Why is the 741 op amp still produced? - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: September 18, 2020, 10:49:46 pm
content: The 741 might have been a big deal in its day, but things have moved on. Nowadays we have a zillion different op amps to choose from, ranging from similar to vastly improved performance. I can’t remember the last time I saw one in a piece of equipment. And no one with a grip on reality designs them into new products. And even in the case of repairs for old equipment there would surely be modern substitutes available. And get this - I was looking at the TI 741 data sheet and it says the 741 “feature(s) improved performance over industry standards like the LM709.” The LM709 might indeed have been an industry standard fifty years ago but it’s a bit of a stretch to still refer to it as that. We’re in the age of GPUs with 28.3 *billion* transistors. It’s time the 741 was put to bed. It’s fine to read all about it from a historical point of view. That great, but I think school textbooks should stop using it as an example as if it were a mainstream device. But what to replace it with? Over to you.

author: Fixpoint
author_rank: Regular Contributor
timestamp: September 18, 2020, 11:12:20 pm
content: I don't see any relation between the fact that we have powerful GPUs and that a simple Op-amp is still produced. A GPU has nothing to do with what an Op-amp does.I don't know all the prices, but I guess the 741 is very cheap? If a company can save even 1 cent per unit in a production run, it will take the deal. After all, the game is not played in terms of performance but in terms of $. For me, the question would become interesting it it turns out that the 741 is actually more expensive than the competition!And so, I personally don't see any reason why a component should be replaced if it does the job and there is healthy demand, no matter how old it may be. But I'm no expert, maybe someone else here knows the details.

author: eti
author_rank: Super Contributor
timestamp: September 18, 2020, 11:22:40 pm
content: It's still produced because it's still being used.It's still produced because people want it.It's still produced because it's not discontinued.What answer are you seeking?Next up in open-ended forum question thread titles :"Why are <insert arbitrary choice> discrete ICs still being produced?"Just because new thing exists, doesn't disqualilfy old thing. NEW world needs to shut up and listen to OLD wisdom more, new world thinks it's "advanced" (yeah, okay then)

author: Circlotron
author_rank: Super Contributor
timestamp: September 18, 2020, 11:24:14 pm
content: Quote from: Fixpoint on September 18, 2020, 11:12:20 pmOf course a GPU has nothing to do with an op amp. It was just an example of how ic fabrication technology has moved on. And is there really still a healthy demand for 741s. Where are they all being used?

author: eti
author_rank: Super Contributor
timestamp: September 18, 2020, 11:26:55 pm
content: Quote from: Circlotron on September 18, 2020, 11:24:14 pmIdea: Write to all the major distributors & manufacturer(s) and ask them who their biggest customers/what their main applications are

author: Circlotron
author_rank: Super Contributor
timestamp: September 18, 2020, 11:27:32 pm
content: Quote from: eti on September 18, 2020, 11:22:40 pmYep! You got me there.

author: eti
author_rank: Super Contributor
timestamp: September 18, 2020, 11:29:24 pm
content: Quote from: Circlotron on September 18, 2020, 11:27:32 pmSorry, I couldn't resist

author: Wolfgang
author_rank: Super Contributor
timestamp: September 18, 2020, 11:30:12 pm
content: Quote from: Circlotron on September 18, 2020, 10:49:46 pmI stopped using it a decade or more ago. My jellybean is the LM358 now, also a methusalem. I dont think the LM741 is run high volumes and a lot of parts on the market are from storage area cleaning activities, but there is always a small spare part and retrofitting market where you want to stay as close to the original. Apart from that: No idea.

author: schmitt trigger
author_rank: Super Contributor
timestamp: September 18, 2020, 11:39:29 pm
content: Three trascendental questions;1- What is the true meaning of life?2- Does the universe have a beginning or an end?3- Who is still buying the 741 anyway?

author: bsfeechannel
author_rank: Super Contributor
timestamp: September 19, 2020, 12:07:58 am
content: Quote from: Circlotron on September 18, 2020, 10:49:46 pmWhere did you see that? I was browsing the 2018's revision of TI datasheet and didn't find any mention of LM709 at all.https://www.ti.com/lit/ds/slos094g/slos094g.pdfQuoteI bet my bottom dollar that the 741 of today is not the 741 of yore. It is just a modern op amp that meets or exceeds what is expected of a 741 op amp. Kind of an Edison screw light bulb with LEDs inside.

author: greenpossum
author_rank: Frequent Contributor
timestamp: September 19, 2020, 12:22:30 am
content: Quote from: Circlotron on September 18, 2020, 10:49:46 pmI don't know about you but I'm going back to thinking about what to have for lunch. Much more important question.

author: Circlotron
author_rank: Super Contributor
timestamp: September 19, 2020, 12:22:48 am
content: ^^ Okay. The first hit on google for me was for the 2015 data sheet revision.https://www.ti.com/lit/ds/symlink/lm741.pdf?ts=1600474832599&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FLM741%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Dasc-null-null-GPN_EN-cpc-pf-google-sa%2526utm_content%253DLM741%2526ds_k%253DLM741%2526DCM%253Dyes%2526gclid%253DEAIaIQobChMIrIrDpvnz6wIVxrWWCh0-MgUpEAAYASAAEgIO-_D_BwE%2526gclsrc%253Daw.ds

author: AlfBaz
author_rank: Super Contributor
timestamp: September 19, 2020, 12:29:15 am
content: 741?What I want to know is where are all my PUTs

author: rsjsouza
author_rank: Super Contributor
timestamp: September 19, 2020, 12:54:47 am
content: It is quite impossible to find the demand with manufacturers, but you could follow a distrubutor's stock for a while and get a grasp on the demand for the "mass market" - this would still tell very little about the big OEMs demands, but it is a start. If the disty has tens of thousands in stock, there is a reason why they are there.

author: bsfeechannel
author_rank: Super Contributor
timestamp: September 19, 2020, 01:29:37 am
content: Quote from: greenpossum on September 19, 2020, 12:22:30 amMaybe that's exactly what he's thinking.

author: bsfeechannel
author_rank: Super Contributor
timestamp: September 19, 2020, 01:46:53 am
content: The 741 is one of those products that established a standard in its category. It is like the 6L6 (introduced in 1936), or the 555, 1N4007, 1N4148 or the 7400 and 4000 series. I would not fret they're still around. I'd celebrate their longevity. They managed to survive even in face of "better" options.

author: magic
author_rank: Super Contributor
timestamp: September 19, 2020, 06:02:25 am
content: I have seen one ST UA741 in an analog soldering station. At least that's what was written on itThe station was some Atten IIRC.I'm not sure if they are even cheaper than LM358. I have seen fake 741 with 358 inside

author: james_s
author_rank: Super Contributor
timestamp: September 19, 2020, 06:07:21 am
content: Is the modern 741 still the same as the original 741? Or is it just a modern op-amp die that works in most applications that used a 741?

author: magic
author_rank: Super Contributor
timestamp: September 19, 2020, 06:33:42 am
content: Those from reputable manufacturers should be legit. I have never looked at 741, but you can see 5532, 358 and 4558 dice on Zeptobars and they still implement the original topology and ought to meet the original specs. Perhaps with some perks like more consistent offset or less flicker and popcorn noise.There is also some difference in die size. For example, modern 5532 from TI and ONS are noticably smaller than old-ass Signetics. In fact, Signetics die was too large to fit in SO8 so they offered it in wide SO16 with half of the pins unused, like LM10.On AliBay all bets are off. I have made a thread on that. Most chips that I tested were 358 or 4558. And, I mean, heavily die-shrunk clones of those, presumably made in China. Never tested if they meet the specs, power output and dissipation would be particularly interesting. Some people reported in the past that fake 5532 behave like a 4558 when watched on a scope, so there is that.

author: tszaboo
author_rank: Super Contributor
timestamp: September 19, 2020, 07:19:55 am
content: For example, if you certified a product, you dont want to re-certify it, because a part is no longer made. so the longer they make it the batter. Sometimes, it doesnt need to be the shiniest part in your circuit, and if the 741 works, you dont want to change it. Sometimes clueless people blindly copy schematics and they end up with 30 year old pars in their brand new device, and spend all the time in the world trying to fix it in software.It should just say NRND on the datasheet, and keep being produced.

