The AD7148 is designed for use with capacitance sensors imple-
menting functions such as buttons, scroll bars, and wheels.
The sensors need only one PCB layer, enabling ultrathin applications. The AD7148 is an integrated capacitance-to-digital converter
(CDC) with on-chip environmental calibration. The CDC has
eight inputs channeled through a switch matrix to a 16-bit,
250 kHz sigma-delta (Σ-Δ) converter. The CDC is capable of sensing changes in the capacitance of the external sensors and
uses this information to register a sensor activation. The external
sensors can be arranged as a series of buttons, as a scroll bar or wheel, or as a combination of sensor types. By programming the
registers, the user has full control over the CDC setup.
High resolution sensors require minimal software to run on the
host processor.