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" Eight completely independent QT touch sensing fields " Designed for low-power portable applications " 100% autocal for life - no adjustments required " Direct outputs - either encoded or ‘per key’ " Fully debounced results " 2.8V to 5.0V single supply operation " 45µA current typ @ 3V in 360ms LP mode " AKS™ Adjacent Key Suppression " Spread spectrum bursts for superior noise rejection
OSC VDD SNS0K /RST SNS0 OUT_0 OUT_1 OUT_2 OUT_3 OUT_4 OUT_5 OUT_6 OUT_7 25 26 27 28 29 30 31 32
QT1080
8 KEY QTOUCH™ SENSOR IC
SYNC/LP DETECT SNS7K SNS6K SNS5K SNS7 SNS6 VSS
24 23 22 21 20 19 18 17 SNS5 SNS4K SNS4 SNS3K SNS3 SNS2K SNS2 SN1K
16 15 14
QT1080 32-QFN
13 12 11 10 9
" 10ms ‘Fast mode’ for use in slider applications " RoHS compliant packages: 32-QFN and 48-SSOP
APPLICATIONS
! ! MP3 players Mobile phones ! ! PC peripherals Television controls ! ! Pointing devices Remote controls
QT1080 charge-transfer (’QT’) QTouch IC is a self-contained digital controller capable of detecting near-proximity or touch on up to eight electrodes. It allows electrodes to project independent sense fields through any dielectric such as glass or plastic. This capability coupled with its continuous self-calibration feature can lead to entirely new product concepts, adding high value to product designs. The devices are designed specifically for human interfaces, like control panels, appliances, gaming devices, lighting controls, or anywhere a mechanical switch or button may be found; they may also be used for some material sensing and control applications. Each of the channels operates independently of the others, and each can be tuned for a unique sensitivity level by simply changing a corresponding external Cs capacitor. AKS™ Adjacent Key Suppression (patent pending) suppresses touch from weaker responding keys and only allows a dominant key to detect; for example to solve the problem of large fingers on tightly spaced keys. Spread-spectrum burst technology provides superior noise rejection. These devices also have a SYNC/LP pin which allows for synchronization with additional similar parts and/or to an external source to suppress interference, or, a Low Power (LP) mode which conserves power. By using the charge-transfer principle, this device delivers a level of performance clearly superior to older technologies yet is highly cost-effective. This part is available in both 32-QFN and 48-SSOP RoHS compliant packages.
TA
-40ºC to +85ºC
AVAILABLE OPTIONS 32-QFN
QT1080-ISG
48-SSOP
QT1080-IS48G
LQ
Copyright © 2004-2006 QRG Ltd QT1080 R11.06/0806
SNS1
N.C.
SS
" Sync pin for excellent LF noise rejection
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Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Device Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 Start-up Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Option Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 OUT Pins - Direct Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4 OUT Pins - Binary Coded Mode . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.5 DETECT Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.6 SYNC/LP Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.7 AKS Function Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.8 MOD_0, MOD_1 Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.9 Fast Detect Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.10 Simplified Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.11 Unused Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Design Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.1 Oscillator Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Spread-spectrum Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Cs Sample Capacitors - Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 PCB Layout and Construction . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Absolute Maximum Specifications . . . . . . . . . . . . . . . . . . . . . . . 4.2 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . 4.3 AC Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..