QT5C03-ISSG, QT60040, QT600406-2121

The QT60040 digital charge-transfer ("QT") QMatrix™ IC is designed to detect touch on up to 4 keys in a scanned 4x1 matrix. It will project the keys through almost any dielectric, like glass, plastic, stone, ceramic, and even most kinds of wood, up to thicknesses of 6mm. The touch areas are defined as simple 2-part interdigitated electrodes of conductive material, like copper, Indium-Tin-Oxide (ITO), or screened silver or carbon deposited on the rear of a control panel. Alternatively the keys can be implemented on a stick-on flex circuit that can be adhered to the rear of most panels.

The IC is designed specifically for domestic appliances, computer and peripheral control buttons, ATM machines, security panels, portable instruments, machine tools, or similar products that are subject to environmental challenges or physical attack. It permits the construction of 100% sealed, watertight keypanels that are immune to environmental factors such as humidity and condensation, temperature, dirt accumulation, or the physical deterioration of the panel surface from abrasion, chemicals, or abuse. The QT60040 contains Quantum-pioneered self-calibration, drift compensation, and digital filtering algorithms that make its sensing function extremely robust and survivable.

The device can easily control keys over graphical LCD panels or LEDs when used with clear, conductive ITO electrodes. It does not require 'chip on glass' or other exotic fabrication techniques, thus allowing the OEM to source the keymatrix from multiple vendors.

External circuitry consists only of a single, inexpensive capacitor. The sensitivity of the keys can be set by simply changing the value of this capacitor. The device has 4 outputs which indicate detection on the keys; up to 2 keys can be sensed at any one  time.

The QT60040 features automatic recalibration timeouts which will cause the device to recalibrate keys on an individual basis when they are 'stuck on' for intervals of either 10s or 60s, depending on a jumper option.

QT60040 technology makes use of an important new variant of charge-transfer sensing, transverse charge-transfer, in an XY format that minimizes the number of required scan lines and external components. Unlike older technologies it does not require one IC per key, and is cost competitive even with some rubber membrane technologies. A distinct advantage is an accelerated time to market due to the fact that custom molded membranes are not required; the entire system can be designed using common PCB materials.

The E604 board available from Quantum is a reference design that permits full evaluation of the QT60040.