Touch Sensor Chip Integrates Touch Slider or Wheel with Seven Extra Keys

In both instances, absolute position is detected. The seven additional touch keys, which can be independently tuned for sensitivity simply be changing an external capacitor, allow the QT1106 to be the basis of a complete user interface for any application in which a mechanical wheel, slider or switch would normally be used. However, the charge transfer touch technology costs less to implement, allows greater design freedom, is physically robust and has no wear-out mechanism. The device has a 5-wire SPI interface.

Target applications include mobile phones, remote controls, small kitchen appliances, home audio, portable media players (including MP3 players) and lighting controls.

Quantum’s charge transfer (QT) sensing technology allows electrodes, which can be made from any conductive material, to project sense fields through any dielectric – most commonly plastic or glass. An approaching finger causes a change in the sense field that registers as a touch. Unlike traditional capacitive touch sensors, QT sensors feature automatic self-calibration for life on power-up. This eliminates long-term drift problems due to build up of contaminants on the touch surface or changing environmental conditions. A flexible low power mode enables system designers to optimize the trade-off between response time and power consumption. QT sensors use spread-spectrum burst technology to provide better than 20V/m noise rejection and the devices feature a sync mode to enable synchronization with other similar parts, or with an external source, to suppress interference.

Quantum’s patented adjacent key suppression (AKS) technique prevents multiple keys responding to a single touch. It compares the relative signal strength from each key within a group and suppresses touch detections from those keys that show a weaker signal change than the dominant one. Close spacing of keys can therefore be used, without introducing touch errors.
The QT1106 comes in an RoHS-compliant, 32-QFN package and it operates from a single 2.8V to 5.0V supply.