@User: How high a voltage are you looking for? The caravel chip does not have any straight-through (i.e., simple analog) pins; there are either the power domain pins or else they are GPIO and connected to digital circuitry. You can apply up to 5.5V on the VDDA power supply. Above that, the user domain VDDA2 pad might be able to go higher, but it's still connected to a high voltage clamp circuit as well as the pad diodes, so you would want to check whether anything would be overloaded. But it depends very much on just what voltage you're planning to apply to it.