Safety certified capacitive touchscreen controller family for the home appliance market

Reducing the risk of fires in the kitchen and also floods in the laundry room, European IEC 60730 and U.S. UL 60730 Class B specifications demand safety mechanisms in home appliances, including ovens, cooktops, washing machines and clothes dryers. Enabling designers to satisfy these functional safety needs in touch screen enabled appliances, Microchip Technology has released its maXTouch MXT336UD-MAUHA1 capacitive touchscreen controller family — claimed to be the market’s only touchscreen controllers to provide pre-certified, Class B firmware. The family comprises three controllers, the MXT112UD-MAUHA1, the MXT228UD-MAUHA1 and the MXT336UD-MAUHA1, each providing different screen size requirements, ranging from 2" to 8".

The Class B certified touch controllers provide exceptional safety-related features that allow system shut off via an intuitive soft button on a touchscreen, removing the need for an external safety certified stop or cancel button and associated MCU. They also enable an appliance to detect a touchscreen or appliance failure and shut down automatically via a variety of self-testing capabilities. For example, if the glass breaks on a cooktop, the touchscreen will turn dark and shut off the machine, removing accidental damage in the home. As the number of touch-enabled home appliances continue to increase, the device family moves the needed safety functionality to a simplified single touchscreen interface, allowing OEMs to reduce costs and improve time to market.

“Due to the risk of house fires caused by home appliances, appliance manufacturers must add functional safety to their machines, and Microchip’s MXT336UD-MAUHA1 touchscreen controller family is already certified for these required safety standards,” said Fanie Duvenhage, vice president of Microchip’s human-machine interface business unit. “Integrating Class B certification into our touch controllers eases the design and qualification process for touch-enabled appliances, ultimately putting safety first, while reducing costs and enabling modern user interface solutions.”

Also, this new family provides a high SNR design and proprietary differential mutual acquisition scheme. This enables the machine to reliably detect and track multiple fingers on surfaces exposed to moisture, water, grease and more — even if the user is wearing gloves.