AnsweredAssumed Answered

AD7746 Channels, Conversion Rate, and CAPDAC

Question asked by Yutao on May 12, 2015
Latest reply on Apr 18, 2017 by Wa$iM

Hi,

   I am now using AD7746 on its evaluation board.  With the software provided with the board, it seems that the users can only switch between its two channels in the settings.  Here are my questions:

(1) Can both the channels of the AD7746 be used simultaneously for continuous conversions? If yes, how can this be done? Also, will the conversion rate of each channel be halved as compared to using only one channel?

(2) In the settings, I selected the output data rate to be 9.1 Hz (109.6 ms conversion time).  However, the actual conversion turns out to be slower -- around 7 Hz and varying.  Why is this?

(3) If I want to use AD7746 to measure a capacitance of 50 +/- 1 pF without increasing the noise, is it possible. I know that the current AD7746 can only measure up to 21 pF by using CAPDAC, but is there a way to connect an external CAPDAC to further adjust the measurement range?

   Thanks.

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