Minimize battery consumption on a 18F2550

[amgen]

from the data sheet for 18f2550. the diode pointing to vcc holds the voltage at the pin to 5 volts (or the supply voltage) as long as the current is under max-rating, generally 25ma. So limiting current way below that is safe operation. Your 78xx volt reg will keep the vcc voltage to the 5 volts.

data sheet from 16f device shows the diodes in the pin input.
don