General > General Technical Chat
Do semiconductor datasheets suck?
ataradov:
--- Quote from: Smokey on November 28, 2023, 07:20:40 am ---Then release for public.
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By the time things are released to the public, there are typically multiple real designs by early access / lead customers. They find far more issues than an in-house engineer ever would. This is still a very small number of issues compared to what happens during mass availability.
--- Quote from: Smokey on November 28, 2023, 07:20:40 am ---It would be amazing to have a direct link to give datasheet feedback for that specific document.
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It would be very hard to do, especially as products mature. A lot of TI documents for old parts are poor quality scans of paper data books. Those things are not going to change no matter how much feedback you give.
I still receive requests to make changed to the documents that were last updated in 2011. This is simply not happening. I don't know if anyone even have source for those documents.
--- Quote from: Smokey on November 28, 2023, 07:20:40 am ---See what is giving people a hard time or is confusing and figure out how to add that information into the datasheet.
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There are common and real issues,. which could be addressed. But in practice for established documents, majority of requests are something that is in the datasheet already. People just don't read or can't use search. And then everyone thinks that the issue they faced is the most obscure one (they can't be at fault., of course) and demand that their specific use case is addressed as soon as possible in the chapter.
It is impossible to make everything be the first thing in the chapter. If it is 1000 page document, some things will be deep.
And as far as fast iteration goes, it is also not easy. You are looking at one document, the company looks at 100s. And the number of technical writes is limited.
Smokey:
The scans of old datasheets are the worst. That has to hurt sales at some point. I'll try to skip using a part with a scanned datasheet if there is a viable alternative.
There are always going to be the users that put in zero effort to read the datasheet. But from my experience there are still a significant number of people who put in the effort but the datasheet just wasn't clear on some point or another so they have to ask for clarification. Go check out the TI E2E forum. It's a lot of the same questions. This is the stuff that needs to be revised, or rewritten, or put in big bold text or something.
T3sl4co1l:
Jesus. Well, that explains why -- well, fortunately no one has to design systems with it anymore, but logic gates for example show an impossibly wide margin. The best 74HC might supposedly outperform the worst 74LVC. Which just doesn't make any fuckin' sense. Add up say three max gate delays, and you're already over the timing constraint at 10, 20, 30MHz? And practical logic circuits (say you were building an ALU) need way more than three delays. Real 74HC builds (there are a few out there these days, though I don't have any links handy) achieve over 10MHz clock rate I think, flagrantly violating datasheet constraints. But the datasheet is a lie. But does that make it "ok"?... ::)
--- Quote from: 16bitanalogue on November 27, 2023, 07:22:02 pm ---Depends on what you mean by sucking so bad. The reality is app notes (many, not all) are conceptual and tied to a release of a product to help promote it. The other reality is the authors will have varying levels of education, experience, and practical knowledge. This is all very generic, but if someone expects an appnote to be some 6-sigma design over PVT (process, voltage, temperature) for the device and passives, you are looking in the wrong place. They are not meant to be "copy this and you will have no problems". This is a long winded way of saying, app notes (modern app notes) are MARKETING material.
At least the designs are simulated to help bolster the concept, then some may actually be built in the lab and tested. TI and ADI have circuit designs to this affect.
--- End quote ---
In this case I mean regards to factual accuracy, or theoretical understanding; indeed, I wouldn't expect them to do much if any statistics, appnotes should be more about practical embodiments than ongoing process variables.
The average appnote looks written by interns. Maybe reviewed by engineering staff, maybe not. My favorite one to rag on is probably this,
https://www.ti.com/lit/an/slpa010/slpa010.pdf
the author(s) clearly lack fundamental understanding of the dynamics they're attempting to control. No equivalent diagram is given; Fig.20 finally adds an inductor to the loop, but only to illustrate gate-loop coupling; Fig.18 is basically their smoking gun, and they've failed to eliminate the symptom, only reduce it -- at expense of efficiency; no units are ever given (they've essentially measured Ls but stop short of actually writing it down); the test case isn't described (it's a sync buck, but what V, I, Fsw? -- they eventually say 12V in, 1.3V 40A out, 1MHz); component selection isn't discussed; only two layouts are tested, leaving still-better ones on the table; the PCB stackup isn't even mentioned (it's probably 4+ layer); there's even a dimensional error in an equation (page 12, \$L_p\$), though surprisingly the subsequent equations are correct, so this seems a typo.
I suppose it's interesting that this article was produced in regards to their NexFET technology; they do have remarkably low Crss, and perhaps one should read into this that the most effective reduction strategy would be to put some back? :-DD (An R+C from D-G is something I should try more often, honestly.)
But that's just one very particular example. The most galling of all, to me, is probably the absolute unbridled confidence with which appnotes present their ideas. I would dare say you could train a GPT on technical documents, and end up with merely sub-par copy (which I'm sure would impress the corpos..). There is never any presence of mind, any checking of confidence, nor review of resources or references (they do occasionally give references, indeed this one gives two, though I haven't noticed where if at all they're referenced in the text). The biggest sin therefore is that readers assume they are authoritative.
Like 60% of relevant questions on the internet are "I did it following the appnote so it must not be that" (with the correct answer: "appnote is wrong do it this way"), compounded by 60% of other answers being "do it according to the appnote". :palm:
Thanks by the way for hanging out!
Tim
magic:
--- Quote from: ataradov on November 28, 2023, 07:36:04 am ---It would be very hard to do, especially as products mature. A lot of TI documents for old parts are poor quality scans of paper data books. Those things are not going to change no matter how much feedback you give.
--- End quote ---
Ehm, any example currently on ti.com?
Say what you want about TI, but they are nuts about reformatting datasheets to their latest internal standards. Sure, some old and almost forgotten parts haven't received an update in over 20 years if there is nothing interesting happening to them, but even if they look like vintage databooks they are cleanly rendered PDFs with real text and vector graphics. High profile parts receive regular updates and look like any new part's datasheet. See LM317 for example, the current version has colorized typical characteristics plots and all the typical TI stuff: recommended operating conditions, "device functional modes", typical applications, board layout example, and so on. Some of it came from vintage LM317 datasheet, some of it had to be added.
Datasheets of products acquired from BB and NS haven't looked like the originals for years.
T3sl4co1l:
Not hard to find examples; https://www.ti.com/lit/ds/symlink/cd4011b.pdf perhaps surprising that it's not been updated for such a basic datasheet, when others have (4013 for example).
Oh heh, another gripe, but this is more of a historical baggage and appnotes thing -- parts like TL494 always, only and ever show voltage-mode configurations. Even though objectively better current-mode operation is possible, and hardly any added complexity. I expect this comes down to, it's easier to repeat old material, even if it's bad (read: performs worse, or rarely actually is actively harmful). Also a bit less topical, as it's a phenomenon which affects everyone everywhere, from oft-archived and repeated schematics floating around communities since the printed era, to original authors repeating material at least as a baseline (if you're repeating what was previously accepted as valid, surely you're not doing any worse than previous work did), but also perhaps limited for other reasons, like not being aware of alternatives, or not being able to demonstrate them given constraints (show value proposition + work to design and build it + document it, etc.).
Tim
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