Introduction
The AT42QT1111 (QT1111) is a digital burst mode charge-transfer (QT™) capacitive sensor driver designed for any touch-key applications.

The keys can be constructed in different shapes and sizes. Refer to the Touch Sensors Design Guide and Application Note QTAN0002, Secrets of a Successful QTouch Design, for more information on construction and design methods (both downloadable from the Atmel website).

The device includes all signal processing functions necessary to provide stable sensing under a wide variety of changing conditions, and the outputs are fully debounced. Only a few external parts are required for operation.

The QT1111 modulates its bursts in a spread-spectrum fashion in order to suppress heavily the effects of external noise, and to suppress RF emissions.