QT150 Datasheet PDF - QUANTUM


www.Datasheet-PDF.com

QT150
QUANTUM

Part Number QT150
Description (QT140 / QT150) 4 AND 5 KEY QTOUCH SENSOR ICs
Page 14 Pages

QT150 datasheet pdf
View PDF for PC
QT150 pdf
View PDF for Mobile


No Preview Available !

www.DataSheet4U.com
lQ
QProx™ QT140 / QT150
4 AND 5 KEY QTOUCHSENSOR ICs
Completely independent QT touch circuits
Individual logic outputs per channel (open drain)
Projects prox fields through any dielectric
Only one external capacitor required per channel
Sensitivity easily adjusted on a per-channel basis
100% autocal for life - no adjustments required
3~5.5V, 5mA single supply operation
Toggle mode for on/off control (strap option)
10s, 60s, infinite auto-recal timeout (strap options)
AKS™ Adjacent Key Suppression (pin option)
Sync pin for multi-chip sync or line sync
Less expensive per key than many mechanical switches
Eval board with backlighting - p/n E160
SSOP
DIP
Vss
Vss
Vdd
Vdd
SNS1A
SNS1B
SNS2A
SNS2B
SNS3A
SNS3B
SNS4A
SNS4B
SNS5A
Vss
/RST
OSC_I
OSC_O
OPT2
OPT1
SYNC
OUT5
OUT4
OUT3
OUT2
OUT1
AKS
OC
SNS5B
Vdd
Vdd
Vss
Vss
Vss
SNS1A
SNS1B
SNS2A
SNS2B
SNS3A
SNS3B
SNS4A
SNS4B
SNS5A
/RST
OSC_I
OSC_O
OPT2
OPT1
SYNC
OUT5
OUT4
OUT3
OUT2
OUT1
AKS
OC
SNS5B
QT150 shown - NOTE: Pinouts are not the same!
APPLICATIONS
PC Peripherals
Backlighted buttons
Appliance controls
Security systems
Access systems
Pointing devices
Instrument panels
Gaming machines
QT140 / QT150 charge-transfer (“QT’”) QTouch ICs are self-contained digital controllers capable of detecting near-proximity or
touch on 4 or 5 electrodes. They allow electrodes to project independent sense fields through any dielectric like glass, plastic,
stone, ceramic, and wood. They can also turn metal-bearing objects into intrinsic sensors, making them responsive to proximity
or touch. This capability coupled with their continuous self-calibration feature can lead to entirely new product concepts, adding
high value to product designs.
Each of the channels operates independently of the others, and each can be tuned for a unique sensitivity level by simply
changing its sample capacitor value.
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.
These devices require only a common inexpensive capacitor per sensing channel in order to function. They also offer patent
pending AKS™ Adjacent Key Suppression which suppresses touch from weaker responding keys and allows only a dominant
key to detect, for example to solve the problem of large fingers on tightly spaced keys.
These devices also have a SYNC I/O pin which allows for synchronization with additional similar parts and/or to an external to
suppress interference.
The RISC core of these devices use signal processing techniques pioneered by Quantum which are designed to survive
numerous real-world challenges, such as ‘stuck sensor’ conditions, component ageing, moisture films, and signal drift.
By using the charge transfer principle, these devices deliver a level of performance clearly superior to older technologies yet
are highly cost-effective.
TA
00C to +700C
-400C to +1050C
00C to +700C
-400C to +1050C
LQ
AVAILABLE OPTIONS
SSOP-28
-
QT140-AS
-
QT150-AS
DIP-28
QT140-D
-
QT150-D
-
Copyright © 2002 QRG Ltd
QT140/150 1.01/1102



No Preview Available !

