ATQT600 Atmel, ATQT600 Datasheet

KIT EVAL TOUCH FOR QT600

ATQT600

Manufacturer Part Number
ATQT600
Description
KIT EVAL TOUCH FOR QT600
Manufacturer
Atmel
Series
QTouch™r
Datasheets

Specifications of ATQT600

Sensor Type
Touch Screen
Interface
USB
Embedded
Yes, Other
Utilized Ic / Part
ATtiny88, ATmega324PA, ATxmega128A1
Processor To Be Evaluated
ATtiny88, ATmega324, ATxmega128
Data Bus Width
8 bit, 16 bit
Interface Type
USB
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Operating Supply Voltage
1.6 V to 3.6 V
Silicon Manufacturer
Atmel
Kit Application Type
Sensor
Application Sub Type
Touch Sensor
Kit Contents
USB Bridge, MCU Cards, Touchpad Cards
Svhc
No SVHC (15-Dec-2010)
Mcu Supported Families
ATtiny88,
Rohs Compliant
Yes
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Supply
-
Sensitivity
-
Sensing Range
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATQT600
Manufacturer:
Atmel
Quantity:
135
Touch Sensors
....................................................................................................................
Design Guide
10620D–AT42–04/09

Related parts for ATQT600

ATQT600 Summary of contents

Page 1

Touch Sensors .................................................................................................................... Design Guide 10620D–AT42–04/09 ...

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Touch Sensors Design Guide ...

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Table of Contents Section 1 Introduction To Sensor Design................................................................................... 1-1 1.1 Introduction ........................................................................................................................ 1-1 1.2 Self-capacitance and Mutual-capacitance Type Sensors .................................................. 1-1 1.3 Dimension Groups ............................................................................................................. 1-2 1.4 Some Important Theory ..................................................................................................... 1-2 Section 2 General Advice........................................................................................................... 2-1 2.1 Charge ...

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Table of Contents (Continued) 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 3.3.7 Section 4 Mutual-capacitance Zero-dimensional Sensors ......................................................... 4-1 4.1 Introduction ........................................................................................................................ 4-1 4.2 Planar Construction ........................................................................................................... 4-1 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.2.7 4.2.8 4.3 Non-Planar Construction.................................................................................................. 4-10 4.3.1 4.3.2 ...

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Typical Resistively Interpolated Method ............................................................................ 5-6 5.4.1 Section 6 Mutual-capacitance One-dimensional Sensors.......................................................... 6-1 6.1 Introduction ........................................................................................................................ 6-1 6.2 General Advice .................................................................................................................. 6-1 6.2.1 6.2.2 6.2.3 6.2.4 6.3 Typical Spatially Interpolated Method ................................................................................ 6-2 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 ...

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Touch Sensors Design Guide ...

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... You should also refer to QTAN0032, Designing Products with Atmel Capacitive Touchscreen ICs for an overview on designing capacitive touchscreens. ...

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... The combinations for zero-dimensional and one-dimensional sensors are discussed individually in are not covered by this guide. For information on designing two-dimensional sensors, please contact Atmel’s Touch Technology Division. Figure 1-1. Sensor Dimensions Zero Dimensional Sensors ...

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Capacitance (C) is defined in Equation 1-1. Capacitance It should therefore be clear that thinner panels and higher dielectric constant materials yield higher capacitance change during touch and hence a higher gain and a better SNR. Materials” on page 2-5 ...

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Introduction To Sensor Design Figure 1-3. Touch Signal Levels Touch Strength 1-4 10620D–AT42–04/09 Signal Untouched Touched Signal Touched Touch Sensors Design Guide ...

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... Charge Transfer Atmel’s capacitive sensors work on a principle called charge transfer. This uses a switched capacitor technique to assess relative changes in a sensor’s capacitance touched. Charge transfer works by applying a voltage pulse to series connection of the unknown capacitance Cx and a charge integrator capacitor Cs. By repeating the pulse multiple times, a high resolution ...

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General Advice Figure 2-1. Measuring the Charge-transfer Pulses Figure 2-2. Good and Bad Charge Pulses As a rule, the overall RC time constant of each sensor should be reduced as far as possible, while trying to preserve at least a ...

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... If this kind of effect is suspected, try changing to another brand of capacitor for Cs. Some modern Hi-K ultra-small X5R capacitors (for example, 0201 size) have been shown to demonstrate such behavior. However, it has not been seen by Atmel as a significant effect for 0402, 0603, 0805 sized components. ...

