I'm trying to understand the datasheet for the AD5535B DAC. I think I can understand why there would be a DVcc (digital Vcc) and AVcc (analog Vcc) to prevent digital switching noise to enter the analog circuitry and to allow maybe 3.3V digital signals. In addition, there is a high voltage input Vpp. However, on the analog side we find both an AVcc and V+. They have the exact same voltage ratings. The datasheet has only this to say,
If the number of supplies must be reduced, bring all supplies back separately and make a provision on the board via a link option to drive the AVCC and V+ pins from the same supply.
I guess this means that they recommend to still have separate power supply connections to the eventual PCB, but allow them to be tied together if needed. But that still gets me no closer to why one would want them separate at all.
What is the explanation for these two separate supplies? Why should I bother? The manual for the evaluation board just specifies to use a single power supply for V+ and AVcc.