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Automotive touchscreen controllers support reduced EMI

July 09, 2019

cmathas-July 09, 2019

Designers of wide and extremely wide touchscreens increasingly used in automotive display applications have faced electromagnetic interference (EMI) and electromagnetic compatibility (EMC) challenges. Microchip has introduced three maXTouch touchscreen controllers to its TD family that provide a new differential mutual signal acquisition method to significantly increase signal-to-noise ratio (SNR). This allows designers to use very thick glass or plastic cover lenses and multi-finger thick-gloved touch support up to the equivalence of 4.5 mm polymethyl methacrylate (PMMA).

The new MXT1067TD, MXT1189TD, and MXT1665TD are cost-optimized for 9- to 13-inch automotive touchscreens. Each device is designed in accordance with the Automotive SPICE Level 3 capability and ISO 26262 Automotive Safety Integrity Level (ASIL) B requirements.

The TD family relies on a unique waveform-shaping capability to optimize the performance of the touch controller’s radiated emissions through an EMI optimization tool. The tool allows developers to enter user-defined RF limits and tune the shape of the transmitted burst waveform. Waveform shaping helps designers to position the fundamental burst frequency to work together effectively with other in-vehicle applications. The results are added to the maXTouch configuration file, which customizes touch-controller performance to the design, saving, in some cases, weeks of expensive EMC test chamber time to achieve the desired EMI/EMC performance, according to Microchip.

The TD family, including the three new members, enables the use of the same design environment and product features for a variety of sizes, use cases, different cover lens materials, and thicknesses across vehicle models. Eight dedicated application and sensor design centers globally assist customers with configurations based on screen size and aspect ratio to the type and provider of the display and the architecture of the complete stackup. maXTouch EMI optimization is part of the support provided by the design centers.

An evaluation kit is available for each of the maXTouch touchscreen controller devices. Kit numbers are ATEVK-MXT1067TDAT-A (I2C), ATEVK-MXT1189TDAT-A (I2C), ATEVK-MXT1189TDAT-C (SPI), ATEVK-MXT1665TDAT-A (I2C), and ATEVK-MXT1665TDAT-C (SPI). Each kit includes a PCB with the maXTouch touchscreen controller, a touch sensor on a clear glass lens, the flat printed circuit (FPC) to connect to the sensor, a bridge PCB to connect the kit to the host computer via USB, cables, software, and documentation.

The MXT1067TD, MXT1189TD, and MXT1665TD devices are sampling, and volume quantities are available in TQFP128 (for the MXT1067TD only) and LQFP144 packages. Evaluation kits are available for purchase at the Microchip purchasing portal .

>> This article was originally published on our sister site, Electronic Products: "Microchip launches three maXTouch touchscreen controllers."

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