Datasheets becoming more useless and restricted over time - Page 1
Forum section: electronics / general

author: Lance
author_rank: Frequent Contributor
timestamp: April 14, 2022, 08:38:06 am
content: Hi all, I'm not sure if this is an actual trend or not. It's just something I've noticed and wanted to get some more thoughts on. I haven't seen it being discussed elsewhere unless I just used the wrong search terms. I've been working professionally as an EE for about 7 years now, but I've been doing this type of stuff for basically my entire life.I've noticed a trend where information on parts and datasheets are gradually becoming locked down. I'm not talking about specialty aerospace or other restricted parts, I mean parts that you can pick up on digikey or any other public market. 10+ years ago this was generally only true for more specialty chips. Fancy SOCs with 1000+ page datasheets, ASICs for encrypted keyfobs, etc. You had to sign an NDA and be an actual company to get them.I'm seeing this move into less esoteric devices, and I've got a specific example. Toward the end of university I managed to gather enough parts and cobble together an ebike using some LiFePO4 cells. I was really looking forward to building a BMS and learning all about the details. I planned to base it around one of the earlier versions of the LTC6812. Life happened and the project sat for a bit. I maintained the pack with a DMM and a simple charger. Many years down the road I have much more experience under my belt, more than two pennies to rub together, and those cells are totally dead. I decided to pick the project up again, so I designed a new pack using 18650's and went shopping for a BMS IC.The LTC6812 is a good option. This datasheet is excellent, it has everything you need to know to run the devicehttps://www.analog.com/media/en/technical-documentation/data-sheets/ltc6812-1.pdf.Too bad the part is out of stock everywhere, so I went looking for alternatives. I noticed the newer TI and the rebranded Analog Devices parts have datasheets which are effectively just ad flyers. Nothing about how to actually use the parts.https://www.ti.com/lit/ds/symlink/bq79656-q1.pdfhttps://www.analog.com/media/en/technical-documentation/data-sheets/adbms6830.pdfThe sorts of projects these get used for aren't on the level of a beginner engineer or casual hobbyist. However these devices aren't performing any exotic functions, older versions in the product lineups have the usual fully complete datasheets. So what gives? The companies seem to want everybody to sign an NDA to use these parts. Or are they just so new they haven't gotten around to publishing the full documents yet? If this trend is real and spreads I think it will have a negative impact on the profession. As a student details in the old LT datasheet made me realize I had some significant gaps in my knowledge I needed to fill before tackling that project. I didn't have the money or skills to tackle the project at the time, but the datasheets alone were a useful learning tool.I haven't seen this spread to more common generic parts like opamps, or other less specialized ICs like matrix drivers yet. However in my dayjob I've seen this creeping into what I'll call semi-specialized parts like these BMS chips.I wonder what the long term trend looks like. Are we heading for a future where using anything other than the most generic parts requires the backing of a company and being signed to secrecy? I'm curious if anyone else has noticed this. Am I just imagining this or is this trend real?EDIT: I retract that statement about matrix drivers:https://www.ti.com/lit/ds/symlink/tlc6983.pdfA whole 15 pages long.

