We have a design where there are beads feeding each of the supplies from a signal switching regulator (buck). For a particular customer we need to power several bright LED's from the VDDD bead because there is no connector on the board that has the direct regulator output. This will cause additional drop across the VDDD bead when the LED's turn on, so VDDD will be at a slightly lower voltage than VDDA and VDDR. What is the maximum voltage differential between the three supplies? We have a nominal 3.3 volt supply so is the differential basically the drop to the dropout level of the internal on-chip regulators?
VDDA must be the highest voltage and be less than 5V, 3.3V is ok..
VDDD must be greater 1.8V.
When VDDD changes some analog components as capsense, ADC, DAC or comparators might fail or deliver strange results.