How to design Ethernet shield for Portenta? VDDA not available

[marcelrobitaille]

I am trying to design a PCB around the Portenta H7. I can see from the schematic that the Ethernet transceiver is the LAN8742AI-CZ-TR. Reading this datasheet, I know I have to connect the centre taps of the RJ45 magnetics as well as the anode of LED1 to VDDA. However, VDDA is not present on any external connector. Nor is +3V1SW. I am hesitant to just use 3.3V instead of VDDA. The datasheet of the PHY is very clear about this. They use bold and underline.

When pulling the LED1 and LED2 pins high, they must be tied to VDD2A, NOT VDDIO.

Portenta schematic for the PHY:

I wanted to post some pictures of the datasheet here too, but I'm not allowed .

It looks like the Portenta does this incorrectly for the pullups on TXP, TXN, RXP, RXN, and LED1.

What's the best way for me to wire this? Should I just use 3.3V? Should I use 3.3V with a ferrite bead and bypass capacitor?

[rs77can]

I would look at the schematic for the breakout board. It shows what pinds to take from the high density connectors under the board to the ethernet connector.

MTJ-88AX1-FS-TSMT-P-L5-M398AC-WOT-KT Adam Tech | Connectors, Interconnects | DigiKey

This is the ethernet plug they use - the vision shield schematic should have the part number for one in a horizontal orientation.

In the schematic, the power to TCT is 3.3V

[marcelrobitaille]

Thanks for the answer. That's what I ended up doing. I still wonder why they used this design instead of following the datasheet.