On Thu, 2005-06-23 at 09:37 +0800, Chen Xiao Fan wrote:
> Look at PICkit 1 and you can use a boost converter
> to do that. You can port Microchip's implementation
> to the 16F870. A boost converter is much better than
> a charge pump and will not really cost more (you
> need an inductor but less diode and capacitors).

Interesting.  In this situation I think charge pumps are "better" as
they don't need the feed back and control to keep them from over-volting
the Vpp pin. 

And the circuit in AN258 seems to be a recipe for the smoke to escape
from the transistor in the boot circuit if the PWM output stops in the
high state (Note I don't write bug free code so anything is possible).

Peter.



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