Table 1-1 Pin Listing
QT140 / QT150 SSOP-28
Pin Name Description
1 Vss
Negative power (Ground)
2 Vss
Negative power (Ground)
3 Vdd
Positive power
4 Vdd
Positive power
5 SNS1A
Sense pin (to Cs1, electrode)
6 SNS1B
Sense pin (to Cs1)
7 SNS2A
Sense pin (to Cs2, electrode)
8 SNS2B
Sense pin (to Cs2)
9 SNS3A
Sense pin (to Cs3, electrode)
10 SNS3B
Sense pin (to Cs3)
11 SNS4A
Sense pin (to Cs4, electrode)
12 SNS4B
Sense pin (to Cs4)
13 NC/SNS5A Sense pin (to Cs5, electrode) n/c on QT140
14 Vss
Supply negative rail (ground)
15 NC/SNS5B Sense pin (to Cs5) n/c on QT140
16 OC
Output Option (input pin; 1= open drain)
17 AKS
Adjacent Key Suppression Opt. (input; 1=AKS)
18 OUT1
Channel 1 output, o-d or p-p
19 OUT2
Channel 2 output, o-d or p-p
20 OUT3
Channel 3 output, o-d or p-p
21 OUT4
Channel 4 output, o-d or p-p
22 NC/OUT5 Channel 5 output, o-d or p-p (n/c on QT140)
23 SYNC
Synchronization pin (I/O pin - pull high with 10K)
24 OPT1
Option Mode (Input pin - see Table 2-1)
25 OPT2
Option Mode (Input pin - see Table 2-1)
26 OSC_O
27 OSC_I
Oscillator output
Oscillator input
28 /RST
Reset pin (active low input)
QT140 / QT150 DIP-28
Pin Name Description
1 Vdd
Positive power
2 Vdd
Positive power
3 Vss
Negative power (Ground)
4 Vss
Negative power (Ground)
5 Vss
Negative power (Ground)
6 SNS1A
Sense pin (to Cs1, electrode)
7 SNS1B
Sense pin (to Cs1)
8 SNS2A
Sense pin (to Cs2, electrode)
9 SNS2B
Sense pin (to Cs2)
10 SNS3A
Sense pin (to Cs3, electrode)
11 SNS3B
Sense pin (to Cs3)
12 SNS4A
Sense pin (to Cs4, electrode)
13 SNS4B
Sense pin (to Cs4)
14 NC/SNS5A Sense pin (to Cs5, electrode) n/c on QT140
15 NC/SNS5B Sense pin (to Cs5) n/c on QT140
16 OC
Output Option (input pin; 1= open drain)
17 AKS
Adjacent Key Suppression Opt. (input ; 1=AKS)
18 OUT1
Channel 1 output, o-d or p-p
19 OUT2
Channel 2 output, o-d or p-p
20 OUT3
Channel 3 output, o-d or p-p
21 OUT4
Channel 4 output, o-d or p-p
22 NC/OUT5 Channel 5 output, o-d or p-p (n/c on QT140)
23 SYNC
Synchronization pin (I/O pin - pull high with 10K)
24 OPT1
Option Mode (Input pin - see Table 2-1)
25 OPT2
Option Mode (Input pin - see Table 2-1)
26 OSC_O
27 OSC_I
Oscillator output
Oscillator input
28 /RST
Reset pin (active low input)
1 - OVERVIEW
QT140/150 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.
Figures 1-6 and 1-7 show basic circuits for these devices.
See Table 1-1 for device pin listings.
Vss
Vss
Vdd
Vdd
SNS1A
SNS1B
SNS2A
SNS2B
SNS3A
SNS3B
SNS4A
SNS4B
NC
Vss
SSOP
/RST
OSC_I
OSC_O
OPT2
OPT1
SYNC
NC
OUT4
OUT3
OUT2
OUT1
AKS
OC
NC
DIP
Vdd
Vdd
Vss
Vss
Vss
SNS1A
SNS1B
SNS2A
SNS2B
SNS3A
SNS3B
SNS4A
SNS4B
NC
/RST
OSC_I
OSC_O
OPT2
OPT1
SYNC
NC
OUT4
OUT3
OUT2
OUT1
AKS
OC
NC
Fig 1-1 QT140 Pinouts
NOTE: SSOP / DIP Pinouts are not the same!
The DIP and SOIC pinouts are not the same and serious
damage can occur if a part is miswired.
1.1 BASIC OPERATION
The devices employ bursts of charge-transfer cycles to
acquire signals. Burst mode permits low power operation,
dramatically reduces RF emissions, lowers susceptibility to
RF fields, and yet permits excellent speed. Internally, signals
are digitally processed to reject impulse noise using a
'consensus' filter that requires three consecutive
confirmations of detection. Each channel is measured in
sequence starting with Channel 1.
The QT switches and charge measurement hardware
functions are all internal to the device. A single-slope
switched capacitor ADC includes the QT charge and transfer
switches in a configuration that provides direct ADC
conversion; an external Cs capacitor accumulates the charge
from sense-plate Cx, which is then measured.
Larger values of Cx cause the charge transferred into Cs to
rise more rapidly, reducing available resolution; as a
minimum resolution is required for proper operation, this can
result in dramatically reduced gain. Conversely, larger values
of Cs reduce the rise of differential voltage across it,
increasing available resolution by permitting longer QT
bursts. The value of Cs can thus be increased to allow larger
values of Cx to be tolerated. The IC is responsive to both Cx
and Cs, and changes in Cs can result in substantial changes
in sensor gain.
lQ
2 QT140/150 1.01/1102



