AT42QT1110-MU View Datasheet(PDF) - Atmel Corporation
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AT42QT1110-MU Datasheet PDF : 50 Pages
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2. Overview of the AT42QT1110
2.1 Introduction
The AT42QT1110 (QT1110) is a digital burst mode charge-transfer (QT™) capacitive sensor driver designed for any
touch-key applications.
The keys can be constructed in different shapes and sizes. Refer to the Touch Sensors Design Guide and
Application Note QTAN0002, Secrets of a Successful QTouch Design, for more information on construction and
design methods (both downloadable from the Atmel website).
The device includes all signal processing functions necessary to provide stable sensing under a wide variety of
changing conditions, and the outputs are fully debounced. Only a few external parts are required for operation.
The QT1110 modulates its bursts in a spread-spectrum fashion in order to suppress heavily the effects of external
noise, and to suppress RF emissions.
2.2 Configurations
The QT1110 is designed as a versatile device, capable of various configurations. There are two basic configurations
for the QT1110:
11-key QTouch. The device can sense up to 11 keys.
7-key QTouch with individual outputs for each key. The device can sense up to 7 keys and drive the matching
Detect outputs to a user-configurable PWM.
Both configurations allow for a choice of acquisition modes, thus providing a variety of possibilities that will satisfy
most applications (see the following sections for more information).
Additionally, the SYNC line can be used as an external trigger input. Note that in 11-key mode the SYNC line
replaces one key, thus allowing only 10 keys.
See Section 4.7 on page 18 for more information.
2.3 Guard Channel
The device has a guard channel option (available in all key modes), which allows one key to be configured as a
guard channel to help prevent false detection. See Section 4.9 on page 19 for more information.
2.4 Self-test Functions
The QT1110 has two types of self-test functions:
Internal Hardware tests – check for hardware failures in the device internal memory.
Functional checks – confirm that the device is operating within expected parameters.
See Section 4.10 on page 20 for more information.
2.5 Moisture Tolerance
The presence of water (condensation, sweat, spilt water, and so on) on a sensor can alter the signal values
measured and thereby affect the performance of any capacitive device. The moisture tolerance of QTouch devices
can be improved by designing the hardware and fine-tuning the firmware following the recommendations in the
application note Atmel AVR3002: Moisture Tolerant QTouch Design (www.atmel.com/Images/doc42017.pdf).
AT42QT1110-MU / AT42QT1110-AU [DATASHEET]
7
9520J–AT42–05/2013
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