The AD7148 is designed for use with capacitance sensors implementing 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 （∑-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.