Datasheet

3
9502A–AT42–07/08
AT42QT2160
3. Introduction
The QT2160 device is a digital burst mode charge-transfer (QT) sensor designed specifically for
matrix layout touch controls; it 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 QT2160 employs transverse charge-transfer (QT) sensing, a technology that senses
changes in electrical charge forced across two electrode elements by a pulse edge (see
Figure 3-1). The QT2160 allows a wide range of key sizes and shapes to be mixed together in a
single touch panel.
The device uses an
I
2
C-compatible interface to allow key data to be extracted and to permit
individual key 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.
14 X4 O X matrix drive line / shared GPO X4 Leave open
15 X5 O X matrix drive line / shared GPO X5 Leave open
16 Vdd P Power -
17 Vdd P Power -
18 Vss P Supply ground -
19 Y0B I/O Y line connection Leave open
20 Y1B I/O Y line connection Leave open
21 I2CA0 I I
2
C-compatible address select -
22 I2CA1 I I
2
C-compatible address select -
23 SDA OD Serial Interface Data -
24 SCL OD Serial Interface Clock -
25 RST
I
Reset low; has internal 30k - 60k pull-
up
Leave open or
Vdd
26 Y0A I/O Y line connection Leave open
27 Y1A I/O Y line connection Leave open
28 GPIO1 I/O General purpose input/output 1
Table 2-1.Pin Listing (continued)
Pin Function I/O Comments
If Unused,
Connect To...