I'm using a third party module in my design which includes a TI LM3281 to regulate from 5V to 3.3V DC.
That part of schematic is straightforward, shown below:
The module vendor seems to imply we can supply the module directly to the 3.3V net from a pin directly connected to VDD33 above.
However there is some confusion if this is possible or not and some users apparently already damaged the module for operating it like that (regulated 3.3v supply to VDD33, while +5V input floating) but it works fine for others. It does seem bad practice at the very least.
Is it true operating the circuit by feeding an externally regulated 3.3V into VDD33 while Mode, EN and Vin are floating can damage this circuit?
If it does cause problems can you suggest a solution to enable powering it safely from either ~ 5V or externally regulated 3.3V? Keeping current consumption as low as possible is extremely important, hence why we'd like to power from the 3.3V pin and avoid the bypass mode.
I know removing R10 zero ohm resistor would be the best option but this is an educational system so asking users to solder/desolder SMD resistors depending on how they power it is not possible.
Thank you