author: temperance
author_rank: Super Contributor
timestamp: September 19, 2020, 10:29:20 am
content: Where I work we solely use the metal can version:https://www.mouser.be/ProductDetail/Texas-Instruments/LM741H-NOPB?qs=QbsRYf82W3G0muqZ4UBumg%3D%3DWe have them mounted by people wearing pure silk gloves to not have fingerprints on the shiny cans.For many things you don't need fancy op amps.Some applications where the LM741 or it's dual version are being used today:-Current sensing in welding equipment.-Amplifiers in intercom systems.-Rectifiers in audio metering circuits.-Switching power supplies auxiliary functions.-Military and aerospace.My favourites are the LM358 and the LM324.The real question is:how many pieces do you need? One or two or a few million and what are the requirements. An LM741 or even lower spec op amp will do just fine when all you are asked to do is drive s speaker in an intercom system. Some manufacturers even produce op amps far worse than an LM741 because the industry needs very low cost amplifiers. Examples can be found in the catalogue of NJR.Companies producing products in quantities usually have an engineer doing nothing else then counting µCents just for fun. This engineer will even look at the tolerance of a 0402 resistor. Just because 20 million 5% resistors are cheaper than a 1% resistor.

author: VK3DRB
author_rank: Super Contributor
timestamp: September 19, 2020, 11:21:21 am
content: Last time I used two 741's was 35 years ago when someone brought me an audiophile's pre-amplifier for me to fix. I cannot remember the brand, but it was high-end and overpriced. It has poorly designed PCB inside in that it used a discrete component layout with tightly packed vertically mounted PTH resistors all over the place with painted leads to prevent shorts. One channel worked, the other was distorted. Split rails. No schematic available either. I simply scraped the paint off the post-input equalising circuitry on the good channel and measured the gain using a 1kHz sinewave generator. I then laid two 8-pin DIP 741 op amps upside down and wired in a circuit around the pins and potted the 741's in epoxy. I did both channels because the owner might detect a quality difference between the two. The owner said it has never sounded so clear and he was delighted. Makes one wonder why they did use 741's in the first place, other than the "black magic" of using discrete components.Never needed to use a 741 since. I have used a lot of LM358's since.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 19, 2020, 11:28:45 am
content: A general note on technology -- older tech of some manner or another will almost never completely go away.Heh, hm, vacuum tubes, and horses for transportation, are probably two unusually good counterexamples. They still remain of course, but only at a tiny fraction of their peak glory, and mainly because of enthusiasts willing to bear the cost. It's fair that some stepping-stone technologies can be fully obsoleted, that's true, enthusiasts notwithstanding.But for everything that exists as a current basis for higher technology, it's never going away, no matter how integrated that higher technology is. Single BJTs and MOSFETs are still with us, as are op-amps and comparators, CD4000 and 74(LS)/HC logic, and all manner of MCUs from the 8051 (and even 4-bit machines, for that matter) to x86. Which, heh, x86 itself, I mean...(But not so much bit-serial machines, I think? They were great back in the days of serial memory -- rotating drum or delay line. Anyone know any current applications?)Meanwhile, we absolutely have CPUs with stacked Flash and DRAM dies, integrated switching regulators and all manner of peripherals and controllers, to realize insanely powerful SoCs in pocket-sized packages, with short bills of materials -- in a given product, they've displaced a whole host of other components, but they haven't displaced them elsewhere, and I suspect never will.And going further back, it's especially difficult to obsolete anything to do with handling of raw materials -- like ore mining and smelting will always be with us. The exact manner in which they are done, can vary -- compare electrowinning and refining of copper, to the blast furnace it replaced. And not that blast furnaces have gone away either, they're still king for iron as far as I know. Industrial forging is done in a manner and scale hard to imagine from antiquity, but it also strains the imagination to think of some kind of, say, 3D printing process that is able to produce a similar grain structure in as short a time. (But 3D printing also offers revolutionary opportunities in the design of intricate forms, otherwise-impossible cavities, and the use of difficult or otherwise impossible alloys and tempers, thanks to rapid fusion, directional solidification and powder metallurgy methods.)Tim

author: Circlotron
author_rank: Super Contributor
timestamp: September 19, 2020, 12:49:53 pm
content: Quote from: temperance link=topic=254270.msg3239684#msg3239684Yep, me too. One advantage the 741 does has over those two is the 741 has it's output transistors biased whereas the 358/324 has the bases of the output transistors simply strapped together. Good recipe for crossover distortion. You can of course add a pulldown resistor to the output, but yeah...

author: magic
author_rank: Super Contributor
timestamp: September 19, 2020, 02:53:52 pm
content: Then RC4558 is for you. Even seems to be cheaper on Mouser and it's a dual. Although this one has phase reversal AFAIK...

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2020, 04:18:50 pm
content: There are still a few circuits a round that are made for the 741. There is a lab supply kit (often from China) with TL081 OPs tortured with too much supply because the original circuit was made for the 741 that can stand a higher supply.For a slightly improved version of the LM358 with less cross over distortion, there is the MC33172 - faster and less distortion, but otherwise similar.The 741 was just so popular that there is still some demand and it is no magic in making them, even though they are not the cheapest to make and the supply current is rather high for the performance.

author: Rick Law
author_rank: Super Contributor
timestamp: September 19, 2020, 06:51:49 pm
content: There are posts about "right to repair" now and again. Right to repair means nothing if parts are not available. So from that perspective, the longer they can keep making that same something, the better it is for the consumer.

author: Rah_H
author_rank: Newbie
timestamp: September 19, 2020, 07:18:14 pm
content: 741 are used in analog function generators. I have a MCP SG1639A 3MHz Analog Function Generator/Counter which has multiple 741s in it complete with IC socket. Old school ICs are still used in a lot of Chinese lab equipment because they are proven to work and are profitable. It doesn't matter if the technology is 30 years old, it is going to serve someone's purpose. So why change it?

author: floobydust
author_rank: Super Contributor
timestamp: September 19, 2020, 08:55:57 pm
content: It's gotten ridiculous that semi manufacturers optimize one or two things, roll out a new part number. Do we really need 5,000 different op-amps and the hours spent looking at datasheets to find the best part- which ends up being massively overpriced kills the BOM cost, or has long lead-times.Why is a LM358 $0.15 but a better part over 10x the cost? Do they have more gold-pressed latinum inside?An op-amp that has true competition has a reasonable price. Multiple-sourced 741, 358, 4558 is also why they are still alive.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 19, 2020, 09:51:30 pm
content: One problem leading to so many OP variants is that they often behave different in the details. There are quite a few parameters to look at and not always is there a clear better or worse. There are cases when one wants some input bias current (especially a defined sign and order of magnitude). Also faster is not always better.So the problem is that there is usually no 100% replacement / upgrade. Even if it works in 99.9% of cases it can't replace the original. There are plenty of OP versions that are not really needed any more: e.g. TL082 if there are TL072 (tighter noise specs) at essentially the same price and sometimes even cheaper.With the serious distributors they even make a difference between the same part from different source (e.g. 741 or LM358 from several vendors with essentially identical specs).Usually one has a few personal favorites in the head / drawer, so one knows if they are sufficient. One may later change to a more suitable/specific OP (e.g. lower cost), but one may also skip that step. The 741 is likely still in some peoples favorites / known by hart list. So even if not the best part it is still used. The best 741 substitute is probably still a 741 from a different source.

