Posted on February 02, 2016 at 22:40> And if I want to use VDDA as the reference voltage (and not use the internal), do you think I can just tie VREF+ to VDDA?
Of course you can - it's what ST does on smaller packages, anyway, inside the package.
> What would the consequences be -- some potential noise on VREF?
Noise and fluctuations (which at the end of the day is the same, at different frequencies). Absolute precision can be checked/compensated using the internal reference.
VDDA does not source heavy logic - that's what VDD is for - so it may be almost as good as a separate external reference, if VDDA is properly designed for. Don't forget about quite grounds, too, especially VSSA. Have you consulted that appnote?
Also be prepared for quite a significant noise in the ADC itself. Read thoroughly the values given in the datasheet, these add up to the proportion of VREF noise.
> Pardon my ignorance, this is my first foray into digital.
But, isn't ADC as analog as it gets, in the realm of microcontrollers? ;)
Jan
