ATMEL TOUCH TECHNOLOGY AT42QT1040 Low-cost Touch Sensor Controller for Mobile Devices The AT42QT1040 (QT1040) IC is a convenient and easy-to-use touch sensor controller for up to four capacitive touch keys. The device comes in an ultra-small 20-pin 3 mm x 3 mm VQFN package, making it ideal for use in space-constrained mobile devices. This new low-cost IC makes it possible to replace mechanical buttons in mobile and consumer devices with Atmel’s QTouch™ technology. n4-channel touch sensor IC n4 outputs for per-channel touch indication nLow operating voltage 1.8 to 5.5 V nUltra-low power consumption (31 mA, 64 ms between acquisitions, 1.8 V) nOption to configure output as proximity sensor n2 response speed settings nDebug output provided to aid design nRoHS-compliant package Key Sensitivity Reliability The channels on the QT1040 are individually configurable for sensitivity to support a wide range of front panel materials and thicknesses. It is possible to configure any one of the channels as a proximity sensor that can be used to illuminate “hidden until lit” keys on an approaching hand. As with all Atmel devices, the QT1040 is extremely reliable, thanks to Atmel’s patented technology. Response Speed The response speed can be configured either for low latency (16 ms), or for a slightly slower response (64 ms) with the benefit of reduced power consumption. The setting used depends on product requirements. Tightly spaced key pads can prove a challenge when using capacitive touch buttons: nearby fingers can cause false detections, or a hovering hand can activate channels. Atmel’s patented Adjacent Key Suppression™ (AKS™) technology overcomes these issues. AKS isolates the key with the largest signal, and then suppresses signals from all other keys whilst the selected key is pressed, so false key detections do not occur. TM Self-calibration Debugging Output The device automatically self-calibrates within 0.1 seconds of applying power. If a touch key is miscalibrated at power-on (for example, if a finger is held over the key), the device automatically recalibrates as the finger is removed. Similarly, a recalibration takes place if a channel is triggered for longer than a specified time-out period. The QT1040’s debugging mode can be used to watch selected variables in the device. Data is clocked at a rate of 200 kHz, which means that channels can be monitored with great accuracy. The ability to log the behavior of the device in this way means quicker isolation and resolution of issues, and a shorter design life cycle. Auto Drift Compensation Drift compensation algorithms constantly adjust the reference level in the device to ensure that the keys remain calibrated even if there is a large change in background capacitance. Headquarters Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: +1 408 441-0311 Fax: +1 408 487-2600 International Atmel Asia Unit 01-05 & 16, 19/F BEA Tower, Millennium City 5 418 Kwun Tong Road Kwun Tong Kowloon Hong Kong Tel: +852 2245-6100 Fax: +852 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 St Quentin-enYvelines Cedex France Tel: +33 1-30-60-70-00 Fax: +33 1-30-60-71-11 System Number of keys Up to 4 Number of I/O lines 4 output channels Key outline sizes Typically 8–10 mm advised, although they can be smaller; and of varied shapes Key spacings 7 mm center to center typical; depends on panel thickness Signal processing Adjacent Key Suppression, noise filtering, self-calibration on start-up, automatic drift compensation Electrical and Environmental Specifications Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: +81 3-3523-3551 Fax: +81 3-3523-7581 Touch Technology Division 1 Mitchell Point Ensign Way Hamble Southampton Hampshire SO31 4RF United Kingdom Tel: +44 23-8056-5600 Fax: +44 23-8045-3939 Product Contact Recommended Operating Conditions Power supply 1.8V to 5.5V Power supply ripple + noise ±5 mV Product Line [email protected] Literature Requests www.atmel.com/literature Environmental Specifications Operating temperature -40ºC to +85ºC Storage temperature -55ºC to + 125ºC Web Site www.atmel.com DC Specifications Supply current, slow mode, 64 ms between acquisitions 31 µA @ 1.8V Supply current, fast mode, 16 ms between acquisitions 104 µA @ 1.8V Package Options 20-pin 3 mm x 3 mm x 0.85 mm VQFN RoHS compliant More Information? © 2009 Atmel Corporation. All rights reserved. Atmel®, Atmel logo and combinations thereof, Adjacent Key Suppression™, AKS™, QTouch™ and others are registered trademarks or trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be trademarks of others. Rev.: 10616A-AT42-03/09/0M The QT1040 datasheet is available from our website – www.atmel.com/products/touch There is also an evaluation kit available (EVK1040A) that allows you to experiment with different configurations and settings. It is supplied ready to use, with documentation. Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. 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