author: schmitt trigger
author_rank: Super Contributor
timestamp: September 20, 2020, 03:48:20 pm
content: Quote from: bsfeechannel on September 19, 2020, 01:46:53 amAnd let’s not forget that ubiquitous double triode, the 12AX7/ ECC83.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 20, 2020, 06:17:08 pm
content: I haven't seen a 741 "in the wild" in a very long time, but I did see lots of 4580s and whatnot on sound cards until digital became the norm.I suspect a lot of "classic" opamps like the 741 and LM386 are still used in music production specifically for their less than perfect audio qualities.Quote from: Kleinstein on September 19, 2020, 09:51:30 pmThat was once done to sell the parts that fail to qualify as the superior version, but nowadays with much more mature processes, I suspect most of the "inferior" parts are simply remarked to meet demand.Quote from: schmitt trigger on September 20, 2020, 03:48:20 pmWe can thank the audiophiles for that. Of course, they're not really after better audio quality when they use tubes, they're after making it sound like the way they remembered it back in the day.

author: David Hess
author_rank: Super Contributor
timestamp: September 20, 2020, 09:02:52 pm
content: Quote from: Circlotron on September 18, 2020, 10:49:46 pmHow many of those parts have a maximum supply voltage of 44 volts and a maximum differential input voltage of 30 volts? These things make the 741 easy to use at higher supply voltages.There are parts with those characteristics which are significant improvements over the 741, but they are several times more expensive, and even they are 30+ years old.Things are even worse when you consider the equally old 301A which supports external compensation and clamping unlike anything modern.

author: David Hess
author_rank: Super Contributor
timestamp: September 20, 2020, 09:05:58 pm
content: Quote from: floobydust on September 19, 2020, 08:55:57 pmThe 358/324 were optimized from the start for small die size which is why dual and quad parts were even possible. Improved replacements for them like the LT1013/LT1014 are optimized for performance and are huge in comparison.

author: julian1
author_rank: Frequent Contributor
timestamp: September 21, 2020, 01:49:25 am
content: What I find odd, is that there are >8000 op-amp variations available, all trying to exploit vanishingly small and segmented market niches. But it's really hard to find common matched npn/pnp pairs (on the same substrate) in order to implement current mirrors, long tail pairs, differential amps - which are the building blocks of analog circuits and those op-amps. I only know a couple of inexpensive parts bcm846 bcm857, unless I completely fail at parameterized search.

author: David Hess
author_rank: Super Contributor
timestamp: September 21, 2020, 03:41:48 am
content: It would sure be nice to have transistors arrays built on the modern 36 volt complementary bipolar process used for rail-to-rail precision parts, high slew rate voltage feedback operational parts, and current feedback operational amplifiers. For a while after Linear Technology released resistor arrays based on their thin film resistor process, I hoped they would release transistor arrays but they never did, and they discontinued their LT1088 thermal RMS converter.THAT Corporation sells matched quad transistor arrays in both polarities intended for audio applications which might have acceptable availability, but they are not cheap.National used to make the LM389 which was an LM386 class audio amplifier plus three uncommitted NPN transistors which was a useful and inexpensive source for matched monolithic transistors.

author: EEVblog
author_rank: Unknown
timestamp: September 21, 2020, 04:37:33 am
content: Simple, it's a known quantity and industry standard used by countless engineers for generations.When you ask "why is it still used", think instead "what would replace it". Better yet, set up a poll and see what results you get, I guarantee there will not be a consensus on an answer.That non-consensus is why the 741 is still the jellybean opamp choice.

author: floobydust
author_rank: Super Contributor
timestamp: September 21, 2020, 05:36:39 am
content: Quote from: David Hess on September 20, 2020, 09:05:58 pmI think the main driver is op-amp cost. They can be a huge hit to your BOM costs.Linear Tech is top quality and extremely expensive. LT317AT is USD$5.00 and LM317T-DG $0.77 that's a monster difference.LT1013CN8 USD$5.75 16wk lead-time when it's out, I've had to wait that.LM358PE4 $0.36 and never out of stock. I don't see the silicon area as the cost multiplier of 16x although I'm not an expert on the process and die sizes. Sure the LT1013 eliminated the PNP O/P tranny and added a bunch of others to crank up the gain. Kudos to LT for having the balls to update the old dog op-amps. I'd pay double or triple the price but no more.

author: David Hess
author_rank: Super Contributor
timestamp: September 21, 2020, 08:50:55 am
content: Quote from: EEVblog on September 21, 2020, 04:37:33 amThe 741 also has better specifications than many similarly priced but modern parts, like its common mode rejection.Quote from: floobydust on September 21, 2020, 05:36:39 amThe LT1013 is second sourced from TI so has reached a reasonable price.In production quantities, real precision parts like the LT1097 are a deal.

author: SeanB
author_rank: Super Contributor
timestamp: September 21, 2020, 10:23:16 am
content: Biggest user is Aerospace, simply because the darn things are rugged, reasonably reliable, are available in rad hard versions, and also are the part that is certified for this application. gotten them and abused them, and they are rugged, even when using them with 44 volt power rails, so they would be able to output 30V peak to peak, replacing some dead OP20 amplifiers, though i did add the TO100 heatsinks to them to keep them cool, unlike the OP20's, which had cooked nicely.Yes for general purpose use at lower voltages there are better parts, but for industrial logic with not much required frequency wise, and with a truly big common mode range hard to beat, plus they will survive transients that would kill other opamps, simply because the die is so large.

author: rdl
author_rank: Super Contributor
timestamp: September 21, 2020, 02:59:45 pm
content: If you've spent hundreds or thousands of hours testing, possibly over several years, to qualify something, then you really don't want to have to do that again because some component is no longer available. This is true no matter what industry you work in or what type of product you make.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: September 21, 2020, 04:44:42 pm
content: I just bought 20 of them last week. Way overpriced at about 40 cents US each, but fast and free delivery and I didn't have to leave the house to go get them. They are marked like real ST UA741CN and look genuine on the outside. But I wouldn't know how to tell a fake except if it flat out didn't work, and my intended use case is very undemanding, I hope. I am still playing around with that Chaos Oscillator circuit from another thread. I first built it up with 2 358 chips but the original was done with 4 discrete single-chip opamps, not specified in the paper, but odds are they used 741.Also I have a bunch of vintage equipment, like my main bench power supply and an IEC signal generator, that has them scattered around in the circuitry in various places. I only had 2 remaining in my IC tin so I went ahead and ordered a handful to play with and for spares.

author: magic
author_rank: Super Contributor
timestamp: September 21, 2020, 05:34:51 pm
content: Quote from: alsetalokin4017 on September 21, 2020, 04:44:42 pmOne annoying sort of fakes are LM358 with false markings. Some are normal duals and likely to burn if you plug them into a single socket, others are rewired internally to work as singles. The latter can be spotted by having nothing connected to the offset null pins. A few people already scratched their heads over excessive bias current, noise or crossover distortion in what was supposed to be a TL07x or NE553x.

author: VooDust
author_rank: Regular Contributor
timestamp: September 21, 2020, 05:43:15 pm
content: Quote from: Circlotron on September 18, 2020, 10:49:46 pmYeah it would be great if they stopped writing these "what are the essential op-amps" type blog posts where the 741 ranks on top. I would have gladly paid 50 cents more and get something that works rail to rail, thank you. For beginners anyways.

author: peter-h
author_rank: Super Contributor
timestamp: September 21, 2020, 08:49:40 pm
content: One would not design-in a 741 today, or anytime since about 1975, but it would be wrong to say the LM358 (which I've been using since c. 1975) replaces the 741 because - for a start - the output voltage swing is very different.There are rail to rail (on both input and output) op-amps but they are quite expensive. I have just done a design which needs to achieve 16 bit DC precision and a lot of the op-amps cost around $2 each.As a general comment, the world has moved many years ago from generic (and cheap, multi sourced) parts to high performance (and expensive, single sourced) parts. A clever designer will use the former, and they still exist. A lazy designer will use the latter, and keeps firms like Linear Technology in business

author: Wolfgang
author_rank: Super Contributor
timestamp: September 21, 2020, 08:59:55 pm
content: Quote from: peter-h on September 21, 2020, 08:49:40 pmI would agree that the 358s/324s cannot replace the 741s in case crossover distortion is a big issue, but in other cases the advantages are obvious:- 2/4 instead of one in a single case- more current- negative rail included in input and output, thats often enough.- cheaper- slightly faster- lower voltage operation possible (>2.5V)So, 741 for repair/replace/legacy systems business - why not. New stuff ? Never.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: September 21, 2020, 09:26:00 pm
content: Let's just say that I made the mistake of using op-amps from Microchip. Once.

