QT240-IG QUANTUM [Quantum Research Group], QT240-IG Datasheet
QT240-IG
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QT240-IG Summary of contents
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... PC Peripherals Backlighted buttons The QT240 charge-transfer (“QT’”) QTouch self-contained digital sensor IC capable of detecting near-proximity or touch on 4 electrodes. It allows electrodes to project independent sense fields through any dielectric like glass, plastic, stone, ceramic, and wood. It can also turn metal-bearing objects into intrinsic sensors, making them responsive to proximity or touch. ...
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... OVERVIEW QT240 devices are burst mode digital charge-transfer (QT) sensor ICs designed specifically for touch controls; they include all hardware and signal processing functions necessary to provide stable sensing under a wide variety of conditions. Only a single low cost capacitor per channel is required for operation. ...
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... C1 22nF added to overly sensitive channels to ground, to reduce their gains. These should be on the order of a few picofarads QT240 SPECIFICS 2.1 SIGNAL PROCESSING These devices process all signals using 16 bit math , using a number of algorithms pioneered by Quantum. These algorithms are specifically designed to provide for high survivability in the face of adverse environmental changes ...
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... Cx should be below 50pF to prevent errors; this value can be read with a conventional capacitance meter with the QT240 removed. The option setting resistors are mandatory and cannot be deleted. The must be strapped to either Vdd or Vss. ...
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... A sync pulse on SYNC/SS in slow mode acts to break the QT240 out of its sleep state between bursts, and to do infinite another burst. The device will then go back to sleep again and await a new SYNC pulse Sync pulse does not arrive within about 90ms, it will wake again and run normally ...
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... The QT240 will track slow changes in Vdd, but can be seriously affected by rapid voltage steps. If the supply is shared with another electronic system, care should be taken to assure that the supply is free of digital spikes, sags, and surges which can cause adverse effects. The supply is best locally regulated using almost any 3-terminal LDO device from 4.0V to 5V. For proper operation a 0.1µ ...
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... Higher values of Rsns will make crosstalk problems worse; try to keep Rsns to 22K or less if possible. In general try to keep the QT240 close to the electrodes and reduce the adjacency of the sense wiring to ground planes lQ and other signal traces; this will reduce the Cx load, reduce interference effects, and increase signal gain ...
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... Fosc; fast mode only; Circuit of Figure 1-2 bursts Fast mode only Units Notes mA Fast mode µA Slow mode, no Sync V/s Req’d for startup, w/o reset circuit V /RES V /RES V SYNC V SYNC V OUTn, 4mA sink V OUTn, 1mA source µA OPT1, OPT2, OPT3 bits QT240R R1.10/0905 O C ...
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... Nominal timing dependent on Fosc, Sync ms/level Nominal timing dependent on Fosc, Sync secs Nominal timing dependent on Fosc, Sync secs Option pin selected; Nominal timings; dependent on Fosc, Sync B A ø G Base level Metric (mm) Min Typ 7.39 4.98 0.23 6.88 1. 0.650 0.10 0.66 0.10 8º 0º QT240R R1.10/0905 H Max 8.20 5.59 0.38 7.49 1.85 - 0.25 0.86 0.20 8º ...
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... ORDERING INFORMATION QT240-ISS MARKING DIAGRAM xxxx = fab code lQ PART TEMP RANGE -40 - 85C QT240-IG © QRG xxxxR 1 10 PACKAGE SSOP-20 QT240R R1.10/0905 ...
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... NOTES lQ 11 QT240R R1.10/0905 ...
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The specifications set out in this document are subject to change without notice. All products sold and services supplied by QRG are subject to our Terms and Conditions of sale and supply of services which are available online at ...