I checked my circuit and it was just a diode in series from the output of the regulator into the raw input of the pro mini . This isolated the upstream circuit from the USB fed 5 vdc to to pro mini.
I would think ( I am not an engineer ) that if you did the same in line diode from your regulator out to the Vin / Raw in to the board you should be protecting the USB for you computer .
I would appreciate any thoughts on this from more experienced members , I do appreciate their insight and advice.
BobD