Is AVCC to be connected to 3V3 or to 5V?

I noticed that in the Apalis IMX6 datasheet Analogue supply pins are meant tobe connected to a 3.3 V supply rail, but on the Apalis evaluation board those pin are connected to 5V.
could you please help me in clarify that?

AVCC should be connected to 3.3V. On the Apalis Evaluation Board, AVCC is supplied by a 3.3V regulator. For more information, refer to the Apalis Carrier Board Design Guide.

Note that on the Apalis Evaluation Board IC1, NCP511SN33T1G is the linear regulator which generates the 3.3V for the AVCC rail.