I stated 3.3V to be the minimum, simply because I couldn't find a minimum specification. What's the minimum Vcc at which the Pro Micro still works in your opinion?
But I do understand those figures (3.3-6V) correctly in that both
- 3 pcs. AA rechargeables (3x 1.2-1.4V = 3.6-4.2V) or
- 3 pcs. AA alkalines (3x 1.5-1.65V = 4.5-4.95V)
would actually work?