First Product in STM's QST Family of Capacitive Touch Sensors Launched

Touch-sensitive controls are rapidly becoming the solution of choice to replace electro-mechanical switches as they allow designers to create elegant and attractive, functional and economical user interfaces for a wide range of designs where durability, ease of use and price are major considerations. The QST family of products will allow the easy creation of sealed, back-lit sensing surfaces, enabling manufacturers to dramatically reduce touch-panel costs while also creating dramatic, contemporary interfaces. First in ST’s QST capacitive touch-sensor series, the QST108 uses a pure digital, firmware-based solution that implements Quantum’s patented and field-proven charge-transfer QProx capacitive technology and provides an intelligent single-chip control interface that responds to users’ touch.

The QST108 sensor device allows users to create capacitive touch-panels of up to 8 keys for their product user interfaces, using conventional or flexible printed circuit board. The sense electrodes can be part of the PCB layout or can even be printed using conductive ink, with flexibility in electrode sizes and shapes. The QST108 detects finger touch using an electrode behind a non-conductive front panel made from materials such as glass or plastic. External component count is low, with only one sampling capacitor and one resistor per channel being required.

“QST provides a solid-state alternative to mechanical switches, allowing significant product differentiation with proven, low risk, robust technology,” said Youssef Benmokhtar, Director for the 8-bit Business Unit with ST’s Microcontroller Division. “Product designers will be able to easily and rapidly develop contemporary user interfaces in a cost effective way.”

QST devices require no production line or user calibration. They incorporate sophisticated drift compensation, auto-calibration, noise filtering and Adjacent Key Suppression (AKSTM) to ensure maximum usability and control integrity. Device configuration allows flexibility in panel thickness, from extremely thin plastics to 10mm or more of glass. QST users also benefit from a range of panel construction methods pioneered and patented by Quantum that are available to ST customers.

The QST108 touch sense controller requires no additional software development and allows different sensing modes selected in firmware and by option resistors. Providing a solid-state alternative to mechanical switches, QST gives great flexibility in user interface design and offers a stable, reliable capacitive touch solution that can be easily soft customized for product designs, and easily re-configured for variants. QST standard solutions significantly reduce the development time and cost, allowing designers to concentrate their creativity on the system design.

Initially available in a 32-pin LQFP package, the QST108 drives up to 8 LEDs. It features PWM capability (pulse width modulation) to drive a beeper output or to control LED brightness. De-bounced touch detection results are accessible through individual outputs or through the I2C interface.

I2C allows the QST108 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.

Over time, ST will expand the QST family with products offering different key counts and new features such as capacitive wheels and sliders. In the near future ST will be offering 1-, 2- and 4-key products and a more complex product offering 7 keys and a wheel or slider. Higher keycounts will be supported using Quantum’s QMatrixTM technology.

The QST108KT6 is sampling now for major OEM customers and will be available to all in Q4 2007. Available in a 32-pin LQFP package, the QST108KT6 is priced around $1.80 in quantities of 10,000 pieces through distribution.