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AD7190/AD7192 Unipolar operation with Buffer

Question asked by damien_d on Feb 13, 2014
Latest reply on Feb 21, 2014 by JohnnyG

Dear All,


I am looking at using the AD7190/AD7192 for an application where I am measuring a ratiometric sensor from 0.3 - 4.7V.  The RC time constant of the output bandwidth limiting filter exceeds the limits of what is specified in Table 22 (p33, AD7192) and thus the use of the buffer is necessary.


The sensor itself satisfies the requirements for the buffer (250mV from the 5V rails).  What should be connected to the AINCOM? Grounding it violates the input minimum, if it is indeed connected to the buffer in unipolar mode.


So what is the preferred means to interface this particular unipolar signal? Assuming the signal is connected to AIN1, what should be connected to AINCOM (or AIN2), and what should be programmed into CH[2:0] in the Configuration Register?


Best regards,