AVR-Chat

Do you really need accuracy or do you actually need resolution?

With 16 bits, your least significant bit will be just over 15 microvolts 
for a 1 volt full scale input.  This would equate to 45 microvolts at 
2.5 volts FS.  At the very least, way down in the mud for most applications.

If you use the 10 bit A/D converter of the AVR, which is very linear 
from my experience, you can get more accurate results with higher 
resolution by using an averaging filter.  There's a good app note for 
using a moving average filter at the Atmel web site.

Don't allow yourself to confuse accuracy with resolution.  Unless you're 
absolutely anal retentive about such things as circuit layout, thermal 
isolation and compensation, and even solder junction equalization you 
can bite your own tushi by insisting upon 16 bit accuracy when it isn't 
necessary.  If your LSB is that far down in the mud a gust of cool air 
from an air conditioner turning on can throw your measurements off.


REB



magzky02 wrote:

>The internal ADC of my mega16 is 10 bit. But i want a more accurate 
>one. about 16 bit or better. Anyone can suggest a 16 bit ADC with 
>either SPI or i2c interface. seem some from TI but i want to consideer 
>suggestion first before deciding. the IC should run at 3.3V.
>
>regards
>mago
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