author: james_s
author_rank: Super Contributor
timestamp: September 21, 2020, 09:40:25 pm
content: Quote from: Tomorokoshi on September 21, 2020, 09:26:00 pmI've used them a few times, they worked fine, it was very non-critical applications though. Curious what problems you experienced?

author: coppice
author_rank: Super Contributor
timestamp: September 21, 2020, 10:00:41 pm
content: Quote from: Circlotron on September 18, 2020, 10:49:46 pmThe world needs a lot of simple glue chips to sit between the big chips. Time was when 2 input gates only came in packs of 4. These days you can buy a small pack with just one gate in it, responding to the common modern need for just a single gate here and there as glue between complex chips. Billions and billions of simple low performance op-amps are used each year. However, if you ask someone at TI to recommend a simple low performance cheap op-amp they'll probably recommend an LMV321, or an LMV324 is you need several amps. Note than the LM321 is about as old as the 741, but most people use the more flexible LMV321 derivative these days. Nobody recommends a 741 any more, but a lot are still used in equipment whose design hasn't changed for decades.

author: Zero999
author_rank: Super Contributor
timestamp: September 22, 2020, 09:58:59 am
content: Quote from: coppice on September 21, 2020, 10:00:41 pmHow is the LMV321 more flexible, than the old LM321? It has some advantages: lower power consumption, bias currents and a rail-to-rail output, but the fact it only works up to 5.5V, rather than 30V, severely limits its applications, making it inflexible compared to the old LM321.

author: coppice
author_rank: Super Contributor
timestamp: September 22, 2020, 10:14:08 am
content: Quote from: Zero999 on September 22, 2020, 09:58:59 amThe supply voltage limitation hardly limits it at all in practice. In most modern designs people aren't looking to operate from 32V. They are looking to get great results from a 3V to 5V supply. The LM321 says it operates from 3V to 32V, but at 3V its performance is terrible. The LMV321 is described as rail-to-rail, which is always a bogus description, but it gets reasonably close. One of the things you have to watch out for with the LMV32x is that they are generic part, available from many suppliers, but some are closer to rail-to-rail than others. If you want flexibility in sourcing parts you need to ensure your design can work with the worst of them.

author: free_electron
author_rank: Super Contributor
timestamp: September 22, 2020, 12:38:57 pm
content: Quote from: NiHaoMike on September 20, 2020, 06:17:08 pmlike when they were 30 years younger and their hearing was better than now ...

author: TimFox
author_rank: Super Contributor
timestamp: September 22, 2020, 12:45:42 pm
content: Everybody agrees that the music in the 1960s was better than what followed--probably because of the Allen-Bradley carbon composition resistors.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 22, 2020, 01:20:20 pm
content: Somewhat related to this:The Allwinner A10 (or was it the A13) is a now obsolete microprocessor.Olimex is an (apperently decent sized) customer of those chips, and they have customers who use them in industrial boards. I.E. Tested & verified, long term planning and such.On the Olimex website there is a long blog post about Alwinner re-starting the factory for those chips for a batch of 50.000 special delivery to Olimex.I do not know what the normal lifespan of a set of masks is. Did they dust of old masks for this, or just made new ones because they wear out after 50.000 chips?

author: coppice
author_rank: Super Contributor
timestamp: September 22, 2020, 02:17:57 pm
content: Quote from: Doctorandus_P on September 22, 2020, 01:20:20 pmOnly a very young and naive engineer, or an idiot, puts a semiconductor device into an industrial application without checking its life status..... unless its truly a one off project. Most industrial stuff stays in production for years, while most complex consumer parts appear and disappear at random, according to how well high volume purchases are going.50k parts is a very small run. The masks, processes, packing and test facilities are almost certainly still available. The device isn't that old.

author: TimFox
author_rank: Super Contributor
timestamp: September 22, 2020, 02:34:37 pm
content: When the analogous questions were asked in the Soviet Union in 1950, they appointed a commission to study the problem. See:https://www.cia.gov/library/readingroom/docs/CIA-RDP80-00809A000600330961-8.pdf

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 22, 2020, 04:35:06 pm
content: Quote from: coppice on September 22, 2020, 02:17:57 pmIt's very easy to be tempted by $5 (and less) LCD displays, and powerful (if perhaps buggy, but hey, we can fix that in software, right?..) CPUs, and so on, and just say "if it drops, we'll respin the product with the next closest thing, it'll befine"...It's no accident that there's an entire market built around extending the production lifetime of these products. Most of these sorts of things you'll find on Digi-Key and such, are targeted this way (as far as I know). You don't go on Alibaba to find some no-name LCD, you find the mature e.g. Newhaven Display, and yup, it costs four times as much, and often it's worth every penny.(Just spot checking a random part by Newhaven, I see 6-10 year estimated product lifetimes.)Tim

author: free_electron
author_rank: Super Contributor
timestamp: September 22, 2020, 05:19:51 pm
content: Quote from: Doctorandus_P on September 22, 2020, 01:20:20 pm50.000 is going to be one batch of wafers. ( 25 or so if they run 300mm wafers) , so this is peanuts. Masks can expose millions of wafers without issues. so no problem at all.

author: David Hess
author_rank: Super Contributor
timestamp: September 23, 2020, 02:01:32 am
content: Quote from: Wolfgang on September 21, 2020, 08:59:55 pmThat brings up *why* true dual 741s were so expensive and it was simply because the integrated 30 picofarad capacitor takes up a lot of space. The 358/324 design only requires a 5 picofarad compensation capacitor because it was designed with transconductance reduction of the first stage making it suitable for dual and quad parts. What you are asking for is the 1458 which is a 741 designed with transconductance reduction making it suitable for dual and quad parts.QuoteThat requires larger output transistors and increased power dissipation compromises precision. There were a lot of high voltage and high current parts based on the 741 design but they were ultimately not economical.QuoteSingle supply and rail-to-rail outputs are feasible but complicate the design and the extra area increases the cost.Single supply and rail-to-rail inputs exclude input bias current compensation. Rail-to-rail inputs compromise common mode rejection.The above implies that there should be high performance precision parts with rail-to-rail outputs, and there are.QuoteAnything which increases the area of the chip or increases the testing time also increases the production cost.QuoteThere are plenty of faster (3 MHz) 741 equivalents based on the PNP input MC4558 dual and RC4138 quad. They are not true 741s, having PNP inputs means that their input bias current is reversed, but they were intended to have 741 performance except for being faster.

author: schmitt trigger
author_rank: Super Contributor
timestamp: September 23, 2020, 02:02:21 am
content: Quote from: TimFox on September 22, 2020, 02:34:37 pmVery interesting report.Nevertheless the Soviet Union managed to design many wonderful tube types and build them in large quantities.

author: peter-h
author_rank: Super Contributor
timestamp: September 23, 2020, 08:49:58 am
content: I would say the proliferation of so many different parts is mainly due to chip makers trying to trap inexperienced designers (or ones working in large companies which already carry a diverse parts stock) into designing-in non-commodity parts.A chip maker like say LT makes 10x more from one of those than somebody else makes from a 358.Whereas if you are a designer working in your own business, you will do everything possible to avoid non commodity parts. That's what I have been doing since 1978

author: Zero999
author_rank: Super Contributor
timestamp: September 23, 2020, 09:45:03 am
content: Quote from: coppice on September 22, 2020, 10:14:08 amI don't get the obsession with using stupidly low voltages, for analogue. It increases noise and forces the use of more expensive, poorer performance components. More often than not, there's a >5V supply available to run the analogue section off, such as in an automotive application and there are still plenty of applications requiring >5V parts, such as high side current sensing. Granted, there are dedicated parts available to do this, but none so cheap as the old LM321 and a few resistors. Regarding 3V analogue, that's just silly and should only be done when there's no alternative. It's very rare there isn't a 5V supply to power an old LM321 off.