author: DC1MC
author_rank: Super Contributor
timestamp: April 14, 2022, 09:42:35 am
content: You took some very "fresh" parts in the absolute hottest and the most critical part of the industry and you wonder were are the detailed datasheets and nice application notes from which you can design your projects ?Well I have some bad news, soon there will be no more whining about ginormous amount of documentation that one need to read and understand to be fully capable of use a specific chip/MCU/whatever, because there will be no more of this stuff, once gone will stay gone for ever. And no, you will not be able to vote with your wallet, maybe for a short time until everybody synchronizes and the "obsolete" parts with their abundant docs will become EOL.A ultra-simplified data-sheet, a demo board with some software for evaluation, a super patched Yocto for Linux running MCU and that's it ("...we comply with Open Source licenses as little as legally possible, please use our supported binary firmware image...". And hey, if someone still use those Borscht sensors, a fully opaque "AI" to calibrate them will be available, an that's it, basta.So what about designing my own products, you may ask ?!?Well, enters the "XXX Company Engineering Services", you give them the specifications, pay and get a nice Chinese design, also for the continued revenue stream you'll also get support contract. No, access protocols are proprietary and only available via our "IoT Cloud Services", for a moderate monthly fee/device, you get the latest software updates and bug-fixes. You'll only have a say in the branding of the unit and the shape of the PCB, maybe.It may sound, bleak, paranoid or far fetched, but this is the global trend, the time of small/medium design houses with their little niches, JIT supply and "I design it here, produce it in China and slap 10000% price on it" are all gone and the consolidation will happen fast. Now you can see them (including here) twerking like the suffocating fish out of water, desperately scrambling for the bottom of the barrel parts and waiting for good old times of unlimited availability, easy full BOM ordering and fast delivery to come back, any time soon, the "hoarders will be punished and sell their stock for pennies on dollars...".Is really sad and pathetic what is happening, this the world now and we're joining the watch makers and other dinosaurian jobs, some extra/ultra specialized design houses may survive, but most will be just gone or be assimilated.Cheers and have a nice Easter celebration for those who does it,DC1MC

author: Whales
author_rank: Super Contributor
timestamp: April 14, 2022, 11:05:14 am
content: Quote from: Lance on April 14, 2022, 08:38:06 amPerhaps this is revealing. Just as 2nd hand bookstores end up only stocking bad books (because they are the ones that survive on the shelf).Good, easy to use and documented parts: out of stock due to demandCrappily documented parts: available, no one wants to buy them.

author: JPortici
author_rank: Super Contributor
timestamp: April 14, 2022, 11:45:04 am
content: Quote from: DC1MC on April 14, 2022, 09:42:35 amor... one needs to look at the product page more carefully, because in thedocuments sectioni can see thishttps://www.ti.com/lit/ug/sluuc37b/sluuc37b.pdfI would say it's not the norm for TI but i say it's not unexpected for this kind of part

author: Lance
author_rank: Frequent Contributor
timestamp: April 14, 2022, 04:38:36 pm
content: Quote from: JPortici on April 14, 2022, 11:45:04 amThat's just a guide for the devkit, doesn't have any details on the actual part in question.Quote from: Whales on April 14, 2022, 11:05:14 amI was surprised to see those in stock given the general shortage of chips we're in right now. I've seen lead times 1-2 years long for things as simple as opamps.

author: Siwastaja
author_rank: Super Contributor
timestamp: April 14, 2022, 04:51:05 pm
content: It's only because all the normal parts are out of stock now. So whenever you click "in stock" checkbox, you will get a selection of very weird parts, something you would have not bumped into during normal times pre-COVID.Those parts scream complexity. My take on BMS:1) make it as simple as possible,2) try to have full control over everything, especially algorithms.Both of these points prevent using the kind of parts you linked to, anyway. In reality, all you need is the voltage shifting magic to be able to measure the cell voltages. Rest is code, and it's better if it's in your own hands, unless you are totally clueless which you probably aren't.

author: Lance
author_rank: Frequent Contributor
timestamp: April 14, 2022, 05:46:20 pm
content: Quote from: Siwastaja on April 14, 2022, 04:51:05 pmThe initial appeal of the LT part was that it just acted as a measurement frontend and left the control logic to me. Not that I couldn't build it out of discrete parts, it's just a hassle I'd like to avoid if possible. These alternates can function in that manner, the extra features are neat but not what I was really looking for. In any case the ADBMS part is looks like a newer analog branded version of previous LT stuff.

author: tom66
author_rank: Super Contributor
timestamp: April 14, 2022, 10:13:00 pm
content: I believe Tesla use LTC6812 or a variant in their battery packs to measure cell voltages. They probably have all the supply right now!

