Perhaps this is a hypothetical question, but I'm not sure,which is why I am asking it.
There are now enough 3.3 v. parts around so that I am using them all the time. But I have an inventory of 5 v. stuff to get rid of, like Nanos and ProMinis. So I am combining both types of parts, and implementing two power supplies if necessary.
So here is the question. I have seen chips damaged when the control voltage on some pin arrives at that pin before the power supply for the chip has come up to supply level. If I have 3.3 v.and 5 v. parts interconnected, fed by separate power supplies, suppose those supplies arrive at full voltage at slightly different times. For example, if I brought 12 v. down through a 7805, and then used that to supply an LM1117 3.3 v. regulator, the 3.3. v. supply would come up later that the 5 v.
So, are there any possible real-world consequences to this, or am I just being paranoid?