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Queries about AD7747

Question asked by WayneQ on Apr 25, 2014
Latest reply on May 8, 2014 by WayneQ

Dear Supporter,


I am using AD7747 in my design. Here are some queries that need your help. I am a rookie in CDC product...

1, in my design, CIN+ is the input and CIN- is floating. In the datasheet, it is said that the range is +/-8.192pF. But in my design, I want to measure the capcitor's range of 0~16pF. Is it OK for AD7747? if so, what change do I need?

2, in the datasheet, it is said that "Any offset in the capacitance input larger than ±1 pF should first be removed using the on-chip CAPDACs. The small offset within ±1 pF can then be removed by using the capacitance offset calibration register." I wonder how to realize for operation?

3, is there any way to improve the measure resolution of AD7747?

4, what is the full range of CAPDAC?


Thanks in advance for your patient help!