AVR-Chat

Hi jim
the atmel company has guarantied vref=2.3v for ref pin,ofcourse i use
1.25v and I dont have problem,but you can use 200x internal gain in
atmega8 and Vref=Avcc,therefor you can't 0.1V for Vref
because the ADC can't work, 

--- MuRaT KaRaDeNiZ <karademu.yahoogroups@onlinefavbar.com> wrote:

> Hello James,
> 
> Some suggestions:
> Choose a voltage reference implementation with minimal noise, since now
> 100uV noise becomes 1bit of the result, and simple voltage
> references/regulators surely have more noise than that. Make use of RC
> filtering on reference voltage. if you use simple resistor divider, do
> not take too high resistor values, since thermal noise in a resistor is
> proportional to square root of resistance value.
> 
> Don't forget to inform us about the results.. :)
> 
> Regards
> 
> Murat Karadeniz
> http://www.onlinefavbar.com/mukas
> 
> 
> -----Original Message-----
> From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
> Behalf Of James Washer
> Sent: Sunday, November 27, 2005 10:16 PM
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] Question on using AVR (Mega8) ADC for low voltage
> measurements
> 
> 
> I need to measure voltages in the 0-50mV range. I suspect the answer
> here is to use an amp to get this to a more reasonable level (say
> 0-2.5V) however I was wondering if it is ok to just supply AREF to 0.1
> volts.. I suspect this is a bad idea, but I wanted to know for sure.
> 
> thanks
> 
>  - jim
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 



	
		
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