Overview – Rainbow Electronics AT42QT4160 User Manual
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9507AS–AT42–10/08
AT42QT4160
2.
Overview
The AT42QT4160 (QT4160) QField IC is a self-contained capacitive touchscreen controller that
employs Atmel’s patented transverse charge-transfer (QT
™
) acquisition method. The controller
senses changes in electrical charge forced across two electrode elements by a pulse edge (see
).
Figure 2-1.
Field Flow Between X and Y Elements
The touchscreen is critical to the design and is specially patterned to improve linearity, limit hand
shadow and keep the number of connection lines to a minimum.
The device 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. The
entire circuit can be built within a few square centimeters of single-sided PCB area. CEM-1 and
FR1 punched, single-sided materials can be used for the lowest possible cost. The PCB’s rear
can be mounted flush on the back of a glass or plastic panel using a conventional adhesive,
such as 3M VHB two-sided adhesive acrylic film.
The device uses an I
2
C-compatible interface to allow channel data to be extracted and to permit
touchscreen parameter setup. The command structure is designed to minimize the amount of
data traffic while maximizing the amount of information conveyed.
In addition to normal operating and setup functions the device can also report back actual signal
strengths.
overlying panel
X
eleme nt
Y
elem ent