OVERVIEW
The QT60040 is a CMOS charge-transfer (QT) sensor designed specifically for matrix touch controls; it includes all signal processing functions necessary to provide stable sensing under a wide variety of changing conditions. Only one low cost external capacitor is required for operation.
The QT60040 uses burst-mode charge transfer methods pioneered and patented by Quantum. This revolutionary new technology allows the construction of entirely new forms of keypanels which can include back-illumination, arbitrary shapes of keys, morphed keys wrapped onto complex surfaces, and keys having unique textures and feel, all at very low cost.
The QT60040 uses a 4x1 matrix, having 4 X drive lines and 1 Y receive line. This configuration reduces interconnect requirements and also lowers the external component count to one charge sampling capacitor which is sequentially shared by the four keys.
The QT60040 has four simple active-high CMOS outputs that go high when the corresponding key is touched. Up to 2 keys can be touched at the same time; three or more keys touched will limit to the first two touch outputs. An option pin allows this to be restricted to only one key if desired.
The device operates on a 2.5 to 5.5 regulated power supply which can be from a common 78L05-type IC regulator or a simple 2-stage zener regulator supply.

● Creates 4 ‘touch buttons’ through any dielectric
● Only 1 inexpensive capacitor required
● Simple 4x1 matrix key geometry
● 100% drift compensation for lifetime reliability
● 2 key rollover: senses any 2 keys at same time
● Back-lit keys possible with ITO electrodes
● Simple direct per key active-high drive outputs
● Auto recalibration after 10 or 60 seconds of touch
● 2.5 - 5.5V single power supply operation
● CMOS design - very low power consumption
● 14-pin SOIC package
● E604 Evaluation reference design board available

APPLICATIONS -
♦ Security keypanels
♦ Appliance controls
♦ ATM machines
♦ Automotive controls
♦ Industrial keyboards
♦ Vandal-proof keypads
♦ Touch-screens
♦ PC / peripheral controls