8.2.4.1 Supply Order

VDDIN and VDDANA must have the same supply sequence. Ideally, they must be connected together.

VDDIO can rise before or after VDDIN and VDDANA. Note that VDDIO supplies the XOSC, so VDDIO must be present before the application uses the XOSC feature. This is also applicable to all digital features present on pins supplied by VDDIO.