Yes, I would ideally like to operate the IC at the highest Vka available through Vcc.
Leaving good head room for IC tolerance.
If you start with a high voltage needing interface with Arduino.
Say 100v Max.
Divide to the highest reliable Vka, to amplify accuracy at 5v level.
.4% @ 20v = .04% accuracy after voltage division to 2v.
The final voltage on input of Arduino would still be of Max 5v.
I could be wrong with this basic logic, let me know.
Thanks
Wrong.
You do not increase accuracy when you go through a voltage divider. At best you maintain accuracy if you have perfectly matched resistors in the divider. But in most cases your initial accuracy is further degraded by the precision of the resistors in your divider.