The internal 1.2-V VREG generates VDD12 power from VDDIO. The 1.2-V VREG is enabled by pulling the VREG12EN pin to a low state. When enabled, the 1.2-V VREG internally provides 1.2 V to digital logic associated with the processors, memory, and peripherals of the Digital Subsystem.
When the internal 1.2-V VREG function is enabled, the 1.2 V power no longer has to be provided externally; however, the minimum and maximum capacitance required for each VDD12 pin to stabilize the internally generated voltages are 250 nF and 750 nF, respectively. These load capacitors are not required if the internal 1.2-V VREG is disabled and the 1.2 V is provided from an external supply.
While removing the need for an external power supply, enabling the internal VREG might affect the VDDIO power consumption.