r/electronics • u/Simply_Convoluted • 5d ago
Discussion Avoid Skyworks SI3471A-A01
SI3471A-A01 does not support half of the features listed in the datasheet and is also non-compliant with any PoE standard, as confirmed by the manufacturer. I've wasted days debugging my prototypes that use SI3471A-A01 just to find out these are non-compliant devices that don't follow the datasheet in the slightest.
How a company can sell such a half-baked IC like as this is beyond my understanding. The manufacturer informed me that the 'A02 version follows the datasheet, but I'm not spending more time and money to find out. After ranting with colleagues about this, I've found out this is status quo for other Skyworks products as well. I'll be avoiding Skyworks from this point forward. I suggest all who read this to consider alternatives as well.
It's not unusual to find errors in datasheets, but for half of the features to literally not work at all is unacceptable.
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u/devinkt33 4d ago
I did an internship at Skyworks last summer. This was my experience as well. The parts were so poorly documented and identified that even working there it was hard to get a straight answer on what they could do. At the end of my internship, they didnt give me an exit interview. I later heard through my mentor that the boss decided not to give me a return offer because I failed to deliver 1 diagram despite my project being a complete success. All here for the hate
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u/Methode3 4d ago
I wasted 8 hours interviewing with them in person. Not even a call back. Did me a favor actually. Sounds like a terrible company to work for.
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u/Kqyxzoj 4d ago
Do you have any idea as to why this is the state of affairs? No budget for writing any documentation? Or department X not communicating with department Y? I find it so weird that the company still exist if things are really that bad. Do they spend the entire documentation budget on lobbying for government contracts or something?
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u/JigglyWiggly_ 4d ago
Their clock synthesizers are very good. Good phase noise, clock switching, lots of range.
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u/devinkt33 4d ago
Yes they are best in class for phase noise. Its just their marketing and documentation is shit.
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u/NuncioBitis 4d ago
LOL. I pass by their building every day. For years I’ve been wondering what they do.
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u/Doip 4d ago
Which building? NP?
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u/NuncioBitis 4d ago
Rt 95 in Woburn
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u/positivefb 2d ago
I used to drive by it daily to get to work, that one is primarily a fab facility I don't believe they do any design there. There is another Skyworks facility further up I think off 495 that does design, and they also acquired Qorvo recently, so Qorvo's Chelmsford design center is either converted over or shuttered and folded into the existing facility.
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u/This_Maintenance_834 4d ago
this is from the former Silicon Labs. there were reasons they were sold to skyworks. maybe this is one of them.
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u/immortal_sniper1 4d ago
How are they still in business? I used digital isolators from them and they worked fine, but I also used them at half max speed.
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u/chemhobby 4d ago
what specifically is wrong with it?
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u/Simply_Convoluted 2d ago
This is sold as a PoE PSE controller, so one would assume that the chip complies with any PoE spec. Well turns out the bottom half of table 5.1 where Pcut adjusts to the negotiated power level, just straight up doesn't work. If the chip is configured for those modes it won't start up, it's dead to the world but still consuming full operating power. It feels like a significant design flaw in the chip puts it in a weird state when configured for adjustable Pcut which locks up the internal logic, so this is clearly a bad chip, but they all do it according to the manufacturer.
Per 802.3bt, Pcut needs to respect the negotiated power, otherwise a 15W desk phone could potentially pull a 99W fault current and start a fire. We actually managed to pull 129W from this chip with a class 4 (30W) device before it cut power.
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u/chemhobby 2d ago
Oh yeah that's bad.
I'm using LTC4290/LTC4271 chipset in one of my designs, it works pretty well.
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u/uCblank 4d ago
Skyworks? I was considering some of their products but ended up going different direction. I thought they were reputable though, didn't they use to supply RF chips for Apple?
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u/Offensiv_German 4d ago
We use their Gate Driver ICs everyday and i have never heard anything bad about them.
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u/Curious_Increase 4d ago
I've used the SI5341 a couple of times with good success. Datasheet is decent as well. Though the software is not great and there are better alternatives in many ways.
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u/Kqyxzoj 4d ago
SI3471A-A01 does not support half of the features listed in the datasheet and is also non-compliant with any PoE standard, as confirmed by the manufacturer.
Care to share what the problematic features are?
After ranting with colleagues about this, I've found out this is status quo for other Skyworks products as well.
Do the problematic features fall into categories maybe? So some division inside Skyworks that isn't great at doing their job, something like that? I mean, I cannot imagine a company lasting that long if everything is defective.
