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Driving an AD7626

Question asked by ChrisL on Jul 19, 2013
Latest reply on Jul 23, 2013 by jcolao

I'm trying to reconcile the AD7626 datasheet with the Analog Dialogue "Front-End Amplifier and RC Filter Design for a Precision SAR Analog-to-Digital Converter".

 

The article suggests "that external capacitor be relatively large - a few nanoFarads" but the datasheet suggests a 56pF cap. The only way I can see them both being correct is for the CDAC of the AD7626 to be ~560fF. This value seems very small and I can't confirm it since the input capacitance isn't in the datasheet.

 

Please help me reconcile these seemingly conflicting requirements.

 

Thanks

 

BTW, for anyone else finding this, there is another very good EZ thread here on driving ADCs.

http://ez.analog.com/message/38411

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