LQ
4-K
EY
C
HARGE
-T
RANSFER
IC
VDD
X1
OPT1
OPT2
Q1
Q2
Q3
1
2
3
4
5
6
7
14
13
12
11
10
9
8
GND
X2
X3
X4
Y
CS
Q4
QT60040
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
Industrial keyboards
Appliance controls
Vandal-proof keypads
ATM machines
Touch-screens
Automotive controls
PC / peripheral controls
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
AVAILABLE OPTIONS
T
A
SOIC
0
0
0 C to +70 C
-
0
0
-40 C to +85 C
QT60040-IS
DIP
QT60040-D
-
Copyright © 2000 Quantum Research Group Ltd
lQ
QT60040 / R1.04 / 0303
QUANTUM [ QUANTUM RESEARCH GROUP ]
