XE216-512-TQ128 Datasheet
P.21
If the PHY supports a 3.3V IO voltage, then a 3.3V supply can be used for VDDIOT.
P.23
The signal description (Section 4) specifies which I/O is powered from
which power-supply VDDIOT powers the RGMII IO pins, and must be provided
with 2.5V.
P.29
Both VDDIOT 3v3 and VDDIOT 2v5 characteristics.
P.77
VDDIOT has a 2.5V supply.
Is it possible using 3.3 V supply?
Must VDDIOT be powered even if RGMII interface is not used or it can be left unconnected ?
VDDIOT voltage
You can power VDDIOT with 3V3.
I would not leave it unpowered, most likely you will use some pins powered by VDDIOT anyway.
I would not leave it unpowered, most likely you will use some pins powered by VDDIOT anyway.
We don't need VDDIOT. Is it good for CPU if VDDIOT will be left unpowered?
Not connecting power rails in the general case is always a bad idea and can lead to undefined behaviour unless explicitly stated by the manufacturer that you can leave it unconnected. So I would just connect them, its only two pins only and they are adjacent to each other too.