author: coppice
author_rank: Super Contributor
timestamp: September 23, 2020, 10:43:50 am
content: Quote from: Zero999 on September 23, 2020, 09:45:03 amThese days the vast majority of analogue circuitry is a signal conditioning adjunct to digital circuitry, and people want to run both from the same rail. Even in applications like automotive, there are higher voltage available, but they will need regulating. If you can regulate just once for both the analogue signal conditioning and the MCU you have a win. 5V rails are becoming rare, as all new MCUs run at lower voltages than that. If you are building things like amps, then using high voltages is not just better, its essential. However, this is now a small part of the total market.

author: Zero999
author_rank: Super Contributor
timestamp: September 23, 2020, 12:49:13 pm
content: Quote from: coppice on September 23, 2020, 10:43:50 amWhat are you talking about? 5V is pretty standard from USB/wall wart power supplies. True, it's often regulated down to 3.3V or whatever, but it's still available at the input.Regarding automotive applications: that sounds like bad/lazy design to me. The LM321 can work from an unregulated power supply, so no it doesn't need to be regulated. It just requires the usual anti-load dump transient protection, which you need anyway before the 5V/3V regulator. It can also tolerate its input voltages up to 32V, even when run from lower power supply voltages.

author: coppice
author_rank: Super Contributor
timestamp: September 23, 2020, 03:41:01 pm
content: Quote from: Zero999 on September 23, 2020, 12:49:13 pmWhat are you talking about? Most of the world's electronics doesn't run from a USB wall wart. 15 years ago many people complained when you offered them a part that could only work from 3V. If you were in a silicon vendor the sales people were endlessly asking for 5V tolerant parts from the designers. That has changed. Get with the times. Automotive seems to be the last bastion of 5V, but that is changing.Quote from: Zero999 on September 23, 2020, 12:49:13 pmHave you compared the price of an LM321 with an LMV321? Who wants to pay the price of a large geometry part that can tolerate high voltages, when most of your module is running from 3V or 5V anyway?

author: Zero999
author_rank: Super Contributor
timestamp: September 27, 2020, 10:33:03 am
content: Quote from: coppice on September 23, 2020, 03:41:01 pmUSB wall warts seem to be pretty universal.The LM321 is cheaper than the LMV321. There clearly isn't any more debate to be had. If you've got 5V, or higher available, use that and the LM321, rather than 3V and the LMV321.https://www.digikey.com/products/en/integrated-circuits-ics/linear-amplifiers-instrumentation-op-amps-buffer-amps/687?FV=-8%7C687&quantity=0&ColumnSort=1000011&page=1&k=LM321&pageSize=25&pkeyword=LM321https://www.digikey.com/products/en/integrated-circuits-ics/linear-amplifiers-instrumentation-op-amps-buffer-amps/687?FV=-8%7C687&quantity=0&ColumnSort=1000011&page=1&k=LMV321&pageSize=25&pkeyword=LMV321

author: coppice
author_rank: Super Contributor
timestamp: September 27, 2020, 10:42:27 am
content: Quote from: Zero999 on September 27, 2020, 10:33:03 amI find your use of Digikey as a measure of real prices hilarious.

author: Zero999
author_rank: Super Contributor
timestamp: September 27, 2020, 11:41:16 am
content: Quote from: coppice on September 27, 2020, 10:42:27 amThe LM321 is also cheaper than the LMV321 in Mouser and RS Components.

author: coppice
author_rank: Super Contributor
timestamp: September 27, 2020, 02:48:14 pm
content: Quote from: Zero999 on September 27, 2020, 11:41:16 amYour point is? These are all places that serve low volume customers where prices bear little relation to volume prices. One part may be only 2 times the volume price, while others can be 100 times the volume price. Not only do these places not give you a clue about volume prices, they don't even give you a clue about relative prices.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 27, 2020, 02:52:38 pm
content: The LM321 are an odd product: quite a few of the LM321 versions seem to be actually LM358 dies using only one half: the supply current is usually the same as both OPs from the LM358 and not halve (or only slightly more). There seem to be a few now with lower current (e.g. from ONS).For low voltage use (e.g. up to 5 V) there are quite a few affordable rail to rail CMOS OPs (e.g. MCP600x) - maybe not cheaper than the LM321, but below the 741.One can also have a faster and less crossover distortion OP otherwise similar to the LM358 (e.g. MC33171-4) - this one could replace the 741 in most cases.

author: Zero999
author_rank: Super Contributor
timestamp: September 27, 2020, 04:22:02 pm
content: Quote from: Kleinstein on September 27, 2020, 02:52:38 pmI've never used the LM321, just the LM358. If I only want one amplifier, I just disable the other. The only reason for the LM321 is to save board space.

author: bson
author_rank: Unknown
timestamp: September 27, 2020, 11:43:17 pm
content: It's pretty much the only single-channel DIP-8 op amp that can handle a 44V supply. Well, except the LF356 (JFET) and the LT1010. Cheap as dirt, too (unlike the LT part).

author: coppice
author_rank: Super Contributor
timestamp: September 27, 2020, 11:57:57 pm
content: Quote from: bson on September 27, 2020, 11:43:17 pmIt will be interesting to see what happens to these higher voltage parts as less and less fabs remain functional which can produce them. People do not seem to see enough market size to justify developing new high voltage parts right now, although I guess they will be forced to as the last ancient fabs close. Some people will always need high voltage operation.

author: james_s
author_rank: Super Contributor
timestamp: September 28, 2020, 04:08:16 am
content: Quote from: coppice on September 27, 2020, 11:57:57 pmWhat about fabs making HV parts like mosfet drivers, SMPS ICs and that sort of thing? Couldn't they make HV op amps? The market for things like motor drives and power supplies isn't going anywhere.

author: Zero999
author_rank: Super Contributor
timestamp: September 28, 2020, 07:53:43 am
content: Quote from: bson on September 27, 2020, 11:43:17 pmNot all '741s are rated to 44V. The LM741C is only rated to 36V maxium.The classic OP07 and NE5532 will withstand 44V, but are only specified to ±20V.Quote from: james_s on September 28, 2020, 04:08:16 amNot to mention high side current sensing.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 28, 2020, 09:11:55 am
content: There are still a few high voltage OPs available and even new one released, e.g. MCP6V51 is specified to 45 V, though not a direct 741 replacement but AZ and only smaller cases.At the lower cost end, when the LM358 and related are not an option (e.g. higher supply voltage, speed, cross over) the 741 is still a viable option, but there are alternatives besides the LM301.

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2020, 12:58:00 pm
content: Quote from: james_s on September 28, 2020, 04:08:16 amOf course there is a need for. and will always be, high voltage parts. However, with many of the fabs that make the ancient higher voltage parts reaching their end of life there are going to be some significant changes in the industry. Will the people scrapping ancient fabs replace them? Will new players take up the work? It will be interesting to see.

author: exe
author_rank: Unknown
timestamp: September 28, 2020, 01:06:00 pm
content: Why a new fab cannot produce an old part? (I can see why this is uneconomical == doesn't make sense on current market).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 28, 2020, 01:26:07 pm
content: For one, the part probably has to be redesigned, because all the characteristics are different.For another, no one's making the high voltage BJTs like the old way. A 10 or 20V part would be easy enough to do. But that's nowhere near the original spec.TLV2372 is probably an example of this, using a high voltage CMOS process (18V max). Though I don't know offhand if that's metal or poly gate HVCMOS -- there's poly HVCMOS, right?Which is not to say there aren't any fabs doing that sort of thing. Discrete BJTs aren't going away any time soon. I'm not sure why they couldn't simply run a different mask set there (and insert a couple more passes for doping as applicable, and metallization; of course, doping can't be done willy-nilly, that's a whole process refinement step). Perhaps access to the fabs is poor (who's making BJTs anymore? It's not all China now is it..?).There are plenty of HV processes, ranging from ~20V amps like the above example, to 50-60V regulators and switchers, to 600V+ gate drivers. Probably these are optimized for CMOS though, and BJTs are rough on a CMOS process. (Also, not that the 600V transistors in HVICs are necessarily any good -- they do actually exist, and the HVIC process isn't just a high side isolation thing, transistors are included and that's indeed how they couple signals to the high side -- but not much performance is needed for that, either.)I suppose LT (now ADI)'s internal fab is one of the most likely candidates; they've been making interesting BJT-based parts for ever. There aren't many ways you can make a buck regulator operate from 2-30V, but BJTs are a good one. Datasheets don't usually say much of anything about internal design or process, so it's not obvious from here how much they do that, but obviously it's what they're doing when they show an NPN switch on the block diagram.Going back to direct substitutes, there are plenty of >30V op-amps out there, some with quite impressive specs. I don't know how many are bipolar, BiCMOS or what. The biggest downsides will be: cost, knock-on changes (because the GBW, etc. are different), and approval.Tim

