APPLICATIONS -

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Consumer appliances

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Medical fluid sensing

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Soil moisture sensing

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Process controls

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Vending machines

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Automotive fluids

DESCRIPTION -

The QT114 QuickLevel™ charge-transfer (“QT”) sensor IC is specifically designed to detect point level in fluids

and powders. It will project a sense field through almost any dielectric, like glass, plastic, or ceramic, to sense

level on the inside of a vessel, from its exterior. It has the unique capability of independently sensing two trip

points when used with structured electrodes having two tiers.

The QT114 does not have sensing timeouts, drift compensation, or other functions which would interfere with

level sensing. Its threshold levels are fixed, and the amount of signal required to exceed a threshold is dependent

on circuit gain and electrode size and loading, all of which are under the control of the designer.

The QT114 requires only a single inexpensive capacitor in order to function. One or two LEDs can also be added

to provide a visual sensing indication.

Power consumption is under 20mA in most applications, allowing operation from Lithium cells for many years. In

most cases the power supply needs only minimal regulation.

The QT114 employs numerous signal acquisition and processing techniques pioneered by Quantum. No external

switches, opamps, or other analog components aside from CS are required.

A unique feature is the 'slosh filter', a detection integrator which averages detections over a rolling 15 second

interval before activating or deactivating the OUT pins. This filter allows use of the QT114 with violently moving

fluids, for example in a moving vehicle, that would otherwise cause the outputs to flicker between two states.

The device also includes selectable output polarity, allowing both output lines to be made either active-high or

active-low. It also includes the Quantum-pioneered HeartBeat™ signal, allowing a host controller to monitor the

health of the QT114 continuously if desired. By using the charge transfer principle, the IC delivers a level of

performance clearly superior to older technologies. It is specifically designed to replace electromechanical

devices like float switches, thermistors, and conductance probes.

Quantum Research Group Ltd

Copyright © 1999 Quantum Research Group Ltd

R1.03

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Limit sensing of almost any fluid or powder

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2-Tier level sensor - Hi / Low limits with one probe

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Only one external part required - a 5¢ capacitor

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Uses internal probes or external electrodes

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Active high or active low outputs

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Slosh filter averages response of moving fluids

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LED drive capable on both outputs

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2.5 to 5V 20µA single supply operation

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HeartBeat™ health indicator on both outputs

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QT114-IS

QT114-D

QT114-S

8-PIN DIP

SOIC

AVAILABLE OPTIONS

QProx™ QT114

Sns2

Gnd

Sns1

Pol

Filt

Out2

Out1

Vcc

1

2

3

45

6

7

8