I have a simple circuit where 5V signal is fed into a buffer, then from the buffer into another device. The buffer is fed 5V by a switching DC-DC. After it’s been off for a while, the buffer works, the signal is recognized by the receiver. This continues for some time, minutes, to tens of minutes. Then the buffer stops working. If I unplug it and let it sit for an hour, it resets back to working for a while until it stops.
Context:
The setup runs on an ebike 36V battery. Theres a hub motor connected to the same battery (via power controller). The signal source is a torque sensor. The destination is a bike computer.
Any idea what could be causing this? I don’t know much about electronics. I learn specific bits to do something but I’m ignorant otherwise. E.g. I know what a buffer does, I understand how it works on high level but I have no clue for example how it could be affected by the rest of the system electrically. My physics intuition here makes me think there must be some charge buildup which dissipates with time when turned off. I’ve no idea if this is remotely valid, or if it is how to fix it. Any ideas are appreciated!
litchralee@sh.itjust.works 2 days ago
When the buffer gets into this glitch scenario, is the output stuck at high or low?
avidamoeba@lemmy.ca 2 days ago
The output is stuck at low.
The input keeps alternating high/low. I’ve checked by disconnecting it and then measuring it. I’ve also checked by substituting the source for identical brand and model spare unit.
litchralee@sh.itjust.works 23 hours ago
For your edit #2, can you post a schematic of the relevant part of the circuit? It’s a bit hard to imagine how things are arranged, especially where your pull up resistor at the output of the buffer is.
litchralee@sh.itjust.works 2 days ago
If I had to guess, perhaps the buffer circuit is going onto latch-up due to ESD spikes, which is then locking the open drain to conduct, which is why you’re seeing a LOW output.
When in doubt, I suppose you can tack on more decoupling capacitors nearby the buffer’s Vcc.