>Can you use pin RA4?  The problem with your circuit as drawn is that
>the 470R resistor is gonna be above the PIC supply voltage when you want to
>operate from 3.3V.

The 470 is a typo.  It should have been 47K.  This gives just enough
trickle to bring the circuit up in 5V mode (slowly).

>Is the 3.3V supply derived from the 5.5V supply?  How much current do you
>actually need at both the 3.3V and 5.5V operation.  How much drop can you
>tolerate?

I need 250mA minimum available.

>If the whole circuit is operating from a single supply that *changes* from
>3.3V to 5.5V, you could just manipulate the Vadj pin on your voltage
>regulator.  This works for both 317 type linear regs as well as LM2575 type
>switchers.

Both are coming from a 13-16V supply.  They can be two regulators, or one
switched between two values, or a 5V supplying the 3V.  Doesn't matter.

Andy

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