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General Advice Placing the passive components close to the chip, whilst having a long set of tracks to the chip from the key, negates the desired result, as long tracks act as RF antennas. The series resistor acts to reduce ...

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It is acceptable to use a flex PCB or FFC/FPC certain that it will be mechanically stable for the intended uses of the product. The traces running in the flex will be part of the touch sensor the ...

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... More on this in later sections. When designing a decorated front panel, be aware that some paints and finishes can be substantially conductive (refer to QTAN0021, Materials and Coatings Selection for Atmel Capacitive-touch Panels, for more information). 2.3.4 PCB to Panel Bonding Good contact between the substrate and the panel is essential for reliable performance ...

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The most common form of electrode is a filled circle or rectangle of copper on a PCB, corresponding loosely in shape to the key graphic. The PCB is then usually glued with an industrial adhesive such as a two-sided acrylic ...

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... Electrostatic Discharge Protection In general, Atmel capacitive sensors do not need extra ESD protection on their electrodes or traces. Normally, the touch sensor is located behind a dielectric panel that has a breakdown potential of tens of kilovolts per mm of thickness. The single greatest threat from ESD tends to occur where there is a gap or hole in the panel, particularly at the edge of the panel. In these situations an effect known as " ...

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Figure 2-5. Effect of ESD Creepage On a Flex Tail Under extreme circumstances capacitance ( less) varistors or transient suppressor devices near to the control chip. If the creepage path is "broken" before the ESD meets the sensor, ...

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General Advice 2-10 10620D–AT42–04/09 Touch Sensors Design Guide ...

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... The electrode “back-fires” its electric field through the PCB, the adhesive layer, and the panel. Atmel’s QT devices are unique in having a sufficient signal range to detect through thick panel construction, and yet remain highly reliable and sensitive ( common stack thickness for QT sensor circuits) ...

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Self-capacitance Zero-dimensional Sensors 3.2.2 Electrode Shapes An electrode is simply the patch of conductive material on the substrate that forms the sensor. Common shapes are filled discs, squares and rectangles (see Figure 3-2. Common Electrode Shapes It is also possible ...

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Ground Loading This style of sensor is highly sensitive to ground loading because such loading adds directly to Cx, thus reducing the sensor’s gain. Any signal or power rail that runs under, or close to, the electrode will reduce ...

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Self-capacitance Zero-dimensional Sensors Figure 3-5. A Ground Flood Near To a Sensor While the ground flood shown in Figure 3 effective approach, it should be remembered that ground areas near the key also increase the capacitive loading ...

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Figure 3-6. Spacing of Adjacent Traces Gap of at least ½T between the two traces ³½ important to note that interconnecting traces should not be run over ground or power planes where possible, especially when the separation to ...

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... Another common method of backlighting is to use a light spreader sheet with side illumination and controlled light leakage areas above the keys (see illuminated structures. Electroluminescent lamps have also been successfully used with Atmel’s capacitive sensors, but this is a much more complex topic and is beyond the scope of this document. Figure 3-8. ...

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... Conductive Paints Refer to QTAN0021, Materials and Coatings Selection for Atmel Capacitive-touch Control Panels (available under a non-disclosure agreement only), for details of selecting conductive paints and coatings. 3.3 ...

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... The Philipp spring technology is available under license. Please consult Atmel for the licensing options on this technology. For advice on suitable sources of springs, contact Atmel’s Touch Technology Division. ...

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Figure 3-11. Philipp Spring Products Using a conventional spring may also work, but it tends to result in low sensitivity keys and a poor SNR, due to the low surface area of the top of the spring. Figure 3-12. Compressing ...

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Self-capacitance Zero-dimensional Sensors 3.3.3 Secondary Substrate Method Another option is to form the electrodes on a secondary PCB, flex, or similar substrate. This can then be bonded to the front panel and interconnected to the control chip by a separate ...

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Figure 3-14. Using LEDs with Philipp Spring Products 3.3.6 Floating Conductive Items The considerations for the use of floating conductive items described in Conductive Items” on page 3-6 3.3.7 Conductive Paints The considerations for the use of conductive paints described ...

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Self-capacitance Zero-dimensional Sensors 3-12 10620D–AT42–04/09 Touch Sensors Design Guide ...

