> I have to design a simple circuit using the ADC in AVR AT90S8535.
> I remeber the strong requirements for signal source impedance in PICs,
> but the only info in 8535 datasheet was "RAIN Analog Input Resistance =
100
> MOhm (typ.)". Does it mean that the S/H in 8535 features the internal
> voltage follower or something like this?

This certainly sounds like there is an internal buffer amp with FET input.
That means source impedance is much less of an issue than with PICs, but now
you have to watch the offset voltage and bias current carefully to make sure
your accuracy requirements are met.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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