I am designing a board to power a WS2815 style LED strip. This strip has three inputs: 12V, GND, Di. This wire -> LED strip will be up to 60ft away from the control board. As such, I want to filter it to prevent common-mode noise on that wire. I will be using 20AWG twisted pair for the 12V/GND pair. I also plan on using a common mode choke. The Di wire will be smaller, say 26AWG.
Due to size constraints, it is not possible to have the Di line in the twisted pair bundle with the 12V/GND, and they will be run next to each other.
My question is, since I am filtering CM on the 12V/GND, do I also need to do anything with the single Di line? My thought is yes, since CM noise could propagate off of my control board, travel on the Di line, and radiate (or noise couples to the Di, and travels back to my control board.)
If I do need to filter it, what options do I have? Other than having a isolated termination on one side of the data line, I can't just have a single CM filtered line of course. I suppose a ferrite or a PI filter with a cutoff above the data transmission speed could also be an option?