pic wrote:
> I would not be able to use a diode in series with the 3.3V supply. The
> circuit requires a precision regulated voltage
> and I batches of Schotky diodes would have a spread in Vfwd.

Does the PIC itself need the precision voltage, or other parts operated at
3.3V?

A trick I use sometimes is to isolate the PIC and the rest of the circuit by
giving each its own diode from the power supply, but include one of the
diodes in the regulator feedback path.  This means one of the two (PIC or
other circuitry) get tightly regulated voltage, and the other is off by the
difference in the two diode voltage drops.  This is still well within the
specifications of any digital logic I've ever used.

> Redesigning our hardware, adding diodes and resistors etc
> just so the micro can clear a software programmable protect bit seems a
> lot of mucking around to me.

Do you really need code protection?  Most of the time people seem to
overestimate the competitive value of their binary code.


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