Single Key Capacitive Touch Controllers The AT42QT101x single key capacitive touch controller family provide touch key replacements for mechanical buttons. The ICs are low cost, and as such can be added to designs with minimal impact on the bill of materials. Each Device has Different Operation: n n n AT42QT1010 (QT1010) Single key with timer to reset "stuck key" condition. AT42QT1011 (QT1011) Single key with no reset timer. AT42QT1012 (QT1012) Single key with touch-on/touch off or "toggle" operation and power down timer The Devices have the following Features in Common n n n n n n 2.9 mm x 1.6 mm SOT-23 package Low power consumption (17 A at 1.8V) Low cost Easy to implement Range of response speed settings Can be configured for use as a proximity sensor 2 AT42QT1010 and AT42QT1011 The AT42QT1010 and AT42QT1011 are identical apart from their behavior when the sensor is "in detect" for an extended period. The AT42QT1010 has a "maximum on" duration of ~ 60s. If there is an obstruction on the sensor, the device output will go low after the "maximum on" detection period, so that subsequent touches can be detected. The AT42QT1011 has no timer and the device will remain on whilst the sensor is activate. Speed Settings The AT42QT1010 and AT42QT1011 have three speed settings: n For devices where a quick response is required, a fast response setting is available with a 12.2 ms maximum response time. n It is also possible to set up the device for low power consumption, at the expense of a slower response time of up to 88.6 ms. n A third option is to synchronize the device to an external clock which makes it possible to synchronize several ICs in the same device. This technique can be used to enhance noise immunity by syncing to a noise source such as mains. The response time is then dependent on the external clock. When the device is in low power mode or when the synchronisation mode is selected, a HeartBeatTM output is available. This provides a pulse whilst the device isn't in detect which can be used to verify the device is working correctly. AT42QT1012 The device is similar to the AT42QT1010 and AT42QT1011 but it has touch-on/touch-off (toggle) functionality and a power down timer. Auto Off Timers The QT1012 has a number of options for automatic power down which can be used to conserve power in situations where the device could be left on inadvertently. There are predefined power down settings which can be used to power the device down after 15 minutes or 60 minutes. There is also the option for no power down timer so the device remains on until touched again. Single-Key Touch Controllers AT42QT1010 AT42QT1011 AT42QT1012 Single button or proximity sensor Single button or proximity sensor Single button or proximity sensor Prolonged touch timeout after 60 seconds No power down, remains active while touch present Toggle (touch on/off) functionality Power down after configurable time period www.atmel.com/singletouch Standard Features The following functionality is common to all three ICs in the AT42QT101X family. Drift Compensation Drift compensation algorithms constantly adjust the reference level in the device to ensure that the key will remain calibrated even if there is a large change in background capacitance. Spread Spectrum Acquisition The devices modulate their frequency whilst measurements are taken. This has the effect of reducing emission levels and susceptibility to interference as there is no single burst frequency. Power Consumption All the devices have a range of power modes depending on the response time required. The power consumption is kept to a minimum whatever power mode the device is in. This, combined with the auto-off functionality available on the QT1012 means that for portable devices, adding capacitive sensing functionality does not significantly impact on the battery lifetime. Sensitivity By careful capacitor selection and key design, the sensitivity of a capacitive button can be set to work with a wide range of panel thicknesses and materials. As the sensitivity of the key can be varied significantly it is also possible to use any of the single key devices as proximity sensors. Such functionality can be used in toys or used to illuminate "hid den until lit" user interfaces. Calibration The device will automatically calibrate on power up. If there is an obstruction on the key for a prolonged period, the sensor will re-calibrate after a set time period (with the exception of the QT1011, which will indicate a touch condition as long as the sensor is "in detect"). This ensures that the device will detect a new touch correctly. Detection In order for the sensors to only go active on intended touches, the ICs include signal processing which helps to suppress detections caused by electrical noise and quick brushes with the surface. Typical Applications n Power switches n Hearing aids n Isolated buttons/sensors n Children's toy n Timers n Proximity sensors 3 Headquarters Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: (1) 408 441-0311 Fax: (1) 408 487-2600 Specifications System International Number of Keys 1 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 Number of I/O lines 1 output channel Key outline sizes 6 mm x 6 mm recommended or arbitrary shape Signal processing Noise filtering, self calibration on startup, automatic drift compensation 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 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 Recommended Operating Conditions AT42QT1010 AT42QT1011 AT42QT1012 Power Supply 1.8V-5.5V 1.8V-5.5V 1.8V-5.5V Power Supply Ripple + Noise 20 mV 20 mV 20mV Operating Temperature -40 to 85C -40 to 85C -40 to 85C Storage Temperature -65 to 150C -65 to 150C -65 to 150C Supply Current (Slow mode) 17 A 17 A 31.5 A Supply Current (Fast mode) 219 A (1.8V Supply Current) 219 A (1.8V Supply Current) N/A 2.9 mm x 1.6 mm SOT-23 2.9 mm x 1.6 mm SOT-23 2.9 mm x 1.6 mm SOT-23 Environmental Specifications DC Specifications Product Contact Product Line email touch@atmel.com Literature Requests www.atmel.com/literature Package Options 6-pin Web Site www.atmel.com Visit http://www.atmel.com/singletouch for more information (c) 2010 Atmel Corporation. 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