As the title suggests, PoE + Pico + W5xxx-io boards were produced.

The circuit and characteristics are consistent with the article below, so please refer to the article in the link below.

https://hackaday.io/project/188560-what-is-poe-my-tough-poe-development-process

The concept is to develop a development board that can be developed by combining MCU and PoE in any way on the W5xxx Chip.

The existing PoE circuit will be developed by installing WIZnet's io module, removing the connected pins, and connecting them with MCUs

https://docs.wiznet.io/Product/ioModule

However, the W5500 is not compatible with the W5500 because the Bias voltage of the Rx and Tx lines is different from the other chips, and only W5100S-io/W6100-io is compatible. I think it would be good to make it possible to select with a header jumper in the future.

This is how the circuit was constructed. I tried to make it possible to do W5500 Select somehow, but I decided to postpone it until later due to the situation was difficult.

And first, the main MCU will be Pico's RP2040. Of course, the pins are pulled out so that other MCUs can do it comfortably with jumpers.

(The W5500 has different Rx and Tx modes, so CT classification is required, but there are not many RJ-45s on the market where CT is separated while satisfying both PoE Mode A and B...There is, but supply and demand are not available.)

The board came out pretty like this. It's a little big, but it has the advantage of not arranging the back.

The board arrived and assembled. As a result of the experiment, parts that are okay to remove a little were removed. (Related to Noise)

I've done some moves. Last time, I used an electronic load, but there was a problem with low voltage and low current, so I put resistance on it and made it AGING. Both Link and Act LED come in well. The communication works without any problems, and the heat of the elements on the board is okay.

The resistance was experimented by connecting four 20 ohms in parallel to 5V. It runs at about 5W without any problems. I've turned it up to 7W, but when using the Flyback circuit of the switching regulator, the reference power is 5.5W, so I think there will be a problem if I keep turning 7W.