The internal LDO voltage regulator on MAX79356 must be enabled, and the DVDD12_REG supply output should be connected to the AVDD12 and DVDD12 supply inputs. Disabling the internal LDO may lead to rare lockup events.
The current sunk by AVDD12 and DVDD12 is sourced by DVDD12_REG and is summarized below: (It can also be found in the Electrical Characteristics Table of the datasheet)
There are no significant thermal benefits to using an external supply and hence the internal LDO should always be enabled on MAX79356