Is there a way to protect the data line against transient voltage? I’m building a light that’s kind of modular, I have a led strip cut in pieces that have connectors and magnets that keep them in place once connected. After hot plugging them a few times, some had their first or last led burnt(not visible by eye, but data either stops at first led or is not passed to the next strip connected). I have already TVS diodes in place for the current, but left the data line unprotected as I don’t know whether the diode would interfere with the protocol, mess it up etc. Does anyone know what I can use? It would not be a deal breaker not being able to hot plug, but a nice feature to have if there is a way.
I am a very rusty EE. This circuit seems to be for an AVR input, showing a TVS on a signal input. There’s also a RC low pass in front of it, which will attenuate your high frequency content (the sharp edges of the signal’s square wave). You might be able to leave that off or size them appropriately. In an RC, the low pass -3dB point is given by f = 1/(2 * PI * R * C), and WS281X operates at 800Khz.
Do you think I can get away with just the diode? I have very limited space. I’m using SK6812 btw, but they are also rated at 800khz if I’m not midtaken.
I can only find diodes rated at 6.8v, would I be ok with that?
I think it would be fine to leave off the RC filter stage, but I am honestly out of my depth. I’ve hot plugged a few strips probably a couple hundred times on my desk and not experienced what you were reporting with first or last pixel failures (well, except for copper traces and solder points failing from repeat strain). If anyone else has opinions, I’m all ears.
My guess is that a single resistor on the data input would do a lot to prevent damage. Most ICs (including the addressable LEDs I can remember) will have tiny built in diodes that do much the same as TVS diodes, but aren’t designed to handle large currents - such as might happen if you had a power disconnection and data line was driving high - trying to power the rest of the circuit via the data input pin. A large value input resistor will limit the current to values that won’t cause damage.
If you want more, I’d add a pair of diodes after the resistor: one from GND to data, one from data to positive. Maybe 1k-10k resistor.
