Microchip expands maXTouch touchscreen controller family

Microchip Technology Inc. has expanded its functional-safety-certified capacitive maXTouch touchscreen controller family with the addition of two new devices that target larger screen sizes in the home appliance market. The newest additions to the family of IEC/UL 60730 Class B certified touchscreen controllers are the MXT448UD-HA and MXT640UD-HA that extend the Class B portfolio beyond 10 inches.

The new touchscreen controllers target networked and connected home appliances. In addition to Class B, the new devices are compliant with the IEC61000-4-6 Class A specification for conducted noise immunity up to 10 Vrms (level three for industrial use). This enables products with a touch-screen interface to function in harsh factory environments where electromagnetic interference  (EMI) can be caused by conveyer belts, power rails or assembly machinery, said Microchip. For home appliances, this can eliminate false or missed touches caused by EMI from unshielded power transmission, electric motors, and neighboring electrical equipment.

Click for a larger image. (Source: Microchip Technology)

These touchscreen controllers feature two serial interfaces (SPI and I²C) that operate simultaneously, offering redundancy in a design through the integration of safety features, such as individual communication between the touchscreen controller to the host microprocessor (MPU) in addition to a safety microcontroller (MCU), said Microchip. Touch events are provided to both processors at the same time.

“This unique architecture shortens time to market and reduces development cost by allowing all safety-critical firmware to be developed on a dedicated safety-certified MCU (with mandatory source code review by an IEC/UL test lab) separate from the main processor running the appliance’s graphical user interface (GUI),” said the company.

The MXT448UD-HA and MXT640UD-HA touchscreen controller family operates up to to 105°C, which makes them suited for cooktops and ovens where the human machine interface (HMI) system is near heating elements. The operating temperature range is -40°C to 105°C.

The ATMXT448UD-CCUHA1 and ATMXT640UD-CCUHA1 for home appliances are available in volume production starting at $2.40 for the ATMXT448UD part in quantities of 10,000. A general-purpose ATEVK-MXT640UD-A Evaluation Kit (EVK) also is available. Designers can request a home appliance functional safety version of the kit. Development tools include the maXTouch Studio and maXTouch Analyzer for production end-of-line test and inspection.

Earlier this year, Microchip introduced the maXTouch MXT2912TD-UW touchscreen controller for automotive applications, targeting ultra-wide display sizes up to 45 inches with a very wide aspect ratio.