AnsweredAssumed Answered

EVAL-AD7747 or EVAL-AD7147

Question asked by Rock on Mar 1, 2012
Latest reply on Apr 19, 2012 by Holger


I have been doing some capacitance tests for our cantilevers. basically, the cantilevers herein are the capacitive cantilever which has one electrode grounded and another electrode is located on top of the cantilever. What I would like to know is the capacitive change while different excitation frequency change on the cantilever. The distance between two electrodes will change while the excitation frequency is changing. The static capacitance value of the cantilever is around 8 pF and the change should be +/-4 pF. However, the excitation frequency I would expect has a range from 10 Hz to 600 Hz which is much higher than the update frequencies of both of chips. Therefore, I though they may not be able to pick up the correction capacitive values.


Another question is the cantilever should be connected to the evaluation board. The EVAL-AD7147 does not compatible with the the capacitive sensors directly connected to its inputs. In contrast, EVAL-Ad7747 does have the connection pin which the sensor can be connected directly. Am I right?


Finally question is I require a graphic results at the final stage. Can I export the measured results from both of them or either of them?


I appreciate any suggestions, comments and help.


Many thanks,