I’m using Sparkfun Qwiic Endpoints to connect a Raspberry Pi sytem to a set of six I2C sensors each on 20m run of CAT6 cable. The Pi end is running on 3.3V supply with the ‘line side’ running on 5V which is then dropped to 3.3V (regulator) at the far end to power the sensors. The system is running very well.
My query is in relation to what would happen if a user inadvertently connected one of the CAT6 cables to a regular Ethernet socket - for example, on a PC or on a IP router or switch (possibly an Ethernet device with PoE). What damage, if any, might result to the Endpoint or to the Ethernet equipment?
Eh, the voltage considerations on these products are among the most difficult to parse out… I’d say run through this https://learn.sparkfun.com/tutorials/sp … 1615791300 and see if you might be able t discern what would happen
PoE isn’t mentioned at all in the guide, so I believe they didn’t account for that type of situation :-/ It might burn up a voltage regulator, it might do nothing
True POE works by sending 48V between the pairs. “Poor man’s POE” does similar but usually 12V, though sometimes it puts it between the two lines in a pair. In any case, the datasheet for the PCA9615 shows a max of 5.5v between any pins that it specifies (not this case but I would guess it is the same since they probably have the same ESD diode structure on each of the pins), it would most likely toast the chip, probably in a rather smelly fashion.