Can the VDD_MPU power supply be powered with a fixed 1.325V?
The power supply user's guide (SLVUAB1) describes that the VDD_MPU power supply is powered with a fixed 1.325V for 1-GHz operation.
Discrete Power Solution for AM437x
http://www.ti.com/lit/ug/slvuab1/slvuab1.pdf
7 Supporting AM437x 1-GHz Operation
On the other hand, the datasheet (SPRS851C) describes that the VDD_MPU power supply is powered at 1.1V in the power-up sequencing.
Best regards,
Daisuke