No Preview Available !

Unused channels: If a channel is not used, a dummy sense
capacitor (nominal value: 1nF) of any type must be
connected between the unused SNSnA / SNSnB pins ensure
correct operation.
Unused pins: Unused device pins labeled NC should
remain unconnected.
1.2 ELECTRODE DRIVE
These devices have completely independent sensing
channels. The internal ADC treats Cs on each channel as a
floating transfer capacitor; as a direct result, sense
electrodes can be connected to either SNSnA or SNSnB and
the sensitivity and basic function will be the same; however
there is an advantage in connecting electrodes to SNSnA
lines to reduce EMI susceptibility.
The PCB traces, wiring, and any components associated
with or in contact with SNSnA and SNSnB will become touch
sensitive and should be treated with caution to limit the touch
area to the desired location.
Multiple touch electrodes connected to SNSnA can be used,
for example to create control surfaces on both sides of an
object.
It is important to limit the amount of stray capacitance on the
SNSnA and SNSnB terminals, for example by minimizing
trace lengths and widths to allow for higher gains and lower
values of Cs.
1.3 KEY DESIGN
1.3.1 KIRCHOFFS CURRENT LAW
Like all capacitance sensors, these parts rely on Kirchoffs
Current Law (Figure 1-2) to detect the change in capacitance
of the electrode. This law as applied to capacitive sensing
requires that the sensors field current must complete a loop,
returning back to its source in order for capacitance to be
sensed. Although most designers relate to Kirchoffs law with
regard to hardwired circuits, it applies equally to capacitive
field flows. By implication it requires that the signal ground
and the target object must both be coupled together in some
manner for a capacitive sensor to operate properly. Note that
there is no need to provide actual galvanic ground
connections; capacitive coupling to ground (Cx1) is always
Figure 1-2 Kirchoff's Current Law
CX2
sufficient, even if the coupling might seem very tenuous. For
example, powering the sensor via an isolated transformer will
provide ample ground coupling, since there is capacitance
between the windings and/or the transformer core, and from
the power wiring itself directly to 'local earth'. Even when
battery powered, just the physical size of the PCB and the
object into which the electronics is embedded will generally
be enough to couple a few picofarads back to local earth.
1.3.2 KEY GEOMETRY, SIZE, AND LOCATION
There is no restriction on the shape of the key electrode; in
most cases common sense and a little experimentation can
result in a good electrode design. The devices will operate
with long thin electrodes, round or square ones, or keys with
odd shapes. Electrodes can also be on 3-dimensional
surfaces. Sensitivity is related to the amount of electrode
surface area, overlying panel material and thickness, and the
ground return coupling quality of the circuit.
If a relatively large touch area is desired, and if tests show
that the electrode has more capacitance than the part can
tolerate, the electrode can be made into a sparse mesh
(Figure 1-3) having lower Cx than a solid plane.
Since the channels acquire their signals in time-sequence,
any of the electrodes can be placed in direct proximity to
each other if desired without cross-interference.
1.3.3 BACKLIGHTING KEYS
Touch pads can be back-illuminated quite readily using
electrodes with a sparse mesh (Figure 1-3) or a hole in the
middle (Figure 1-4). The holes can be as large as 4 cm in
diameter provided that the ring of metal is at least twice as
wide as the thickness of the overlying panel, and the panel is
greater than 1/8 as thick as the diameter of the hole. Thin
panels do not work well with this method as they do not
propagate fields laterally very well, and will have poor
sensitivity in the middle. Experimentation is required.
A good example of backlighting can be found in the E160
evaluation board.
1.3.4 VIRTUAL CAPACITIVE GROUNDS
When detecting human contact (e.g. a fingertip), grounding
of the person is never required. The human body naturally
has several hundred picofarads of free spacecapacitance
to the local environment (Cx3 in Figure 1-2), which is more
than two orders of magnitude greater than that required to
create a detection. The sensors PCB however may be
physically small, so there may be little free spacecoupling
(Cx1 in Figure 1-2) between it and the environment to
Figure 1-3 Mesh Electrode Geometry
S e nse E le ctro de
SENSOR
CX 1
Su rro und in g e nv iro nm en t
CX3
lQ
3 QT140/150 1.01/1102



No Preview Available !

