Hello, We design capacitive tactile sensors from elastic materials. Traditionally we have been using an Analog Devices AD7746 to read changes in capacitance but would like to move to higher sampling rates for our applications. This chip has been great for handling floating capacitors though.
From the datasheet, it is unclear if the FDC2xxx chips can measure floating capacitances. From Fig. 55, it looks like they might be able to if we hook them up in a differential configuration (which we have done in the past).
We also often have large resistance between the chip and sensor (up to 10s of kOhm) and that resistance can vary over time. Given the operation of this CDC chip as a resonant circuit, I assume a variable resistance between the sensor and chip would have significant impact on the measurement.
So, in summary, 2 questions:
1. Can I measure a non-grounded capacitive sensor with TI's CDC chips?
2. Can TI's CDC chips (and especially the FDC2xxx series) handle a variable resistance between the chip and sensor?
Thanks.
