New automotive-qualified maXTouch controllers support shieldless sensor designs

February 27, 2012 // By Paul Buckley
Atmel Corporation has released its maXTouch family for 5 inch to 10 inch automotive touchscreens and touchpads used in center stack displays, navigation systems, radio human-machine interfaces (HMIs) and rear-seat entertainment systems.

The new automotive-qualified devices include the maXTouch mXT768E and the maXTouch mXT540E, which are part of a family known for its superior performance and rich feature set. This family offers unlimited touch identification, fast response time, exacting precision, robust operation and low power consumption.

Dedicated Embedded Functionality for AutomotiveThe mXT768E and mXT540E devices are fully automotive-qualified (Grade 2, AEC-Q100-compliant), supporting a temperature range of -40 up to +105°C. In addition, they provide dedicated embedded functionality that meets automotive design requirements.

Support for shieldless sensors is an important requirement for automotive designs. With maXTouch automotive-qualified devices, designers can use single-layer sensors instead of dual or even triple layers, as is currently applied in many applications. Conventional touch controllers are unable to handle LCD noise, so a shield is required to prevent noise coupling. Automotive-qualified maXTouch devices provide superior noise immunity, eliminating the need for shields. This, in turn, enables single-layer sensor designs for thinner stacks, which reduces system complexity, lowers overall cost and power consumption, and results in higher product yield during automotive systems production. The high signal-to-noise ratio of 80:1 in automotive-qualified maXTouch devices makes them ideally suited for very noisy environments. Since only a high signal-to-noise ratio enables detection of touches with a ‘gloved’ finger, the devices provide full support for gloved hand operation on automotive touchscreens.

The mXT768E/ mXT540E devices also embed single- and dual-touch gesture calculation as well as post-processing algorithms which eliminate unintended touches. Users can perform multi-touch gestures (pinch, stretch, etc.), while unintended touches such as a resting hand on the screen are classified and rejected. These functionalities bring the smartphone experience into contemporary cars.

Additional maXTouch capabilities targeting automotive applications include frequency hopping during burst generation, self calibration, detect integration addressing EMI/EMC requirements and high reliability in harsh environments. With a scan speed of up to 150Hz, design engineers can provide character recognition for alphanumeric inputs to the automotive HMI interfaces, another key feature