Capacitive sensing is a low-power, low-cost, 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 low cost and highly flexible system design.
The main challenge limiting sensitivity in capacitive sensing applications is noise
susceptibility of the sensors. With the FDC2x1x innovative EMI resistant architecture, performance
can be maintained even in presence of high-noise environments.
The FDC2x1x is a multi-channel family of noise- and EMI-resistant, 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 noise and
interferers 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 fast sample rate, up to
13.3ksps, for easy implementation of applications that use fast moving targets. The very large maximum input
capacitance of 250 nF allows for the use of remote sensors, as well as for tracking environmental changes over
time, 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, which has integrated active shield drivers.