author: Lance
author_rank: Frequent Contributor
timestamp: April 15, 2022, 12:31:00 am
content: Quote from: tom66 on April 14, 2022, 10:13:00 pmYeah, I was disappointed but not surprised at all to see they were out of stock everywhere. They're quite popular. My disappointment was more around seeing how all the newer iterations of these parts have locked down information.

author: rsjsouza
author_rank: Super Contributor
timestamp: April 15, 2022, 09:18:04 am
content: Quote from: Lance on April 14, 2022, 08:38:06 amLance, the product page has a note to request more information, including a complete datasheet.This is very unusual for TI parts but, since this is an automotivw qualified part (suffix Q1) that is probably in very high demand right now, there may be a chance they are actively trying to screen customers interested in it.

author: coppercone2
author_rank: Super Contributor
timestamp: April 15, 2022, 06:24:03 pm
content: Well keep in mind its not always that the information is being hidden, its that its not gathered in the first place, in order to reduce development cost. Fly by night engineering.Since the best option the design engineer has is to leave the company after a few years to get better pay elsewhere, and no one knows how to test that stuff and assure test quality, its better not to write the document in the first place so the new guy does not get overwhelmed.I bet every one of the upper management types in your company will say that he does not plan on staying for more then a 'little while longer' because of raises (they have to remain threatening for people in accounting).

author: Lance
author_rank: Frequent Contributor
timestamp: April 20, 2022, 02:16:16 am
content: Quote from: rsjsouza on April 15, 2022, 09:18:04 amFor work stuff TI has generally been prompt, but I recall past experiences as a student where I just never got a reply. You do make a good point with the current unusual circumstances. Maybe this is just a temporary thing.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: April 20, 2022, 03:29:12 am
content: Linear Technology has been guilty of this even before the analog devices takeover. The LTZ1000 datasheet much beloved by volt-nuts has shrunk and simplified over time.Another minor thing I found irritating, they called a whole passle of new vregs the LT308x series LDO's and sneakily hid the actual drop-out voltage. By not including the actual drop-out in the first page spec list. Eventually they introduced a selector tablehttps://www.analog.com/media/en/technical-documentation/product-selector-card/ldo.pdfBut back then they made you dig for it. LT3085 = 275mv a true LDO versus LT3082 at 1.3V quite a range!

author: tooki
author_rank: Super Contributor
timestamp: April 21, 2022, 06:31:16 pm
content: Quote from: coppercone2 on April 15, 2022, 06:24:03 pmThat is an extraordinary claim which, absent extraordinary evidence, should be paid no heed.Quote from: coppercone2 on April 15, 2022, 06:24:03 pmI’m sorry, but if you think the companies don’t create and thoroughly document exhaustive test procedures for a chip, then you are either insanely naive or willfully ignorant. The cost to bring an IC to market is significant, and the damage to the company reputation enormous if quality is not consistent.Those internal specs, of course, have little bearing on what information is made public.If a data sheet actually removes binding specs over time, a less-conspiratorially-minded explanation is that process changes have made it impossible to consistently meet that spec. Process changes aren’t done because of malice or stupidity, but because it isn’t economical to run that process any more (e.g. sales of products made with that process have fallen enough that it isn’t economical to keep a fab open for that process, so they close or sell the fab), or because some process input (raw material, parts, equipment) is no longer available. So you switch to a different process, and that process produces different characteristics.

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 21, 2022, 06:46:38 pm
content: Mostly agree with tooki here.One of the main reasons for "poor" documentation is just that technical documentation is very hard to write. One thing that is often true though, is that companies tend to cut on those dedicated positions - specialized technical writers - and use random engineers to do that. Your basic engineer is known to be relatively poor at writing tech docs. The reason is not necessarily just cost reduction, it's also the way management is supposed to be done these days: flexibility. Avoid too specialized positions. Make employees replaceable.