Cristiano Cesaretto wrote:
> regard the analog to digital converter, page 270 of the 18F4550
> datasheet says: "The maximum recommended impedance for analog sources
> is 2.5 KOhm". Does it mean using a 10K potentiometer is not advisable?

No, that means a 10K pot is the largest you can use and stay within the
recommendation.  This is assuming both ends of the pot are tied to a low
impedance, like Vdd and Vss.

Remember that the worst case output impedance added by a pot is 1/4 its
value.  When the wiper is in the center, it becomes a resistor divider with
1/2 the pot value in each leg.  Those two legs in parallel make the total
1/4 the pot value.


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