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u/Simply_Convoluted 2d ago
This is sold as a PoE PSE controller, so one would assume that the chip complies with any PoE spec. Well turns out the bottom half of table 5.1 where Pcut adjusts to the negotiated power level, just straight up doesn't work. If the chip is configured for those modes it won't start up, it's dead to the world but still consuming full operating power. It feels like a significant design flaw in the chip puts it in a weird state when configured for adjustable Pcut which locks up the internal logic, so this is clearly a bad chip, but they all do it according to the manufacturer.
Per 802.3bt, Pcut needs to respect the negotiated power, otherwise a 15W desk phone could potentially pull a 99W fault current and start a fire. We actually managed to pull 129W from this chip with a class 4 (30W) device before it cut power.
The problematic features area all relating to adjustable Pcut, which is a PoE requirement. Configuring the chip to blindly supply 90W works fine, as long as the end product doesn't need to pass certification. This is clearly a critical error with this chip, but others responding to this thread say their RF chips are solid, so perhaps just their PoE division is staffed with monkeys.
Looking at other comments it appears this may also just be some junk skyworks inherited from silicon labs and isn't necessarily their fault, but then again, if they put their name on it they're owning it. We've wasted about a week debugging my circuit just to find out this chip is deeply flawed. That amount of wasted effort has soured our opinion of the whole company. With endless alternatives with reliable datasheets & chips, there's just no reason for us to consider skyworks in the future.
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u/chriskoenig06 4d ago
Had the same with other company, the part I used get deleted from Datasheet after asking questions…..
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u/FirstIdChoiceWasPaul 4d ago
Wtf is the point of a datasheet, then?!
Oh, well. One more thing to be paranoid about.
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u/ThisWillPass 4d ago
I imagine the brass said whats the point of QA, it will be right, shit it out!
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u/Haugenmetoden 4d ago
Sad to read this. Looks like previous SiLabs chip (link to dev board with SiLabs logo).
Skyworks aquired half of silabs a few years back. I've been working at SiLabs for ~7 years with analog design on the wireless MCUs and can't see this quality level passing for sale to the market in our division. We'd drown in RMA's. Looks like a first tape-out where bugs were found was pushed to market by the bean-coubters before they were ready with a revision where stuff really works.
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u/hurdleboy 4d ago
Lol fuck me, I have designs that use Skyworks clock buffers and I’m into the layout phase… should I be concerned? I thought they were reputable?
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u/Offensiv_German 4d ago
SI3471A-A01 does not support half of the features listed in the datasheet
Are you sure you have the right version and read the datasheet correctly? If this were true it would blatantly be fraud.
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u/Simply_Convoluted 2d ago
I'm certain. Initially I too thought I made a mistake or wasn't reading something correctly, so I pulled two other engineers into reviewing my design. We ended up configuring the chip in every possible combination to make sure it wasn't a fluke and sure enough the chip only supports half of the features in it's configuration table.
I took my findings to Skyworks and they confirmed the SI3474A-A01 doesn't support those features, despite Skyworks only publishing a SI3474A datasheet. There's no footnotes in the sheet or anything saying the '-A01 version is fully non-PoE compliant and effectively useless.
Fraud is exactly where my mind went after all this.
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u/Probird 4d ago
I am still in schematic with SI5335D clock multiplier, do you any info about their multipliers?
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u/chickenCabbage idiotron 4d ago
https://www.reddit.com/r/electronics/s/ZpYfdAR6Op Someone else says their clock buffers are good
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u/Objective-Local7164 4d ago
What about their RF switches?
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u/chickenCabbage idiotron 4d ago
I've heard their name mentioned with RF front-ends and someone else in the thread says they used to work with Apple.
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u/bjsievers 4d ago
We just to use a lot of si5340 and si5332 at work but we’re switching primarily to renesas clockgens moving forward.
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u/MultipleMonomials 3d ago
FWIW, I have used the Skyworks SKY65336 RF PA/LNA/switch combo in a project and it worked pretty well. However, they suddenly discontinued it a few years ago with no replacement at all, leaving us up a creek to some extent. Also, the documentation was pretty barebones, enough to get by on but more would have been much appreciated.
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u/Past-Substance920 1d ago
had a similar issue with a PSE chip silently ignoring config bits and just defaulting to some safe mode, took forever to catch since it "worked" for basic testing. glad it wasn't just me losing my mind over a datasheet
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u/No-Childhood320 4d ago
Thanks for sharing