Quoting Forrest W Christian <forrestc@imach.com>:

> ...
> In an ideal world, I'd just do a 100K and 5.6K... unfortunately the
> 'minimum' input impedance is 10K on the 'f886.
> ...


The input impedance spec is what the PIC "sees", and here, that will  
be 100K || 5.6K (parallel), which is about 5.3K, assuming your  
measured voltage has a low impedance.  (An *ideal* voltage source has  
zero ohms).  So you're good.

AFAIK, you can exceed the input impedance spec, but the A/D conversion  
time goes up.  I've not heard of the 0.1uf for exceeding impedance  
before, but my guess is that it's there to reduce noise, as higher  
resistances are more susceptible to noise.

Cheers,
-Neil.


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