Say I want to reduce noise on the data line for WS2812B led strips. Is it a viable option to use CM chokes to reduce this noise?

According to the docs, WS2812B data speed is 800Kbs. Which I guess translates to 800Khz on the data lines.

I read cm chokes can reduce noise. But I am not sure which ones I should use. Should I get one which has a resonant frequency of 800Khz? Or will that then have the exact opposite effect of what I am trying to achieve?

  • \$\begingroup\$ A CM choke is only good for reducing noise if the data line is differential; is it? If it isn't, you'll just get crosstalk. \$\endgroup\$ – Hearth Jan 16 at 16:57
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    \$\begingroup\$ If it resonates at the same frequency than data bits, that would be quite bad for the data bits. \$\endgroup\$ – Justme Jan 16 at 17:33
  • \$\begingroup\$ The operation of the ws2812s are causing the noise. Ensure your 0V wiring is adequate and inserting a series resistance in the data line to suit. Try 10 to 33 Ohms at a pinch. \$\endgroup\$ – Kartman Jan 16 at 20:57

There are several things to consider here.

First of all, the applicable frequency. It's not depending on the data rate as you think, but rather it's depending on the signal rise and fall times. Usually this frequency is at least 10 times higher than the base data rate dependent clock frequency.

I'm not sure if CM chokes have a specified resonant frequency. They are intentionally lossy components like ferrite beads. You need to select a part that has as high an impedance as possible within the frequency region of operation.

As mentioned in the comments, beware that the data signal is indeed differential or the signal integrity will suffer severely.


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