QMatrix devices are digital burst mode charge-transfer (QT) sensors designed specifically for matrix geometry touch controls; they include all signal processing functions necessary to provide stable sensing under a wide variety of changing conditions. Only a few external parts are required for operation. The entire circuit can be built within a few square centimeters of single-sided PCB area. CEM-1 and FR1 punched, single-sided materials can be used for possible lowest cost. The PCB’s rear can be mounted flush on the back of a glass or plastic panel using a conventional adhesive, such as 3M VHB 2-sided adhesive acrylic film. QMatrix parts employ transverse charge-transfer ('QT') sensing, a technology that senses changes in electrical charge forced across an electrode by a pulse edge QMatrix devices allow for a wide range of key sizes and shapes to be mixed together in a single touch panel. The devices use an SPI interface to allow key data to be extracted and to permit individual key parameter setup. The interface protocol uses simple single byte commands and responds with single byte responses in most cases. The command structure is designed to minimize the amount of data traffic while maximizing the amount of information conveyed. In addition to normal operating and setup functions the device can also report back actual signal strengths and error codes. QmBtn software for the PC can be used to program the operation of the IC as well as read back key status and signal levels in real time. The QT60168 and QT60248 are electrically identical with the exception of the number of keys which may be sensed.
Second generation charge-transfer QMatrix technology
Keys individually adjustable for sensitivity, response time, and many other critical parameters