Microchip Introduces Family of Capacitive Touch Screen Controllers for Home Appliance Market

     Connected home appliances allow both users and manufacturers to communicate with them over the Internet. For example, users of kitchen ovens can find new recipes online, and manufacturers can implement remote diagnostics or over-the-air firmware updates. Displays and touch sensors are critical to enabling this functionality in modern appliances. Microchip Technology Inc. announced that two new members, the MXT448UD-HA and MXT640UD-HA, have been added to its line of IEC/UL 60730 Class B certified touchscreen controllers. The new product expands the scope of application of the B-class product portfolio to more than 10 inches, and is a dedicated solution for larger screen sizes, while customers can also adjust according to their needs.

     In addition to meeting the Class B specification, the new device also meets the IEC61000-4-6 Class A specification, with conducted noise immunity up to 10 Vrms (Class 3 for industrial use). This enables products with touchscreen interfaces to operate in very harsh factory environments where conveyor belts, power lines or assembly machinery can cause electromagnetic interference. Appliance manufacturers will benefit from increased reliability and productivity. This is a significant improvement over consumers using unprotected touchscreens on ovens or washing machines, where unprotected power transmission, electrical motors, and electromagnetic interference from adjacent electrical equipment can lead to false or missed touches.

     The new touchscreen controller also features two serial interfaces (SPI and I²C) that can operate simultaneously, by integrating safety functions such as separate communication between the touchscreen controller and the host microprocessor (MPU) and the safety microcontroller (MCU) , allowing redundancy in the design. Touch events are provided to both processors at the same time. This unique structure reduces time-to-market and development costs as it allows all safety-critical firmware to be developed on a dedicated, safety-certified MCU (mandatory source code review by IEC/UL test labs), Separate from the main processor that runs the device's graphical user interface (GUI).

     "As products add more control through touchscreens, interfaces must work reliably to meet user needs and protect users," said Clayton Pillion, director of Microchip's Human Interface Business Unit. "maXTouch® technology has excellent noise immunity and can be used throughout its life. Safe and robust operation over time. Working closely with our customers, we launched the first series of functionally safe touch controllers with high adoption rates in scenarios where noise immunity is critical to product success.”

     In addition to complying with IEC standards, the MXT448UD-HA and MXT640UD-HA series also support operating temperatures up to 105°C. This is a key requirement for cooktops and ovens where human-machine interface (HMI) systems are close to heating elements.