QT411 Datasheet, PDF (1/12 Pages) Quantum Research Group – QSLIDE TOUCH SLIDER IC

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QT411-ISSG
QSLIDE™ TOUCH SLIDER IC
z QT401 QSlide™ enhancement - simplified calibration
z Linear finger-touch capacitive slider control
z Robust Charge-Transfer sensing method
z Extremely simple circuit - no external active components
z SPI slave-mode interface
z Self-calibration and drift compensation
z Spread-spectrum operation for optimal EMC compliance
z 2.5 - 5.5V single supply operation; very low power
z Enhanced power supply & thermal drift rejection
z 14-pin TSSOP Pb-free package
z Compatible with clear ITO over LCD construction
z Inexpensive, simple 1-sided PCB construction possible
VDD
SDO
/SS
SCLK
SNS3B
SNS3A
SNS2B
1
14
2
13
3 QT411 12
4
11
5
10
6
9
7
8
GND
DRDY
DETECT
SDI
SNS1A
SNS1B
SNS2A
APPLICATIONS
y Personal electronics
y Appliance controls
y Climate controls
y Automotive controls
The QT411 QSlide™ IC is a new type of linear capacitive touch ‘slider’ sensor IC based on Quantum’s patented
charge-transfer (‘QT’) methods. This unique IC allows designers to create speed or volume controls, menu bars, and other
more exotic forms of human interface on the panel of an appliance or personal electronic device. Generally it can be used to
replace any form of linear control, through a completely sealed panel.
The device uses a simple, inexpensive resistive sensing element between four connection points. The sense element can be a
straight line or curved. The device can report a single rapid touch anywhere along the sense element, or, it can track a finger
moving along the sensing surface in real time.
This device uses three channels of synchronous sensing across a resistive element to determine touch position, using
mathematical analysis. A positional accuracy of 5% (or better) is relatively easy to achieve. The acquisitions are performed in a
burst mode which uses proprietary spread-spectrum modulation for superior noise immunity and ultra-low RF low emissions.
The output of the QT411 can also be used to create discrete controls buttons in a line, by interpreting sets of number ranges
as buttons. For example, the number range 0..19 can be button A, 30..49 button B, 60..79 button C etc. Continuous slider
action and number-range based discrete control points can be mixed on a single element, or, the element can be reinterpreted
differently at different times, for example when used adjacent to or on top of an LCD to act as a menu input device that
dynamically changes function in context. The device is compatible with ITO (Indium Tin Oxide) overlays on top of various
displays or simply to provide for a backlighting effect.
The QT411 is significantly more stable with temperature and other environmental influences than the QT401 which it is
designed to replace. In particular it can tolerate extreme temperature swings without false detection or shifts in reported touch
position. Also it does not require special calibration of the endpoints of the slider area. However, unlike the QT401 the QT411
does not have a proximity detection function.
LQ
Copyright © 2005 QRG Ltd
QT411-ISSG R6.01/1005