Touchscreen controllers address challenges in large automotive displays

By Alex Pluemer, contributing writer

Touchscreen displays like the ones featured in most smartphones are becoming more common in newer model automobiles every year. As touchscreen displays get larger, they can begin to interfere with other automobile functions like car access systems or AM radio frequencies, said Microchip Technology Inc. In addition, the automotive touchscreen displays are also subject to stringent safety and design requirements such as head impact and vibration tests, which result in thicker cover lenses that can impact the touch interface performance. Microchip Technology recently introduced two new maXTouch touchscreen controllers, the MXT2912TD-A and MXT2113TD, to address these issues in automotive touchscreen displays up to 20 inches in size.

Both the MXT2912TD and MXT2113TD controllers include self- and sensor-diagnostic functions to monitor the touchscreen’s functionality and stability and meet the Automotive Safety Integrity Level (ASIL) classification index as defined by the ISO 26262 Functional Safety Specification for Passenger Vehicles. Both devices also enable adaptive touch technology that utilizes self-capacitance and mutual-capacitance measurements to prevent false-touch detections and to ensure that all touches are recognized, said Microchip.

The MXT2912TD-A supports nearly 3,000 touch-sensing nodes, while the MXT2113TD-A features nearly 2,000 nodes. Both implement Microchip’s proprietary maXTouch touchscreen technology, which addresses the requirements of thick lenses and supports multiple touches even with moisture present or through thick gloves.

Additionally, both devices drastically reduce emissions by implementing Microchip’s new signal-shaping technology to help touchscreen displays using maXTouch controllers comply with CSIPR-25 Level 5 standards for electromagnetic interference in automobiles.

The new controllers are also AEC-Q100–qualified and operate within automotive temperature grade 3 (–40°C to 85° C) and automotive temperature grade 2 (–40°C to 105°C) ranges.

The MXT2912TD-A and MXT2113TD-A controllers, in LQFP176 and LQFP144 packages, respectively, are available for sampling and volume quantities. An evaluation kit is available via Microchip’s purchasing portal or through its distribution network. The kit includes a printed circuit board (PCB) with the touchscreen controller, a touch sensor on a clear glass lens, a flat printed circuit (FPC) to connect to the sensor display, a converter PCB to connect the kit to the host computer via USB, and cables, software, and documentation. The parts are compatible with Microchip’s maXTouch Studio software development environment.