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Microchip unveils automotive touchscreens with new capacitive touch controllers

Microchip has announced three new maXTouch touchscreen controllers and optimisation services which address the Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) challenges faced by developers of automotive touchscreens.

The TD family of touch controllers features a new differential mutual signal acquisition method that significantly increases the Signal-to-Noise Ratio (SNR). This allows the use of very thick glass or plastic cover lenses and multi-finger thick gloved touch support up to the equivalent of 4.5 mm polymethyl methacrylate (PMMA).

The MXT1067TD, MXT1189TD and MXT1665TD devices add several variants that are cost-optimised for nine- to 13-inch automotive touchscreens to Microchip’s portfolio and are complemented by the recently introduced MXT449TD, MXT641TD, MXT2113TD and MXT2912TD devices supporting up to 20-inch touchscreens. Each device addresses aspects of the increasing demand for functional safety features and is designed in accordance with the Automotive SPICE Level 3 capability and ISO 26262 Automotive Safety Integrity Level (ASIL) B requirements.

All devices feature a waveform shaping capability to optimise the performance of the touch controller’s radiated emissions through an EMI optimisation tool, which allows developers to enter user-defined RF limits and tune the shape of the transmitted burst waveform used for the touch-sensing acquisition.

Waveform shaping is achieved through firmware parameters derived from the tool and helps designers to position the fundamental burst frequency to work together with other in-vehicle applications, such as the remote keyless entry system. The resulting parameters are then simply added to the maXTouch configuration file, which customises the touch controller performance to the individual customer design.

This process can save the designer many hours, or even weeks, of expensive EMC test chamber time by eliminating experimentation with different configuration settings to achieve the desired EMI/EMC performance.

An evaluation kit is available for each of the parts in the new maXTouch touchscreen controller family.

Author
Neil Tyler

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