Bob Ammerman wrote:
> In any case your circuit should probably be:
>
> Resistor +Vdd to ADC pin.
> Same value resistor from -Vss to ADC pin.
> Series resistor and capacitor between source signal and ADC pin.
>
> I'll leave appropriate values for someone else to calculate. In order
> to do so we need to know more about your signal source.

The two dividers can be 20Kohms each.  That presents a 10Kohm load in series
with the cap.  The -3dB rollof point at 2Hz is then 8uF.  Depending on the
settling time you can tolerate on startup, 20uF would work be mostly out of
the way of a 2Hz signal.  The -3dB point of 10Kohms and 20uF is 800mHz.
20uF ceramic caps at this voltage range are readily available.


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