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AD7746 - Extending Capacitance Input - Calibration Factor?

Question asked by arrm93 on Jul 8, 2015
Latest reply on Jul 9, 2015 by Stephen_Nugent

So I have read a number of documentation such as the datasheet, the circuit note CN-0129, and the EVAL board doc, but I still have a question about this specific component - AD7746: 24-bit Capacitance-to-Digital (CDC) Converter.


How do I find/calculate the calibration factor stated in CN-0129?  There is a constant GAIN_CAL, which is a factory calibrated constant.  Later in the document, it states it can be calculated.  So I am confused.  Is the number given "24509" (0x5FBD) the factory calibrated constant or a value that needs to be calculated? If it is calculated, how do I do so? If not, what is this constant?

 

Thank you very much.
Best,
Allan

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