The voltage regulators must be sequenced using the power-good outputs and enable inputs to make sure the Vx11 regulator is enabled after the VA19 supply is good. Similarly, as soon as the VA19 supply drops out of regulation on power-down, the Vx11 regulator is disabled.

The general requirement for the ADC is that VA19 ≥ Vx11 during power-up, operation, and power-down.

TI also recommends that VA11 and VD11 are derived from a common 1.1-V regulator. This recommendation makes sure that all 1.1-V blocks are at the same voltage, and no sequencing problems exist between these supplies. Also use ferrite bead filters to isolate any noise on the VA11 and VD11 buses from affecting each other.