A touch sensor IC has been introduced by Atmel to cater to price-sensitive consumer and mobile devices. The AT42QT1040 device is small in size (it comes in a 3 x 3mm VQFN package) and draws 31uA from a 1.8 VDC supply in low power mode.
Based on Atmel's patented QTouch charge-transfer sensing technology, acquired with Quantum Research Group last year, the AT42QT1040 is said to achieve high immunity to electrical noise thanks to spread-spectrum modulation, whilst inadvertent control inputs are avoided thanks to the inclusion of the company's Adjacent Key Suppression technology. Another reliability feature is that the AT42QT1040 automatically calibrates on power-up, remaining calibrated even when the touch surface is exposed to a build-up of moisture or other contaminants.
This ic includes four digital output channels, one of which can be configured as a proximity sensor to enable 'hidden-until-lit' functionality. Notably, each of the discrete outputs has sufficient current sinking capability to directly drive LEDs. Individual key sensitivity can be tailored to support different front panel thicknesses and materials, whilst the chip also boasts the flexibility to cope with various electrode material, sizes and shapes.
System integrators can select between two power modes: a low power mode suited to small, battery-driven devices; and a fast response mode that provides a minimum response time for applications where low touch latency is required. Aiding product development, the AT42QT1040 has a debug mode in which internal data from the chip can be accessed.