74xx00 - use whatever logic family makes sense. Also, in most cases where discrete logic is used, performances is not really all that important. – alex.forencich Nov 02 '17 at 15:44
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    Cost, availability, multiple manufacturers, simplicity.. are all factors, but I'd argue they are not really that popular any more for new designs. They are still readily available though because they are still used everywhere in older equipment that is still manufactured. – Trevor_G Nov 02 '17 at 15:48
  • I measured popularity" in fact by their availability. The 74AUC are much harder to find and there's only a few distributors that sell them. – Jean-Paul Nov 02 '17 at 15:53
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    @Jean-Paul that is not unusual. New families are usually developed by a single vendor. The competition then has to either wait for the patent time to expire before they can make them. or make them under license. Either way there is a significant delay. – Trevor_G Nov 02 '17 at 15:55
  • The oldest digital ICs are less inclined to oscillate, thus produce better results as the students struggle with whiteboards. – analogsystemsrf Nov 03 '17 at 05:23

4 Answers4

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Why do you think TTL 74/54 series are popular? They are a relic of the past now (unless you have to maintain old hardware).

Metal gate CMOS 4000 series is also somewhat obsolete, but it has some advantage in some specialized digital application where its wide supply range (up to 15V at least) is convenient. Of course it's slow and power hungry, compared to newer CMOS families.

74HC/HCT is mainstream because it is mature and stable (but it's losing terrain).

The other, faster, families are used only if you really need their speed. A faster digital device is not necessarily an advantage in a circuit that doesn't need that speed.

If you are a student, I suspect that your intuition is skewed because many high-school labs (and even university labs) purchased tons of TTL (and CMOS 4000) chips and many teachers love beating a dead horse (sadly).

LorenzoDonati4Ukraine-OnStrike
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    +1 for dead horses, and the bucket of 741s and 555s is right next to the 7400s. – Trevor_G Nov 02 '17 at 15:52
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    @Trevor Yep! I'd save the 555 just for the nice internal design, which is didactically useful. But the 741, BURN IT! I still have colleagues that place orders for 741s even if they cost much more and they have worse specs than old dinosaurs like TL081s or LM358s! (BTW, I'm a teacher in an high school and I banned TTLs and 741s from my lab lessons ). – LorenzoDonati4Ukraine-OnStrike Nov 02 '17 at 15:58
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    :) good man.... – Trevor_G Nov 02 '17 at 16:04
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    While I agree that there are too many students that can only think about a 741 (because their teachers just used them), its simplicity makes them useful, especially when you must analyze their internal circuitry. Furthermore it's a good example of a bad operational. I mean, it brilliantly shows (with no effort!) all the issues an OP amp can have: high input current, high offset voltage, small input and output voltage range, low bandwidth, awful slewrate, etc. With many cheaper OA, the Ibias is so low that you need giga or teraohom resistors to show an appreciable effect! – next-hack Nov 02 '17 at 16:20
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    Still I agree. The next lesson, after the issue of a 741, should be the comparison against a much better performing and cheaper modern OA. – next-hack Nov 02 '17 at 16:22
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    @next-hack I love this expression of yours, man: *"it's a good example of a bad operational."*. They should write it in bold in the caption of its schematic that appears in lots of textbooks! :-) – LorenzoDonati4Ukraine-OnStrike Nov 02 '17 at 17:10
  • @Trevor_G What do you use instead of the 555? (Or are you just talking about the original 555 rather than the NE555/SE555/...?) – user253751 Jan 18 '18 at 05:08
  • @immibis I still use 555s now and again. But mostly I do MCU stuff so don't need external timers. – Trevor_G Jan 18 '18 at 12:24
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5 V logic was "standard" for many years, and there are still many systems and devices out there that need 5 V levels for their interfaces. If you're working with one of them, you need a logic family compatible with 5 V. Maybe not 7400 or 4000 series, but something like ALS or ACT.

Some systems even need higher voltage levels, such as 12 V. In these cases you might still want to use 4000 series logic.

Older families also have the advantage of being low cost and multi-sourced.

The Photon
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Cost, availability, multiple manufacturers, simplicity.. are all factors, but I'd argue they are not really that popular any more for new designs. They are still readily available though because they are still used everywhere in older equipment that is still manufactured.

But even today, sometimes it's just quicker and cheaper to plop on a simple NAND gate into a circuit rather than the alternative.

There is something to be said for the basic families though. They are after all foundational to all the higher order parts. You need a decent knowledge of them to really understand the rest so they definitely have their place.

Trevor_G
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Those "fancy" SSI/MSI technologies were developed at the tail end of the heyday of the wide use of SSI/MSI in high-volume commercial products, and were never manufactured in any great volumes. They were not generally incorporated into new equipment designs at the time, because of proprietary and single-source issues.

Microcontrollers, CPLDs, FPGAs and ASICs are the mainstream technologies used commercially today. Only hobbyists are still using SSI/MSI for design, and it is only the older technologies that were manufactured in high volumes (and are still manufactured for older equipment that is still being manufactured) that are generally available to them.

There are a few niche products that are used in modern design, such as the "single gate" logic that's available in SOT-23 packages, but again, because of the packaging, these are not popular with hobbyists.

Dave Tweed
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    "Only hobbyists are still using SSI/MSI for design" That brush might be a bit wide. There is still the occasional need to embed simple logic into some interface circuitry where using a plain old quad NAND will do and is less hassle than a programmed part. – Trevor_G Nov 02 '17 at 16:09
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    If these parts were only being made in the volumes required for hobbyists, I doubt they'd be priced under $0.10 each. – The Photon Nov 02 '17 at 16:10
  • @Trevor: See my third paragraph. – Dave Tweed Nov 02 '17 at 16:15
  • @ThePhoton: They were originally made in high volumes for commercial use, which drove the price down. They are still made for commercial use in older designs that are still being manufactured at low cost, and so are still available to hobbyists as well. However, prices *are* rising. – Dave Tweed Nov 02 '17 at 16:18
  • Yup for a single gate those are great. Not so cheap though... based on a cursory look at DIgikey – Trevor_G Nov 02 '17 at 16:19