AVR-Chat

I'm also curious, but a cap IS a low pass filter.

Cat
----- Original Message ----- 
From: "dlc" <dlc@frii.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Monday, June 18, 2007 11:00 PM
Subject: Re: [AVR-Chat] Using the ADC to measure the battery supply?


> If the cap is across it then the ADC might not get the correct voltage 
> either.  The ADC relies upon charging a cap inside the module.  That 
> relies upon a certain target RC charge rate, that charge rate also must 
> not exceed the current capacity of the pin.  You are playing a finicky 
> game by using a cap to boost the inrush current to offset the RC time 
> constant.  It might work under some circumstances but since the ADC 
> modules specifically states that you should only be using slowly 
> changing signals on the circuit with low-pass filters that would tend to 
> contra indicate using a bypass cap I think.  Have you used such a 
> circuit successfully before?
> 
> curious,
> DLC
> 
>