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Mutual-capacitance Zero-dimensional Sensors 4.1 Introduction This section describes how you design zero-dimensional sensors using a mutual-capacitance implementation (see implement keys for use with QMatrix sensor controllers. As with a self-capacitance zero-dimensional type sensor, the guidelines for constructing a mutual- capacitance ...

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Mutual-capacitance Zero-dimensional Sensors 4.2.2 X and Y Electrodes 4.2.2.1 Interdigitating the X and Y Electrodes The X and Y electrodes are generally interdigitated, that is they form interlocking “fingers”. Typically the X electrode surrounds the Y electrode helps ...

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Coupling Length The goal with this interdigitated design is to optimize SNR by maximizing the coupling length the X and Y electrodes within the confines of the space allocated for the key. The coupling length is determined by a ...

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Mutual-capacitance Zero-dimensional Sensors Figure 4-3. Results of Example Calculation 4.2.2.8 Designs Resulting In Low Interdigitation As has already been stated, designs that result in a very small number of fingers should be avoided, as such designs result in a poor ...

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Figure 4-4. Example Resulting In Low Interdigitation Due to the key size and panel thickness, the resulting key is far from ideal and has a lack of interdigitation – there is only one X finger! Such a low degree of ...

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Mutual-capacitance Zero-dimensional Sensors 4.2.3 Ground Loading One big advantage of a mutual-capacitance sensor is that because the coupling capacitance from being measured, any parasitic effects are not so acute as they are ...

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Interconnection 4.2.4.1 X Routing X routing is fairly trivial as long as RC time constant rules are observed. Nearby foreign signals that have large kHz frequency the charge transfer. Examples of circuits to consider include D-class amplifier signals, LCD ...

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Mutual-capacitance Zero-dimensional Sensors 4.2.4.3 Avoiding False Key Detection To avoid false keys, use any of the following tricks:  Cross the X and Y traces as little as possible and then only at 90° (see  If the X and ...

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Illumination Effects With the planar construction of mutual-capacitance type electrodes it is fine to make holes in the X portion of the electrode to allow light to shine though, much as described in Effects” on page Try not to ...

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Mutual-capacitance Zero-dimensional Sensors 4.3 Non-Planar Construction 4.3.1 Introduction It is often desirable to form electrodes on the inner surface of a panel that is not part of the main capacitive touch circuit board. This technique can be used with a ...

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With the flooded-X two-layer method the X and Y electrodes are designed to overlap each other, with the Y electrode nearest to touch. The X electrode must be separated some distance below the Y electrode and be larger and of ...

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Mutual-capacitance Zero-dimensional Sensors 4.3.3 Spring Method A useful method for transferring the touch-sensitive region of a mutual-capacitance sensor use a conductive spring or hollow conductive tube to act emitter, with the Y electrode placed centrally ...

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Adapting the Planar Construction For Distribution Across Two Layers For completeness worth noting that the planar construction detailed in be distributed across two layers if desired; it may, for example, make the layout and interconnections easier. Generally, ...

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Mutual-capacitance Zero-dimensional Sensors 4-14 10620D–AT42–04/09 Touch Sensors Design Guide ...

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Introduction This section describes how you design one-dimensional sensors using a self-capacitance implementation (see implement sliders or wheels for use with QTouch sensor controllers. Note that three active channels are used in all the cases described in this section. ...

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Self-capacitance One-dimensional Sensors If this is not possible, and the connecting traces have to be routed on the same layer as the electrodes themselves, always escape the traces as quickly as possible out of the touch area; then regroup the ...

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Typical Spatially Interpolated Method 5.3.1 Introduction A spatially interpolated wheel or slider sensor uses three electrodes, all directly connected to the sensor chip. The form of the electrodes depends on the overall size of the slider or wheel. Note ...

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Self-capacitance One-dimensional Sensors Figure 5-3. Small Wheel (Spatially Interpolated) 5.3.3 Medium/Large Slider Or Wheel In the context of this document, a medium/large slider is between 26 and 60 mm long and a medium/large wheel is between 20 and 60 mm ...

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Figure 5-4. Medium/Large Slider (Spatially Interpolated) Channel 0 Make all sections equal width, repeating sections as required for desired total width Figure 5-5. Medium/Large Wheel (Spatially Interpolated) Note: Make all the rings equal width, repeating rings as required for desired ...

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... Resistors R1 and R2 form a “dead band” at the each end to stop end wrap-around. Make them approximately 5 percent of Rtotal to achieve a 5 percent band at each end. Note that not all Atmel slider chips need these. The sensor design for medium/large wheels is essentially the same as that for sliders, but with the ...

