lQ
"
"
"
"
"
"
"
"
"
"
Limit sensing of almost any fluid or powder
Two-tier level sensor - Hi / Low limits with one probe
Only one external part required - a 5¢ capacitor
Uses internal probes or external electrodes
Active high or active low outputs
Slosh filter averages response of moving fluids
LED drive capable on both outputs
2.5 to 5V 20µA single supply operation
HeartBeat™ health indicator on both outputs
RoHS compliant package
QT114
QL
EVEL
™ S
ENSOR
IC
Vcc
Out1
Out2
Filt
1
8
Gnd
Sns2
Sns1
Pol
QT114
2
3
4
7
6
5
APPLICATIONS -
!
Process controls
!
Vending machines
!
Consumer appliances
!
Automotive fluids
!
Medical fluid sensing
!
Soil moisture sensing
DESCRIPTION -
The QT114 QLevel™ 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.
T
A
0 C to +70
0
C
-40
0
C to +85
0
C
0
AVAILABLE OPTIONS
SOIC
-
QT114-ISG
8-PIN DIP
QT114-DG
-
l
q
Copyright © 1999-2006 QRG Ltd
QT114 R1.04/1106
QUALCOMM [ QUALCOMM INCORPORATED ]
