Does ESP32-POE-ISO provide "redundant" power?

[sbrudenell]

I understand that with the ESP32-POE-ISO family, it's safe to connect both 5V USB power and PoE.

When connected to both USB and PoE, are the power supplies "redundant"? Will the MCU continue to run if one of them is disconnected? Or perhaps, will it reset, and then keep running?

If USB *does* provide redundant power: What if I have a non-USB +5V power source? Would it be safe to connect this directly to the +5V header as a power input, at the same time that PoE is connected? Would they be redundant in this case? Or is it only safe to connect +5V power input via  the USB socket?

(I also asked this question via support email, but I thought the answer would be more useful in a public forum)

[LubOlimex]

Yes, when using the insulated version - ESP32-POE-ISO - it is safe to have PoE powering and USB powering applied simultaneously. When both are present the POE supply is applied while the USB supply is "blocked", this means that the wattage taken from the USB would be close to 0.

Will the MCU continue to run if one of them is disconnected? Or perhaps, will it reset, and then keep running?

Disconnecting one or the other power source would not hinder the board's operation. It would continue to work seamlessly powered from the left over power source. It won't reset.

Also it is fine to have only one or the other, for example, you don't need PoE switch attached to power and program the board via the USB.

What if I have a non-USB +5V power source? Would it be safe to connect this directly to the +5V header as a power input, at the same time that PoE is connected? Would they be redundant in this case? Or is it only safe to connect +5V power input via  the USB socket?

The +5V pin from the EXT header is usually used for output (to power other peripherals trough ESP32-PoE-ISO), however the board can be powered form it  too (it can act as input). Notice that you should not have +5V power applied to the extension header and have 5V applied to the USB at the same time. This might damage the board or your computer. Remember have either USB or 5V on pin #1 from EXT1 - not both simultaneously! This is mentioned in the top left corner of this image, under "POWER SUPPLY":

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

Just like it is fine to have USB and POE at the same time - it is also fine to have PoE at the same time as external 5V on pin #1 of EXT1. Just not USB and external 5V!