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Touch controller integrates guard channel facility

Since acquiring Quantum Research Group earlier this year, Atmel has significantly expanded it range of user interface technology incorporating Quantum's capacitive sensing capabilities. The latest addition is a touch control chip, the AT42QT1060, which integrates six touch sensing channels and can drive up to seven low current LED drivers ” it provides all the signal processing and input/output functions needed to create a touch interface for a mobile phone or other handheld device.

Notably, this part addresses the issue of false detections ” a notorious challenge when integrating touch sensor capability into a handheld device. The AT42QT1060 combines Quantum's patented Adjacent Key Suppression technology, which ensures that only the intended key is activated by the touch of a finger, with the ability to adjust individual key sensitivity to provide a guard channel feature. For example, to implement joystick functionality in a phone, four of the AT42QT1060's sensor channels could be connected to four discrete touch keys in a quadrant arrangement, with the fifth for a touch pad in the centre. The sixth channel could be used to provide guard band capability to prevent false detections on the other keys when the device is in a pocket or held to the user's ear.

The device is available in a 28pin, 4 mm x 4 mm RoHS compliant package. Operating from 5.5V dc down to 1.8V dc, it is said to consume less than 1uA in standby mode. Among its power saving features is a host wake up function that allows the host to sleep and be woken up when the user triggers the corresponding input.

The AT42QT1060 functions through any insulating panel including glass or plastic up to 3mm thick. Electrodes can be made from copper, silver, carbon, indium tin oxide (ITO) or Orgacon conductive ink and must be 6 x 6mm or larger. Different electrode sizes and shapes are possible, giving the product designer great flexibility in tailoring the user interface.

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