AVR-Chat

You can exceed it all you want, but you'll get inaccurate results.  The 
problem is with an RC cap charging time constant.  Higher impedances 
will  slow that charge and you'll get "lower" numbers than you should.  
I like to feed the ADC with an OpAmp, a very low impedance there.

DLC

On 2/5/10 12:37 PM, Steve Hodge wrote:
> The Atmel data sheets, at least the ones I'm dealing with, say the "ADC is
> optimized for analog signals with an output impedance of approximately 10 K
> or less".   Does anyone have any experience about how much you can exceed
> this 10 K?
>
> I have a simple voltage divider that I'm reading the voltage from and I'd
> like to minimize current consumption so I'm wondering if this can be
> increased to, say 15 K or 20 K (or more?), without much detectable effect.
>
> Thanks, Steve
>
>
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-- 
Dennis Clark
TTT Enterprises