[sdiy] dsPIC CV input protection

[Seb Francis]

harrybissell at wowway.com wrote:
> I don't know what kind of A/D input it is... some are
> switched capacitor in which case adding series resistance can
> lead to serious errors... :^)
>   

The dsPIC datasheet specs a max source impedance of 1K IIRC.  It has a 
S&H buffer with very small capacitor that is charged over a certain 
period.  Personally I am cautious of having a source impedance anywhere 
near this high ... I'll probably connect it direct from an opamp output, 
although I'm considering putting a gently LP filter (small series 
resistor, cap to ground) in between to help with HF noise.

Seb