Capacitive sensing is a low-power, high-resolution contactless sensing technique that can be applied to a variety of applications ranging from proximity detection and gesture recognition to remote liquid level sensing. The sensor in a capacitive sensing system is any metal or conductor, allowing for a highly flexible system design.

The main challenge limiting sensitivity in capacitive sensing applications is noise susceptibility of the sensors. With the FDC2x1x resonant sensing architecture, performance can be maintained even in the presence of fluorescent light.

The FDC2x1x is a multi-channel family of high-resolution, high-speed capacitance-to-digital converters for implementing capacitive sensing solutions. The devices employ an innovative narrow-band based architecture to offer high rejection of out of band noise while providing high resolution at high speed. The devices support a wide excitation frequency range, offering flexibility in system design. A wide frequency range is especially useful for reliable sensing of conductive liquids such as detergent, soap, and ink.

The FDC221x is optimized for high resolution, up to 28 bits, while the FDC211x offers a fast sample rate of up to 13.3kSPS for easy implementation of applications that use fast moving targets. The large maximum input capacitance of 250nF allows for the use of remote sensors, as well as for tracking environmental changes over time such as temperature and humidity.

The FDC2x1x family targets proximity sensing and liquid level sensing applications for any type of liquids. For non-conductive liquid level sensing applications in the presence of interferences such as human hands, the FDC1004 is recommended and features integrated active shield drivers.