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Figure 5-7. Medium/Large Wheel (Resistively Interpolated) Rtotal typically 100 kW Touch Sensors Design Guide Channel 0 5–9 mm Channel 2 120° Self-capacitance One-dimensional Sensors Fill with segments Parallel Gap on equal spacing, 0.1–0.5 mm adjusting width to suit Outer Arc ...

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Self-capacitance One-dimensional Sensors 5-8 10620D–AT42–04/09 Touch Sensors Design Guide ...

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Mutual-capacitance One-dimensional Sensors 6.1 Introduction This section describes how you design one-dimensional sensors using a mutual-capacitance implementation (see implement sliders or wheels for use with QMatrix sensor controllers. As with self-capacitance one-dimensional sensors, two types of sensors can be considered: ...

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Mutual-capacitance One-dimensional Sensors 6.3 Typical Spatially Interpolated Method 6.3.1 Introduction This method uses an array of keys directly adjacent to each other. 6.3.2 One-Layer Small Slider Or Wheel 6.3.2.1 Slider There are numerous ways to construct a spatially interpolated slider, ...

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To design the slider: 1. Decide on the length of your slider (L). 2. Apply the rules in X and X fingers Equation 6-8. Calculation for X 3. Check that the width (W) of each key in the slider is ...

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Mutual-capacitance One-dimensional Sensors 6.3.2.2 Wheel The sensor design for a wheel is essentially the same as that for the slider, but the array of keys are arranged in a circular form (see wheels from ...

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Apply the rules in X (see fingers Equation 6-9. Calculation for X 4. Determine where the gaps between the keys occur by calculating the number of X fingers in each key (X / keys). fingers You can now draw ...

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Mutual-capacitance One-dimensional Sensors 6.3.4 Two-Layer Small Slider Or Wheel 6.3.4.1 Introduction This sensor style uses a Flooded X design (see 10) and can operate with 3 or more channels. The basic layout rules listed in do the layer separation rules. ...

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Wheel To form a wheel, the design is simply is wrapped around to form a circle, with the X segments becoming wedge shaped (see many Y “circles” as necessary to ensure a maximum gap between them. ...

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Mutual-capacitance One-dimensional Sensors 6.3.5 Two-layer Medium/Large Slider Or Wheel 6.3.5.1 Introduction When construcing two-layer medium/large sliders and wheels the electrodes are constructed from slanted “segments”. 6.3.5.2 Slider For a slider, each “segment” high, and the slider is ...

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Wheel To form a wheel, the design is wrapped around to form a circle, the X segments becoming curved tooth shapes (see Figure 6-7 on page Figure 6-7. Two-layer Medium/Large Wheel (Spatially Interpolated) X Electrodes x n Touch Sensors ...

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Mutual-capacitance One-dimensional Sensors 6.4 Typical Resistively Interpolated Method 6.4.1 Introduction This method uses an array of key segments connected by resistors. The advantage of this method is that each key (or channel) in the sensor is formed by one or ...

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Two-Layer Medium/Large Slider Or Wheel Creating larger sliders and wheels when using a flooded X design follows the same principles as in Section 6.3.5 “Two-layer Medium/Large Slider Or Wheel” on page introduced using resistive dividers on the X lines. ...

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Mutual-capacitance One-dimensional Sensors 6-12 10620D–AT42–04/09 Touch Sensors Design Guide ...

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Channel One of the capacitive measurement point at which the sensor controller can detect capacitive change. See also node. Electrode The patch of conductive material on the substrate that forms the sensor. An electrode is usually (but not always) made ...

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Glossary of Terms Linearity The measurement of the peak-to-peak deviation of the reported touch coordinate in one axis relative to the absolute position of touch on that axis. This is often referred to as the nonlinearity. Nonlinearities in either X ...

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Planar Construction A method of construction in which the electrodes and the traces for the sensor are fabricated on the same plane of the insulating substrate (for example, a PCB or Flex PCB). See page 3-1. See also non-planar construction. ...

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Glossary of Terms A-4 10620D–AT42–04/09 Touch Sensors Design Guide ...

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Revision History Revision No. Revision A – December 2008 Revision B – January 2009 Revision C – February 2009 Revision D – April 2009 Touch Sensors Design Guide History  Initial version.  Updates to advice on interdigitated electrodes.  ...

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... Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDI- TIONS OF SALE LOCATED ON ATMEL’S WEB SITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ...

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