at42qt1085 ATMEL Corporation, at42qt1085 Datasheet - Page 5

• Manufacturer Part Number: at42qt1085
• Description: Qtouch 8-key Touch Sensor Ic
• Manufacturer: ATMEL Corporation

2. Overview
2.1
9625BSX–AT42–05/11
Introduction
The AT42QT1085 (QT1085) is an easy to use dual-pulse mode sensor IC based on Atmel
principles for robust operation and ease of design. It is intended for any touch-key application.
The QT1085 is capable of detecting near-proximity or touch on up to eight sensor channels,
configured as keys, and 12 dedicated GPIO channels. Four additional GPIO channels can be
configured by replacing four of the sensor channels (one per channel).
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
more information on construction and design methods (both downloadable from the Atmel
website).
Each GPIO channel may be configured as a digital input or output. In output mode, a GPIO pin
may be set to output a PWM signal at any of 16 duty cycles (4-bit PWM). The QT1085 allows
electrodes to project sense fields through any dielectric such as glass or plastic.
This device has many advanced features which provide for reliable, trouble-free operation
over the life of the product. In particular the QT1085 features advanced self-calibration, drift
compensation, and fast thermal tracking. The QT1085 can tolerate some fluctuations in the
power supply, and in many applications will not require a dedicated voltage regulator.
A full haptics engine is integrated into the device, allowing feedback effects to be triggered on
key detection or directly activated by a host microcontroller.
The QT1085 includes all signal processing functions necessary to provide stable sensing
under a wide variety of changing conditions. Only a few external parts are required for
operation and no external Cs capacitors are required.
The QT1085 modulates its acquisition pulses in a spread-spectrum fashion in order to heavily
suppress the effects of external noise, and to suppress RF emissions. The QT1085 uses a
dual-pulse method of acquisition. This provides greater noise immunity and eliminates the
need for external sampling capacitors, allowing touch sensing using a single pin.
AT42QT1085
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Design, for
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