Would you use WS2812 (and friends) inside a product? - Page 1
Forum section: electronics / projects

author: DavidMenting
author_rank: Contributor
timestamp: June 29, 2016, 08:35:29 am
content: A bit of background: I'm working on a product that requires a semi-large number of RGB leds (~24) that will be behind silicone buttons. So far, I've prototyped using WS2801 18-channel RGB led drivers and surface mount RGB leds. The drivers are fairly large and routing between them and the leds isn't trivial.Smaller 3.5x3.5mm variants of the WS2812 RGB leds with integrated driver seem to be popping up, specifically the WS2852 and SK6812mini. They seem geared to led strips and led matrices but would fit nicely into the silicone buttons as well.Would you design WS2812 or these smaller variants into a low volume commercial product? Any downsides? Anything to look out for?And more specifically- How is the reliability of these compared to 'normal' surface mount leds and separate drivers?- Does using these smart leds have implications for radiated emissions? How do I minimise those?Thanks!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 29, 2016, 08:48:42 am
content: I've seen major quality issues on both WS2812 and AP102 type LEDs, out-of-the-box failures in the former and both initial and failures over time on the latter - I wouldn't consider using them in anything that needed to last a long time without any failures.I never got round to doing a post-mortem on the failures so can't comment on whether it's a chip or packaging/bonding issue.I'm looking at a project now for which white APA102s would be absolutely perfect, but just can't risk using them as it's a permanent installation.It's quite possible that there are good ones out there, the problem is knowing what you're getting. I'm told it is possible to buy direct from Worldsemi but no idea if this would be any better ( or if they sub out the LED/die assembly to random places)

author: mrpackethead
author_rank: Super Contributor
timestamp: June 29, 2016, 08:52:26 am
content: World Semi Chips are possibly the most copied, cloned and mislabeled devices in the led industry. ( I'm in this game and buy millions of driver ICs ).If you get genuine ones, then you are possibly ok.. If you get the other 80% of them, then you are just going to get so much trouble...

author: DavidMenting
author_rank: Contributor
timestamp: June 29, 2016, 08:56:16 am
content: @mike: I saw your post on WS2812 reliability athttps://www.eevblog.com/forum/projects/ws2812b-leds-reliability/and you stated that you're seeing a 2% DOA rate. In the same thread, user Wilksey replies that that is a normal rate for any led manufacturer. I know you build a lot of led installations - are you seeing this differently?I wouldn't mind doing a burn-in test on every board, but having regular failures after that doesn't sound like a nice idea.@mrpackethead: any suggestions for rgb led drivers that are reliable and affordable?

author: chris_leyson
author_rank: Super Contributor
timestamp: June 29, 2016, 09:54:11 am
content: Recently put some WS2812s into some test gear and never had a problem with DOA parts but you have to watch out for serial PWM timing if you are going to use a micro controller to drive them.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 29, 2016, 09:59:25 am
content: Quote from: DavidMenting on June 29, 2016, 08:56:16 amPretty sure those were fakes/rejects as there were also cosmetic issues. If 2% was the going rate it wouldn't be viable to make LED strips, or pretty much anything.

author: Fungus
author_rank: Super Contributor
timestamp: June 29, 2016, 10:41:43 am
content: 2% DOA sounds wrong. If that were true it would be impossible to manufacture LED strips.Power-on needs to be done very carefully. Putting any sort of voltage on the data pin with no power on the Vcc pin will kill them instantly, eg. if you disconnect the LED power supply while the Arduino is still sending data. Adding a resistor in the data line may help, it doesn't happen with the older 6-pin packages.

author: DavidMenting
author_rank: Contributor
timestamp: June 29, 2016, 03:28:33 pm
content: So if I understand correctly, these chips either get killed during soldering or during (un)plugging, or by having a batch of fakes? Would that make it any worse than, say, a separate WS2803 and RGB led combo?

author: Gavin Melville
author_rank: Contributor
timestamp: August 15, 2016, 08:13:07 am
content: 2% failure rate would have been great. Try more like 10%. In the end I could spot failures that hadn't failed yet by eye. They were 70% moisture failures, visible around the periphery of the plastic to silicon rubber seal. They were all bagged until placement, but not baked before placement.The rest were failures where the chip fell off the "heatsink". Failures quickly followed.In general they all worked at first light, give or take a percent or two. Start cycling them 1 minute of white, one minute of black. Failures en mass.In the end I wrote off 15,000 of them. Sigh.

