Single Key Capacitive Touch Controllers

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:
nAT42QT1010 (QT1010)
Single key with timer to reset “stuck key” condition.
nAT42QT1011 (QT1011)
Single key with no reset timer.
nAT42QT1012 (QT1012)
Single key with touch-on/touch off or “toggle” operation and power down timer
The Devices have the following Features in Common
n2.9 mm x 1.6 mm SOT-23 package
nLow power consumption (17 µA at 1.8V)
nLow cost
nEasy to implement
nRange of response speed settings
nCan 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 HeartBeat™ 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
nPower switches
nHearing aids
nIsolated buttons/sensors
nChildren’s toy
nTimers
nProximity 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 85ºC
-40 to 85ºC
-40 to 85ºC
Storage Temperature
-65 to 150ºC
-65 to 150ºC
-65 to 150ºC
Supply Current (Slow mode)
17 µA
17 µA
31.5 µA
Supply Current (Fast mode)
219 µA
(1.8V Supply Current)
219 µA
(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 [email protected]
Literature Requests
www.atmel.com/literature
Package Options
6-pin
Web Site
www.atmel.com
Visit http://www.atmel.com/singletouch for more information
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http://www.atmel.com/touch
Device selection guides, Datasheets, Application Notes, Tools, Software
Rev.: 8287A-AT42-02/10
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