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WS2812 and EMC

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artag:
Has anyone here used WS2812 or similar LEDs in a product that needed to conform to EMC standards ?
There's bot a long wire with a 800kHz data ilne and a bunch of PWM'd LEDs.
They're probably a nightmare to suppress. Has anyone tried ?

srlevitt:
I'm having similar woes. See https://electronics.stackexchange.com/questions/660535/radiated-emissions-from-ws2812-leds
Did you get anywhere?

artag:
Due to production needs my led array is now 13 strings of 11 leds instead of one string of 140 leds. This is unlikely to help the EMC situation but I'm only now starting to make measurements. Unfortunately although I have measurement equipment I don't yet have a calibrated baseline from a test lab.

I read your piece on stackexchange with interest. As I understood it one guy had built a system with no problems but the leds are in an aluminium envelope with holes around each led. I can't afford that, though some sort of aluminium foil housing might be an option. The mechanical designer's face when I ask her to replace a painfully developed plastics superstructure with tinfoil will be a picture thought it might actually be quite good.

langwadt:
you can probably vary the 800kHz to spread it out if that helps

SiliconWizard:

--- Quote from: langwadt on October 16, 2023, 01:31:56 am ---you can probably vary the 800kHz to spread it out if that helps

--- End quote ---

Yes. The datasheet gives a rather wide tolerance on timings (each low/high state +/-150ns), so at least according to the DS, you should have +/-300ns max over one period (1.25µs), which is +/-24%. That's quite a span for spread spectrum.
Of course, that will complicate the code a little bit.

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