Automotive-qualified touch controller for car centre panels

July 16, 2013 // By Graham Prophet
Atmel's maXTouch controller family enables single-layer shieldless touchscreen and touchpad designs in car centre stacks; true single-layer shieldless designs reduce system complexity, lower overall cost and provide lower power consumption.

For automotive centre stacks, navigation systems, radio interfaces or rear seat entertainment systems, Atmel’s mXT336S is optimised for 7-inch touchscreens, while the mXT224S targets smaller touchscreens and touchpads. The new touch devices are AEC-Q100-compliant and fully automotive qualified and claim superior performance, multitouch, faster response time, more precise touches, robust operation and lower power consumption. The mXT336S and mXT224S devices also provide dedicated embedded functionality that meet current automotive design requirements.

Dedicated firmware and a high signal-to-noise ratio makes these devices 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.

One key requirement for automotive designs is the support for shieldless sensors. "Conventional touch controllers are unable to handle LCD noise, so an additional shield layer is required to prevent noise coupling," said Stephan Thaler, Atmel Marketing Director for Automotive Touch Products. "Thanks to the noise handling and filtering capabilities of our new automotive-qualified maXTouch devices, shields are no longer required, and designers can use single-layer sensors instead of dual or triple layers, which are typical in many current applications. By eliminating an additional layer, designers have a thinner stack which reduces the overall system complexity, lowering the overall cost and power consumption, and resulting in higher product yields during production."

The mXT336S/mXT224S devices support touch detection, up to 10 simultaneous touches, touch size reporting, single- and dual-touch gesture calculation, communication of X/Y positions, gesture support, and the ability to eliminate unintended touches. Users can perform multi-touch gestures (pinch, stretch, etc.), while unintended touches are rejected, such as a resting hand on the screen. All these key features bring the smartphone experience into contemporary cars.