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2020, 01:39:53 pm
content: Quote from: T3sl4co1l on September 28, 2020, 01:26:07 pmMaking them forever is exactly the problem. Ancient analogue fabs are shutting down because they are so old people can't get spares for them any more. It looks like the remaining ones are only being kept alive through the reuse of parts taken from the ones closing down. Nobody is going to invest in new plant for tiny wafers, so a redesign for a process that exists for large wafers is usually needed. The original designers have probably retired, and the original design data has rarely been kept intact, so it will be a redesign from scratch.Quote from: T3sl4co1l on September 28, 2020, 01:26:07 pmNobody wants to tell customers about the processes used to make their devices, unless it has marketing value, like "uses TSMC's latest super duper 10pm process, with less than one atom per transistor". It can affect their flexibility in re-engineering parts for lower cost.

author: exe
author_rank: Unknown
timestamp: September 28, 2020, 01:58:09 pm
content: Quote from: coppice on September 28, 2020, 01:39:53 pmI recall reading that TI shrank their opamps two or four times, but I can't find any die shots to confirm this.

author: coppice
author_rank: Super Contributor
timestamp: September 28, 2020, 02:58:14 pm
content: Quote from: exe on September 28, 2020, 01:58:09 pmIn the early days the geometries were enormous. Devices could be shrunk quite a long way before people had to worry about how to maintain a high voltage tolerance. And they were shrunk. Quite often. While trying to avoid letting customers know how much things had changed, as it might worry them. Until characteristics changed, designs in production broke, and they had to quietly admit to specific customers what was going on. I went through this a couple of times in the 1970s.

author: magic
author_rank: Super Contributor
timestamp: September 28, 2020, 03:04:18 pm
content: They also do apparently migrate them to new processes on larger wafers from time to time. They discontinued a big chunk of National's audio line a few years ago quoting this very reason. Several TI dice on zeptobars show timestamps from the '90s or 2000s, no idea what was that which they replaced.As for opamps, I kinda assume it's bipolar unless stated otherwise. I have been hearing that bipolar tends to give more practical gain in analog applications. Also remember reading propaganda from National which claimed that complementary bipolar is advantageous over CMOS at high speeds because base width is controlled by diffusion depth rather than lithography resolution, which is cheaper to produce. That was a paper from the 2000s, though.OTOH, low power, low input bias, outputs reaching within a few mV of the rails - that smells CMOS.

author: David Hess
author_rank: Super Contributor
timestamp: September 28, 2020, 11:13:00 pm
content: Quote from: coppice on September 27, 2020, 11:57:57 pmThere will be industry consolidation until all analog ICs are made by Texas Instruments.Quote from: Zero999 on September 28, 2020, 07:53:43 amNothing stops you from testing and grading your own LM741Cs for a 40 or 44 volt operation. Tektronix used to do exactly this for some reason.Quote from: coppice on September 28, 2020, 01:39:53 pmGetting supplies like wafers for old processes is a problem also. You may have to buy the manufacturer of your wafers if you want to keep them available, and then what if they were also supplying your competitor?

author: exe
author_rank: Unknown
timestamp: September 29, 2020, 11:17:55 am
content: Quote from: David Hess on September 28, 2020, 11:13:00 pmDoesn't this compromise reliability? How to know if they can sustain this for prolonged period?

author: coppice
author_rank: Super Contributor
timestamp: September 29, 2020, 12:09:01 pm
content: Quote from: David Hess on September 28, 2020, 11:13:00 pmI suspect that sourcing small wafers for old fabs only becomes a problem when the last small wafer fab closes. The problem is the cost per square mm will be higher, as it becomes more of a specialist product.

author: David Hess
author_rank: Super Contributor
timestamp: September 29, 2020, 09:04:26 pm
content: Quote from: exe on September 29, 2020, 11:17:55 amNo, why would it compromise reliability? That is how the parts are tested in the first place.For a 44 volt 741, I would test the voltage follower configuration over the common mode input range while measuring the supply and input bias current at low and high temperature, for hours to days.Quote from: coppice on September 29, 2020, 12:09:01 pmNo, what I described has already happened even decades ago; old but popular parts may be redesigned for manufacturing on a new process simply because wafers for the old process are no longer available.

author: floobydust
author_rank: Super Contributor
timestamp: September 29, 2020, 10:44:51 pm
content: Are we saying there's been no improvements in analog IC technology? We should settle for 5V parts or just eat the 10x price hit to beat the 741's "features"?I saw National Semiconductor's standardized processes, high voltage (even to 170V) bipolar with better feature size, speed.I think you can do more with less silicon when you take these old parts and move them to modern, standard processes. We could compare 741 die shots to see how much it has shrunk.National Semiconductor Develops New Complementary Bipolar ProcessA Complementary Bipolar Technology Family With a Vertically Integrated PNP for High-Frequency Analog Applications

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 30, 2020, 12:43:16 am
content: What do you mean no improvements? We can do a heck of a lot more in 3.3V and less, than was ever possible in +/-15V or more, back in the day. Mainly because we aren't limited in complexity by keeping everything analog. The only place the voltage and current matter are where it touches the outside world; inputs can be divided down with precision resistors, leaving power output the last remaining at-scale, fully-analog challenge. The higher cost of which is easily justified by the much greater overall functionality, no?Tim

author: rstofer
author_rank: Super Contributor
timestamp: September 30, 2020, 12:07:23 pm
content: My Comdyna GP-6 analog computers are full of 741s, The model in the metal can which costs about $13 at DigiKey.https://www.oldcomputermuseum.com/comdyna_gp6.htmlhttps://www.digikey.com/product-detail/en/texas-instruments/LM741H-NOPB/LM741H-NOPB-ND/148206I suppose I could substitute more modern op amps but I won't. I have two of the GP-6s to maintain.

author: exe
author_rank: Unknown
timestamp: September 30, 2020, 12:30:11 pm
content: Quote from: David Hess on September 29, 2020, 09:04:26 pmShouldn't parts be designed to withstand a certain voltage? I can try, say, supply a 5V opamp with 10V and it might even work for a while, but I bet it won't last long due to overstress (of course, 100% increase in voltage is on the extreme side.).

author: floobydust
author_rank: Super Contributor
timestamp: September 30, 2020, 06:16:18 pm
content: I can't see how we're getting more - rail voltages are lower, costs are much higher even with the cheaper packages.Semi manufacturers could easily modernize the IC (i.e. 741) as a new part - but it makes sense to not upset the op-amp portfolio by offering a medium performance part that is low cost, and scuttle profits.I noticedTI addednewLM358Bwith 36V rail, 3mV VOS, up from 0.7 to 1.2MHz bandwidth. 44 years of progress as the near cheapest op-amp they offer at $0.05/1ku.Wow still the same 1971 Ford Pinto 0.5V/usec slew rate, can you feel the speed.

author: james_s
author_rank: Super Contributor
timestamp: September 30, 2020, 06:45:11 pm
content: There are lots of cases where more speed is not needed, or could even be a detriment. Faster parts are more likely to oscillate or pick up and amplify noise. If you're doing something where a slow part is fast enough and the cost is lower, there's nothing wrong with using the slow part.

