基于Atmel的AT42QT1110容性觸摸鍵驅動原理及應用方案

Atmel公司的 AT42QT1110是數字突發模式電荷傳輸(QT)型電容傳感器驅動器,可以用于任何的觸摸鍵應用. AT42QT1110所有的信號處理功能,可在各種變化的條件下提供穩定的檢測.,輸出完全是去抖動的,僅需幾個外接元件就可工作.本文介紹AT42QT1110主要特性和典型的幾種應用電路.

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.

AT42QT1110主要特性:

? Sensor Keys:

– Up to 11 QTouch? channels

? Data Acquistion:

– Measurement of keys triggered either by a signal applied to the SYNC pin or at
regular intervals timed by the AT42QT1110s internal clock

Keys measured sequentially for better performance, or in parallel groups for faster operation

– Raw data for key touches can be read as a report over the SPI interface

? Discrete Outputs:

– Configurable “Detect” outputs indicating individual key touch (7-key mode)

? Device Setup:

– Device configuration can be stored in EEPROM

? Technology:

– Patented spread-spectrum charge-transfer (direct mode)

? Key Outline Sizes:

– 6 mm x 6 mm or larger (panel thickness dependent); widely different sizes and
shapes possible, including solid or ring shapes

? Key Spacings:

– 7 mm center to center or more (panel thickness dependent)

? Layers Required:

– One

? Electrode Materials:

– Etched copper, silver, carbon, Indium Tin Oxide (ITO)

? Electrode Substrates:

– PCB, FPCB, plastic films, glass

? Panel Materials:

– Plastic, glass, composites, painted surfaces (low particle density metallic paints
possible)

? Panel Thickness:

– Up to 10 mm glass, 5 mm plastic (electrode size dependent)

? Key Sensitivity:

– Individually settable via simple commands over serial interface

? Adjacent Key Suppression? (AKS?)

– Patented AKS technology to enable accurate key detection

? Interface:

– Full-duplex SPI slave mode (1.5 MHz), “change” pin, discrete detection outputs

? Moisture Tolerance Good

? Power:

– 3V ~ 5.5V

? Package:

– 32-pin 5 x 5 mm MLF RoHS compliant

– 32-pin 7 x 7 mm TQFP RoHS compliant

? Signal Processing:

– Self-calibration, auto drift compensation, noise filtering, AKS technology

AT42QT1110應用:

– Specific package qualified for automotive applications, such as radio, keyless
entry, electric windows and sat nav


圖1.AT42QT1110帶檢測輸出和不用外接觸發器的7鍵典型應用


圖2.AT42QT1110不用外接觸發器的11鍵典型應用

圖3.AT42QT1110帶外接觸發器(SYNC模式)的10鍵典型應用