I am looking for 64 channel CDC like AD7147. Need of measuring capacitance from 400fF to 10pF
You can refer to this for a list of capacitance to digital converters. Currently, ADI do not have the 64 channel CDC. From the list you might be interested of some parts that may fit your application.
You can do parametric search and short list the products by filtering base from your application.
Thank you very much for your reply. I already went through the parameter search. I think I can use 5 of AD7147 for getting 64 channels. But I was not sure about what to do with second terminal of my sensor if I use AD7147. It do not have EXC pin as found in AD7150.
Also it has base capacitance requirement of 20pF but mine starts from 400fF to 10PF is it okay to add capacitance in parallel with it?
I will be grateful if you can you suggest something with these.
We do not recommend the use of multiple AD7147 devices in one application, they will interfere with each other as their excitation signals will not be synchronised. The AD7147 measures capacitance relative to ground (self capacitance) compared to the AD7150, which measures capacitance relative to a second terminal (mutual capacitance). The AD7147 can offset bulk capacitance up to 20pF and can then measure a varying capacitance value of up to +/-8pF.
Thank you so much Maurice.
I placed order for the evaluation board of AD7150. Do you have any suggestion for using this for multichannel (around 64 channels)
Similar to the AD7147, multiple AD7150 devices operating together could result in interference between devices as their excitation signals will not be synchronised, it is not something we would recommend unless you can build your circuit such that there is good separation and ground shielding between the devices and the sensors of each device. It is high risk. Unfortunately we do not have a 64 channel solution.
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