ESP-POE-ISO - Power from both PoE and external 5V regulator via pin headers

[jevans3142]

Hello - apologies for covering a topic which has been covered several times before on the forum but having read a number of posts I am still unclear. The description for the ESP-POE-ISO says that it's fine to have both PoE power and the Micro-USB cable providing power at the same time, but some forum posts imply it's not okay to have both PoE power and external 5V power connected to the pin header 5V pin. Is this okay to do? What's the difference between this and USB power? Is it just the FET (FET1 on the schematic)?

My device has a full power supply with 12V, 5V rails etc from which I want to power the ESP-POE-ISO but I want to also make sure nothing will go wrong just in case it's connected to a PoE switch port.

[LubOlimex]

The big problem when powering from the headers is the chance to have powering over the USB at the same time (which is always when you have micro USB cable attached, unless some modified cable). You should not have 5V on the header and powering-capable micro USB attached at the same time. Else you might either burn the board or damage your computer. This is also mentioned here:

https://www.olimex.com/Products/IoT/ESP32/ESP32-POE-ISO/resources/ESP32-POE-ISO-GPIO.png

Powering from the headers and PoE should be alright just make sure the voltage from the header is solid 5V. Problems might occur if it is, lets say, 5.5V or more and PoE is enabled at the same time.