Hi all,

I'm working on a motor control circuit using the dsPIC33FJ64MC802

Looking at the ADC specs, the minimum recommended source Z
is 200 ohms, yet I see designs for this PIC with 10k pots (between
Vss and Vcc), which I understand to equal 5k impedance

Comparing the ADC internals with an older chip like the 18F452, the
dsPIC sample cap is signifiantly smaller, 4.4pF vs 120pF, so I would
expect the source Z to be lower. It's 2.5k for the 452

I've used the GP802 for audio work, and unwittingly probably met
spec by buffering the inputs with opamps. At the time I hadn't realised
that the minimum Z was as low as 200 ohms

So, for my own peace of mind and best results, I should be using 500
ohm pots with this ADC ?

TIA

Joe
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