author: Dubbie
author_rank: Unknown
timestamp: August 15, 2016, 09:50:00 am
content: Good timing with this thread. I'm trying to figure out currently how to do a 550 led array for a reasonable cost. I just can't get anything else to come out as cheap or as high performance as an array of ap102's does anyone have any suggestions here?Sent from my phone using Tapatalk

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 16, 2016, 06:58:55 pm
content: I've been involved with 2 big projects using hundreds of meters of apa102 type LEDs - both had many issues, both DOA and fails over time.I think the bottom line is these are made as cheap as possible for non-critical applications, and AFAIK there isn't an option to get better quality ones for a higher price. I wouldn't consider using them for a permanent installation.

author: Dubbie
author_rank: Unknown
timestamp: August 16, 2016, 09:38:02 pm
content: Grrr, looks like I am going to be stuck with tons of multiplexed 16 channel LED drivers...

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 16, 2016, 11:50:14 pm
content: Quote from: Dubbie on August 16, 2016, 09:38:02 pmYou get what you pay for....

author: IMI4tth3w
author_rank: Contributor
timestamp: November 08, 2017, 09:57:03 pm
content: Wanted to bump up this topic again. Looking into the differences in the addressable vs tradition rgb leds for our amusement machine application. It will contain around 100-150 in most cases, some rare cases up to 256.Are there still issues with the quality of the addressable rgbs such as the ws2812b and ws2813b?We are looking to have high reliability with our machine and ideally not have any failures for at least 5 years. Also ease of replacement is a factor as well as availability of the replacement parts 5-10 years down the line. And of course there's cost.The cost difference between the addressable and the traditional with a separate driver chip is surprisingly huge, with addressable leds being significantly cheaper. Going addressable would be a great way to cut cost on our machine. But as far as doing warranty work, some of my coworkers worry that the ws2812b with their unique 1 wire interface will be gone completely and there will be none available to do warranty work.What do you guys think? Should I worry about availability of the addressable leds in 5-10 years? Is the quality of the ws2812b's a thing of the past now?Thanks

author: DavidMenting
author_rank: Contributor
timestamp: November 09, 2017, 09:53:05 am
content: It's still a bit of a gamble. I wouldn't count on the availability of these leds 5 years down the line, simply because the manufacturer does not guarantee availability. Probably your best bet is to contact Worldsemi directly with these questions.We chose to go for the SK6812mini despite the warnings. The low placement count, ease of routing, low emi (no long traces switching high currents!) and low cost were main factors for choosing them. We're making sure we have plenty of replacement pcb's for when repairs are needed.We had some issues with failing leds, but that was due to soldering leds that had been from an opened package. Apart from that, we haven't had any issues with the leds, but there is only a few months of data to back it up.

author: Fungus
author_rank: Super Contributor
timestamp: November 09, 2017, 12:01:20 pm
content: Quote from: IMI4tth3w on November 08, 2017, 09:57:03 pmI don't think there's any reason to believe they're less reliable than any other LED/driver combination.One caveat is that if one of the chips goes down then all the LEDs beyond it in the chain can stop working. On the other hand I've never seen it happen personally. I have managed to kill the first LED in the chain a few times by applying a voltage on the data pin before the LED power supply was fully powered up. Watch out for that one, and put a resistor in the data line just to be sure.Quote from: IMI4tth3w on November 08, 2017, 09:57:03 pmOnly the manufacturer knows their production schedule. OTOH they've sold an awful lot of these LEDs, they've become something of an industry standard.

author: miceuz
author_rank: Frequent Contributor
timestamp: November 09, 2017, 08:42:42 pm
content: I have used ws2812 in a low volume product. We have done several 30-ish unit batches and used about 24 leds per unit. First batches were totally fine and later ones had problems - probably due to moisture when I think about it. I think PCBA house has opened a reel and left it on the shelf till we ordered another batch.

author: IMI4tth3w
author_rank: Contributor
timestamp: November 10, 2017, 10:30:12 pm
content: Thank you for the responses.I've emailed world semi to see if I can get some statistical process control data but we'll see if that actually goes through.What I'm understanding so far is that it seems that the biggest failure comes from mishandling, not poor manufacturing? I've got an led light strip with a bunch of ws2812b leds and have been intentionally been rough with them and haven't been able to kill one yet. (obviously not intentionally putting voltage where it doesn't belong as i know well what will happen then..)I'll try and keep you guys updated as well if i hear anything back from world semi.