author: tszaboo
author_rank: Super Contributor
timestamp: October 01, 2020, 07:46:54 am
content: Quote from: floobydust on September 29, 2020, 10:44:51 pmYes, or almost yes. Look at all the improvements that were made in the realm of reference voltages.The LTZ1000, 30 years ago could do sub ppm tempco. The LM399 ditto. In the meantime, there was the REF102 with 2.5ppm, released in 2000.Meanwhile in the last 20 years, the biggest improvement is probably the LTC6655. 2ppm. But whoopty do, they placed it in a hermetically sealed package, and charged 8 dollars for it. You know, the same package, that every 10 cent crystal oscillator comes in.You want to measure something accurately? Use the 30 year old part, because nobody managed to make any new parts that come close to it. And all these things are a handful of PN junctions and precision resistors.So yes, we have 24 bit ADCs in 2020, and nothing to drive them properly.

author: rsjsouza
author_rank: Super Contributor
timestamp: October 01, 2020, 05:19:25 pm
content: Don't forget that evolution usually is also tied to potential revenue. The fact nobody ever refined a process to reach LTZ or LM levels may be due simply to a lack of interest or too narrow of a market to be tapped into. The number of different voltage references available when compared to 30 years ago is impressive, but they are all competing in a segment with more relaxed demands.

author: coppice
author_rank: Super Contributor
timestamp: October 01, 2020, 05:42:35 pm
content: Quote from: rsjsouza on October 01, 2020, 05:19:25 pmI've been in new product discussions a few times where someone proposes something, people look at the numbers, and conclude that any more players in such a small market will mean everyone ends up making a loss. These projects do NOT move forwards. People are concerned about tit for tat move - we screw up their nice little niche, and they'll screw up one of ours. While you don't see new very high stability references appearing, you see plenty of improvement in the medium (5PPM to 20PPM) integrated references reaching into ever cheaper complex ICs. That's where the volume is.

author: David Hess
author_rank: Super Contributor
timestamp: October 01, 2020, 05:50:06 pm
content: Quote from: floobydust on September 29, 2020, 10:44:51 pmThe 741 and 324 style operational amplifiers rely on the very high base-emitter breakdown voltage of their PNP transistors to support a high differential input voltage range. New "optimized" processes do not allow that. I am not even sure how they make high differential input range parts on a modern high voltage process; I did a search a couple months ago and they were all limited to 7 volts at most. Low voltage parts of course have no issue with this because they should never see a high differential input voltage.JFET input parts could do it, and this is one of their advantages, but how many of those are made on a modern process? None?

author: David Hess
author_rank: Super Contributor
timestamp: October 01, 2020, 05:57:51 pm
content: Quote from: exe on September 30, 2020, 12:30:11 pmFor 741s and similar ICs which were originally built on the old NPN only process, it is more of a yield problem. The criteria for failure at a higher voltage was excessive leakage which depended on process variation. As far as I know, there was no separate process for 44 volt parts as this would have been completely uneconomical.The same is true of bipolar transistors; the maximum Vceo varies considerably from part to part and the same part will be graded into multiple part numbers reflecting its tested Vceo.A part designed for 5 volts maximum, like TTL, usually takes advantage of the maximum Vbe of roughly 5 volts which varies much less than the Vceo. 5 volt parts do not have to be designed to consider base-emitter breakdown. These same parts however can usually support much higher output voltages on their open collector outputs.

author: coppice
author_rank: Super Contributor
timestamp: October 01, 2020, 06:47:41 pm
content: Quote from: David Hess on October 01, 2020, 05:57:51 pmWhen the 741 was designed a 5% yield was considered a good day. Now its close to 100% for simple devices like that. Times have definitely changed.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 01, 2020, 06:59:09 pm
content: Quote from: David Hess on October 01, 2020, 05:57:51 pmI have a batch of transistors whose actual breakdown voltage is astronomical compared to the specification. Does/did it ever happen in production, that the process improved to the point where even the lowest specced parts easily achieved the performance of the (older) highest rated parts - so the lower rated parts effectively became price/performance "bargains" (but not advertised, so nobody would ever know)?

author: Kleinstein
author_rank: Super Contributor
timestamp: October 01, 2020, 08:50:25 pm
content: As far as I have heard most of today's TL082 OPs are also low enough in noise to meet the TL072 specs, which is the lower noise variant, otherwise identical. Similar it may happen with other parts - they may not get many of the lowest voltage class transistors. So chances are quite a few may have considerably higher than specified break down voltage. Similar I would not be surprised to get a bag of 1N4001 with all higher than 200 V break-down voltage.Chances are they decide to mark them also according to orders, not just measurements.The same may happen to LM358/LM2904 (lower voltage grade).The PNPs in the old NPN base process are lateral parts with the dimensions defined by lithography. There is no problem making larger structures with a high resolution process. So they should be OK to still build the old style transistors. A few days ago a found an article showing a lateral BJT in an standard 1.2 µm CMOS process and an OP with 2 such BJTs for the input and the rest MOSFETs. So kind of mixed MOS and BJT the other way around than in the early days. The lateral transistor were supposed to be even good quality (low noise, good gain, though slow) - not the marginal PNPs in the 741.

author: tszaboo
author_rank: Super Contributor
timestamp: October 01, 2020, 10:36:58 pm
content: Quote from: rsjsouza on October 01, 2020, 05:19:25 pmNot everything is about profit, or it shouldn't be. I have the feeling that humanity cannot get anything done anymore, because of the search of immediate profit. I've seen companies do nothing, and let engineers sit idle, rather than have them working on a project. They calculated, that the NRE cost of the project is to big, and that would eat up the profit. I guess these things only make sense if you have an MBA.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 02, 2020, 02:50:58 am
content: Quote from: NANDBlog on October 01, 2020, 10:36:58 pmI've noticed the same thing: People prefer doing "nothing" to doing "something"... as you say, probably because "something" is perceived to have a cost associated with it, whereas doing "nothing" has somehow escaped that analysis...

author: coppercone2
author_rank: Super Contributor
timestamp: October 02, 2020, 02:58:10 am
content: if it works why change it, its like asking why some things are still made of wooddoes a kitchen knife need a neotitaniumsteel handle? no

author: floobydust
author_rank: Super Contributor
timestamp: October 02, 2020, 04:02:04 am
content: Look at the other side - the op-amp portfolio manager needs new products, new profits so they constantly roll out new op-amps, per the MBA way.We think cost is driven by silicon area, but I think it's reverse - they have a pricing matrix using features such as offset voltage, speed, RR etc. to determine the pennies to charge and fill some niche left out by competitors.It's a problem now with the mergers and acquisitions where all of a sudden a corporation now owns previously competing portfolios. What a mess. They have to swing the axe and thin out the lineup. Consolidation (PMI, SSM, Burr Brown, NS, LT) will lead to less competition and poorer offerings because innovation is not really needed. It's ADI vs TI now.P.S.- on the speed issue, I foundLT14940.001V/usec slew rate on super low power 1.5uA, a neat part.

author: tszaboo
author_rank: Super Contributor
timestamp: October 02, 2020, 08:44:03 am
content: Quote from: floobydust on October 02, 2020, 04:02:04 amNo, for sure not cost driven. I mean, LT is charging the same amount for a single opamp, than chinese companies for a reel of MC34063 clone.About the mergers, it is absolutely a mess. They started obsoleting parts left and right. Now we have to look out for parts, like BJTs and zeners, because they might stop producing them. And for sure, you dont care about this in a washing machine. For me these are used in a certified product, and if I have to change it, it is several thousand EUR just to certify the product again.

author: coppice
author_rank: Super Contributor
timestamp: October 02, 2020, 09:41:04 am
content: Quote from: floobydust on October 02, 2020, 04:02:04 amNo sane portfolio manager wants new products. They want new sales of existing products, since that doesn't involve a lot of NRE and a long time to market. New products are a last resort when pushing the existing products fails. Most new semiconductor products come about from 2 driving forces. The sales team keep feeding back requirements they see from customers, that existing products can't fulfill. The technology side keeps showing some interesting results they can achieve, either today or in the near future. The portfolio manager's role is to find where those 2 inputs match, and an appealing new product can be defined. People rarely develop new semiconductor devices without an extensive survey of what customers are actually looking for, and when they need those parts. One of the key things most companies require for a development project kick-off is some key named customers, their expected volumes, and the market window for each customer.

