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AD637 rms-dc converter, peak value of ac ripple and dc error formula

Question asked by usaghi on Jun 22, 2012
Latest reply on Jun 25, 2012 by jstaley



As a local distributor, we have asked questions from a customer, in regards to AD637.

It's datasheet Rev.K, at page 9, it shows some descriptions about averaging time constant.

Here, the peak value of the ac ripple is shown by following calculation,

peak value of ac ripple.bmp

and dc error is shown also by following.

dc error.bmp

The customer's questions are,

a) What do you indicate by words "reading" ? We're assuming both of them may be RMS value which is "read" from Vout, but please confirm.

b) Do you have any theoretical/rationale background behind these numbers of "6.3" and "6.4" ?

   They seem to be close to 2 x Pai, or it may be related to any theory in Gaussian distribution ?  

   Or Are they numbers which observed/determined experimentally on actual devices ?


It would be very much appreciated when you help us even briefly showing what they are.


Best Regards,