> It should also be possible to charge-pump a low voltage PIC's pin
> to make 5V (or at least > 4.6V I think) for the LCD's V+ if running
> on a couple of AAs.

Rule of thumb is a no load supply will get to within 2 diode drops of pump
Vdd with silicon diodes and a single stage pump. ie about 4v8 with 3v Vdd.
Your two AA's will drop below 3v fairly soon in their life.

Using Schottky small signal diodes (BAT85 etc) will give you about Vdd- 0.5v
boost or about 4v5 for Vdd = 2v5 or more. Synchronous switches and multiple
stages get you more voltage at the cost of complexity (and diminishing
returns per stage)


        RM

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