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What is QT320-D?

This electronic component, produced by the manufacturer "Quantum", performs the same function as "2-CHANNEL PROGAMMABLE ADVANCED SENSOR IC".


QT320-D Datasheet PDF - Quantum

Part Number QT320-D
Description 2-CHANNEL PROGAMMABLE ADVANCED SENSOR IC
Manufacturers Quantum 
Logo Quantum Logo 


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LQ
QPROXQT320
2-CHANNEL PROGAMMABLE ADVANCED SENSOR IC
Two channel digital advanced capacitive sensor IC
Projects two ‘touch buttons’ through any dielectric
Cloning for user-defined sensing behavior
100% autocal - no adjustments required
Only one external capacitor per channel
User-defined drift compensation, threshold levels
Variable gain via Cs capacitor change
Selectable output polarities
Toggle mode / normal mode outputs
HeartBeat™ health indicator on outputs (can be disabled)
1.8 ~ 5V supply, 60µA
APPLICATIONS
Light switches
Industrial panels
Appliance control
Security systems
Access systems
Pointing devices
Computer peripherals
Entertainment devices
The QT320 charge-transfer (“QT’”) touch sensor chip is a self-contained digital IC capable of detecting near-proximity or
touch on two sensing channels. It will project sense fields through almost any dielectric, like glass, plastic, stone, ceramic,
and most kinds of wood. It can also turn small metal-bearing objects into intrinsic sensors, making them respond to proximity
or touch. This capability coupled with its ability to self calibrate continuously can lead to entirely new product concepts.
It is designed specifically for human interfaces, like control panels, appliances, security systems, lighting controls, or
anywhere a mechanical switch or button may be found; it may also be used for some material sensing and control
applications provided that the presence duration of objects does not exceed the recalibration time-out interval.
The IC requires only a common inexpensive capacitor per channel in order to function.
Power consumption and speed can be traded off depending on the application; drain can be as low as 60µA, allowing
operation from batteries.
The IC’s RISC core employs signal processing techniques pioneered by Quantum; these are specifically designed to make
the device survive real-world challenges, such as ‘stuck sensor’ conditions and signal drift. Even sensitivity is digitally
determined. All key operating parameters can be set by the designer via the onboard eeprom which can be configured to alter
sensitivity, drift compensation rate, max on-duration, output polarity, and toggle mode independently on each channel.
No external switches, opamps, or other analog components aside from Cs are usually required.
The Quantum-pioneered HeartBeat™ signal is also included, allowing a host controller to monitor the health of the QT320
continuously if desired; this feature can be disabled via the cloning process.
By using the charge transfer principle, the IC delivers a level of performance clearly superior to older technologies in a highly
cost-effective package.
AVAILABLE OPTIONS
TA
00C to +700C
-400C to +850C
SOIC
-
QT320-IS
8-PIN DIP
QT320-D
-
LQ
Copyright © 2002 QRG Ltd
QT320/R1.03 08/02

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QT320-D equivalent
Figure 1-7 Burst lengths without Csx installed
(observed using a 750K resistor in series with probe)
Figure 1-8 Burst lengths with Csx installed
(observed using a 750K resistor in series with probe)
strength, even if the fiber density is too low to make the
plastic electrically conductive.
1.4.2 DECREASING SENSITIVITY
In some cases the circuit may be too sensitive, even with high
signal threshold values. In this case gain can be lowered by
making the electrode smaller, using sparse mesh with a high
space-to-conductor ratio (Figure 1-3), and most importantly by
decreasing Cs. Adding Cx capacitance will also decrease
sensitivity.
It is also possible to reduce sensitivity by making a capacitive
divider with Cx by adding a low-value capacitor in series with
the electrode wire.
1.4.3 HYSTERESIS
Hysteresis is required to prevent chattering of the output lines
with weak, noisy, or slow-moving signals.
The hysteresis can be set independently per channel.
Hysteresis is a reference-based number; thus, a threshold of
10 with a hysteresis of 2 will yield 2 counts of hysteresis
(20%); the channel will become active when the signal equals
or exceeds a count of 10, and go inactive when the count falls
to 7 or lower.
Hysteresis can also be set to zero (0), in which case the
sensor will go inactive when the count falls to 9 or lower in the
above example.
Threshold levels of under 4 counts are hard to deal with as
the hysteresis level is difficult to set properly.
1.4.4 CHANNEL BALANCE
Channel 1 has less internal Cx than Channel 2, which makes
it more sensitive than Channel 2 given equal Cx loads and Cs
capacitors. This can be useful in some designs where one
more sensitive channel is desired, but if equal sensitivity is
required a few basic rules should be followed:
1. Use a symmetrical PCB layout for both channels: Place
the IC half way between the two electrodes to match Cx
loading. Avoid routing ground plane (or other traces) close
to either sense line or the electrodes; allow 4-5 mm
clearance from any ground or other signal line to the
electrodes or their wiring. Where ground plane is required
(for example, under and around the QT320 itself) the
sense wires should have minimized adjacency to ground.
2. Connect a small capacitor (~5pF) between S1a or S1b
(either Channel 1 pin) and circuit ground (Csx in Figure
1-6), this will increase the load capacitance of Channel 1,
thus balancing the sensitivity of the two channels (see
Figures 1-7, 1-8).
3. Adjust Cs and/or the internal threshold of the two channels
until the sensitivities of the two channels are
indistinguishable from each other.
Since the actual burst length is proportional to sensitivity, you
can use an oscilloscope to balance the two channels with
more accuracy than by empirical methods (See Figures 1-7
and 1-8). Connect one scope probe to Channel 1 and the
other to Channel 2, via large resistors (750K ohms) to avoid
disturbing the measurement too much, or, use a low-C FET
probe. The Csx balance capacitor should be adjusted so that
the burst lengths of Channels 1 and 2 look nearly the same.
With some diligence the PCB can also be designed to include
some ground plane nearer to Channel 1 traces to induce
about 5pF of Csx load without requiring an actual discrete
capacitor.
lQ
5
QT320/R1.03 08/02


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On this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for QT320-D electronic component.


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Featured Datasheets

Part NumberDescriptionMFRS
QT320-DThe function is 2 CHANNEL PROGAMMABLE ADVANCED SENSOR IC. ETCETC
QT320-DThe function is 2-CHANNEL PROGAMMABLE ADVANCED SENSOR IC. QuantumQuantum
QT320-ISThe function is 2 CHANNEL PROGAMMABLE ADVANCED SENSOR IC. ETCETC

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