Figure 1-4 Open Electrode for Back-Illumination
Figure 1-5 Shielding Against Fringe Fields
Sense
wire
Sense
w ire
complete the return path. If the circuit ground cannot be
earth grounded by wire, for example via the supply
connections, then a virtual capacitive groundmay be
required to increase return coupling.
A virtual capacitive groundcan be created by connecting
the IC's circuit ground to:
(1) A nearby piece of metal or metallized housing;
(2) A floating conductive ground plane;
(3) A larger electronic device (to which its output might be
connected anyway).
Free-floating ground planes such as metal foils should
maximize exposed surface area in a flat plane if possible. A
square of metal foil will have little effect if it is rolled up or
crumpled into a ball. Virtual ground planes are more effective
and can be made smaller if they are physically bonded to
other surfaces, for example a wall or floor.
1.3.5 FIELD SHAPING
The electrode can be prevented from sensing in undesired
directions with the assistance of metal shielding connected
to circuit ground (Figure 1-5). For example, on flat surfaces,
the field can spread laterally and create a larger touch area
than desired. To stop field spreading, it is only necessary to
surround the touch electrode on all sides with a ring of metal
connected to circuit ground. The ring will stop field spreading
from that point outwards.
If one side of the panel to which the electrode is fixed has
moving traffic near it, these objects can cause inadvertent
detections. This is called walk-byand is caused by the fact
that the fields radiate from either surface of the electrode
equally well. Again, shielding in the form of a metal sheet or
foil connected to circuit ground will prevent walk-by; putting
an air gap between the grounded shield and the electrode
will help to keep the value of Cx low.
1.3.6 SENSITIVITY
Sensitivity can be altered to suit various applications and
situations on a channel-by-channel basis. The easiest and
most direct way to impact sensitivity is to alter the value of
Cs; more Cs yields higher sensitivity.
1.3.6.1 Alternative Ways to Increase Sensitivity
Sensitivity can also be increased by using bigger electrodes,
reducing panel thickness, or altering panel composition.
Increasing electrode size can have diminishing returns, as
high values of Cx counteract sensor gain; however, Cs can
be increased to combat this up to the rated device limit. Also,
increasing the electrode's surface area will not substantially
increase touch sensitivity if its diameter is already much
larger in surface area than fingertip contact area.
The panel or other intervening material can be made thinner,
but again there are diminishing rewards for doing so. Panel
material can also be changed to one having a higher
dielectric constant, which will help propagate the field
through to the front. Locally adding some conductive material
to the panel (conductive materials essentially have an infinite
dielectric constant) will also help; for example, adding carbon
or metal fibers to a plastic panel will greatly increase frontal
field strength, even if the fiber density is too low to make the
plastic bulk-conductive.
1.3.6.2 Decreasing Sensitivity
In some cases the circuit may be too sensitive. Gain can be
lowered further by a number of strategies: a) making the
electrode smaller, b) making the electrode into a sparse
mesh using a high space-to-conductor ratio (Figure 1-3), or
c) by decreasing the Cs capacitors.
lQ
4 QT140/150 1.01/1102




QT150 datasheet pdf
Download PDF
QT150 pdf
View PDF for Mobile


Similiar Datasheets : QT100 QT1010 QT1080 QT1081 QT110 QT1100A-ISG QT1101 QT1103 QT1106-ISG QT110H QT111 QT112 QT113 QT113H QT114 QT115 QT117L QT118H QT118H-D QT118H-IS QT118H-S QT11x QT140 QT150 QT160 QT161

Index :   0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z   

This is a individually operated, non profit site. If this site is good enough to show, please introduce this site to others.
Since 2010   ::   HOME   ::   Privacy Policy + Contact