author: coppice
author_rank: Super Contributor
timestamp: October 02, 2020, 09:47:27 am
content: Quote from: NANDBlog on October 02, 2020, 08:44:03 amMost of the obsoleting is not about mergers, although mergers are often the trigger point for action. Obsoleting is mostly about lack of demand or obsolete production equipment. While some ancient devices, and compatible derivatives, like the 555, still sell by the billion, many old devices still available sell just a few thousand parts per year. How low can you expect demand to go, and still have the part listed as available?

author: tszaboo
author_rank: Super Contributor
timestamp: October 02, 2020, 06:22:51 pm
content: Quote from: coppice on October 02, 2020, 09:47:27 amWell, kinda. Remember Fairchild? They had no obsolescence policy, until ON bought them. ON is obsoleting like half their portfolio as we speak.Microchip throw out entire product lines from Atmel.Littlefuse just throw out IXYS's solar panel portfolioIRF was decimated by Infineon. When they bought them, it was synergy (sound of angels in the background), after a year it was too much overlap.

author: coppice
author_rank: Super Contributor
timestamp: October 02, 2020, 08:19:46 pm
content: Quote from: NANDBlog on October 02, 2020, 06:22:51 pmA blanket no obsolescence policy is ridiculous, and obviously won't be kept to. When they sell just a few hundred a year, do you really think its viable to not obsolete the part? When the fab is unmaintainable, do you really think its viable to not obsolete the part?The first time I got to see from the inside the point at which old parts get dropped I was astonished how long that vendor had continued with supply. Many of the parts dropped on that occasion sold just a few thousand per annum, and hadn't sold in decent quantities for years. Vendors serving things like the consumer and computer markets tend to have fairly short windows of opportunity for their parts, and are dropping them all the time. Vendors serving industrial customers are at the opposite end of the scale. Large vendors, serving many markets, may have different practices in each division.Quote from: NANDBlog on October 02, 2020, 06:22:51 pmI wonder how many of those parts were sold per annum? I doubt too many high volume, decent margin parts were dumped at the drop of a hat. Political infighting obviously plays a part, but its mostly down to volumes, margins, and the technology still being available to make the parts.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 02, 2020, 08:55:45 pm
content: Quote from: coppice on October 02, 2020, 09:47:27 amAt some point, it must make sense to do a "final production run" and put a couple of crates into a warehouse, to sell out of over the next e.g. 5-10 years before finally selling the last remnants to stockists of esoteric components. That has to make a lot more sense than keeping an obsolete production line operating for a very small number of parts annually...

author: coppice
author_rank: Super Contributor
timestamp: October 02, 2020, 09:51:47 pm
content: Quote from: SilverSolder on October 02, 2020, 08:55:45 pmI bet you could start a business providing that end of life stuff as a service. Keep banks of dies in controlled conditions, and do packaging and test on demand. Maybe you could call it something like "Rochester Electronics".

author: rsjsouza
author_rank: Super Contributor
timestamp: October 02, 2020, 10:22:32 pm
content: Quote from: NANDBlog on October 01, 2020, 10:36:58 pmIt depends on how you define profit. In the cold war era, profit was the gain over the ever present danger of the other side and money was not really a problem for these state of the art projects. Fast forward to today and the scenario changed a lot.My own example is a cold war era Power Designs 5015A power supply that once belonged to General Dynamics. You would be very hard pressed to find a modern analog linear power supply with that level of build quality and finesse. Oh well... Modern times.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 03, 2020, 03:18:54 am
content: Coppice;Today I was wondering precisely about Rochester Electronics.Wondering from where do the wafers come from.I wondered if they had purchased obsolete fabs, shipped them to the Far East, and continued production of old parts.But your assessment of Rochester packaging and testing NOS wafers makes much more sense.Do you know this as a fact?EDIT: searching the web, apparently Rochester is doing it both ways.

author: coppice
author_rank: Super Contributor
timestamp: October 03, 2020, 11:23:30 am
content: Quote from: schmitt trigger on October 03, 2020, 03:18:54 amRochester's web site tells you the things they do. They work with the original vendors of a part in most cases. They take either wafers or completed parts from them, plus all the packaging and test documentation needed to complete the parts to their original spec. Assembly and test is a commercial enterprise these days. Even the biggest silicon vendors outsource much of their assembly and test to specialist A&T houses in Asia. Packages don't go obsolete very often, and testers don't change very fast. So, as long as the wafers area stored in optimal conditions, Rochester can get them assembled and tested as the would have been originally.I am not aware of Rochester operating any fabs. I can't imagine how that would work. If you have a hit product and need more capacity there are usually only one or two other fabs that can run the same process, which you might be able to expand into. The older things get the less compatibility you see between fabs. You probably can't even put the masks into the lithography machine, unless you have just the right machine to match your masks. There is very little compatibility in the fab business.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 03, 2020, 01:26:01 pm
content: Wondering why it is cheaper to store them as wafers and build the ICs later, rather than just asking the original supplier to make a batch of product on the lines that have already been set up for it, before powering down for the last time... and storing the output of that run? Is it because you then have flexibility to put that chip into different packages etc.?

author: David Hess
author_rank: Super Contributor
timestamp: October 03, 2020, 02:20:28 pm
content: Quote from: SilverSolder on October 01, 2020, 06:59:09 pmI have seen that happen with some transistors where the lowest specified parts became unavailable, and were eventually discontinued in favor of the higher voltage parts.Quote from: Kleinstein on October 01, 2020, 08:50:25 pmNoise tests tend to be time consuming which adds cost to production, so it is not surprising that TL072s often meet the noise specification for the TL082. On the other hand, I have hardly ever seen any price difference when buying these parts so I buy the presumably noise tested TL082 series in favor of the TL072.QuoteA couple weeks ago I searched for examples of operational amplifiers which support a high differential input voltage range that are built on a modern process and found nothing. I was specifically looking for modern replacements for the 741 and 301A types of operational amplifiers. The closest ones I found are single supply 324/358 type improved parts like the LT1006/LT1013/LT1014 which obviously make use of high voltage PNPs but are hardly modern despite their high performance.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 03, 2020, 03:05:42 pm
content: For OPs with a larger input differential the main option to look at are FET input types (e.g. OPA196/7). Even there some JFET types (e.g. OPA170-172) have a limited input differential. A moderate cost (can be comparable to 741), slightly improved lm358 is the MC33172.The TL072 is the version with lower noise specs, the TL082 was the low cost version that allowed more noise. Chances are these are not individually tested - probably just a few per batch. I also noted essentially no price difference.The lower grade transistors (lower gain bins or lower voltage bins) can become rarer though still in the program but less likely at the distributors. There however one exception: the higher supply variants for some OPs are not taking over. For some reasons there are still LM2904 ( = lower voltage grade of LM358) available - could be just LM358 with less testing for the penny pitchers.

author: tszaboo
author_rank: Super Contributor
timestamp: October 03, 2020, 03:18:50 pm
content: Quote from: coppice on October 02, 2020, 08:19:46 pmThe no obsolescence policy was rolled out in 2013, and ON bought them in 2016, so we will never know if this would've worked. In all fairness, Fairchild had a fairly "established" portfolio, they weren't chasing trends, just making parts for industrial applications. Only a few new IC was for new applications, like SIM card switch and other low-tech parts.IDK, how many parts Atmel or IRF was selling. I think the part which got canned was Atmels FPGA portfolio, that was very old designs. So you can imagine, anyone using those had a very good reason to use them.Like that company, open sourcing their respirator. They used some 20 year old ST microcontoller.The reason to keep these going is simple. They are used in the train your are taking to work. In the hospital equipment. In the nuclear powerplant controller board. Even if you only sell 100 of these parts, we need these parts.