Capacitive Touch Sensors Go All Digital

The QST108 is the first in a series of capacitive touch sensors from STMicroelectronics using a pure digital, firmware-based solution that implements the Quantum Research Group's patented charge-transfer QProx capacitive technology. The device provides an intelligent single-chip control interface that responds to the user's touch. QST devices require no production line or user calibration. They incorporate sophisticated drift compensation, auto-calibration, noise filtering, and adjacent key suppression to ensure maximum usability and control integrity. The device's configuration permits flexibility in panel thickness, from extremely thin plastics to 10 mm or more of glass. QST users also benefit from a range of patented panel construction methods from Quantum that are available to STMicroelectronics customers.

The QST108 requires no additional software development and allows different sensing modes selected in firmware and by option resistors. Initially available in a 32-pin low-profile quad flat package (LQFP), the QST108 drives up to eight LEDs. It features pulse-width modulation capability to drive a beeper output or to control LED brightness. De-bounced touch detection results are accessible through individual output or through an I²C interface, which enables the sensor to communicate with the application host controller. User-configurable parameters and control functions such as detection threshold, detection integrator, sensor recalibration, low-power mode activation, AKS mode, and key states and configuration are accessible using simple I²C commands.