ATQT600 Atmel, ATQT600 Datasheet - Page 40

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

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

10620D–AT42–04/09
Mutual-capacitance Zero-dimensional Sensors
4.2.4.3
4-8
Avoiding False Key Detection
To avoid false keys, use any of the following tricks:
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


In addition, keep to the following general guidelines:
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
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1. Watch out for time constants.
2. Behind from the point of view of touch.
Figure 4-9.a. 90° Crossing (Best)
Figure 4-9.c. X Under Ground Trace
Cross the X and Y traces as little as possible and then only at 90° (see
If the X and Y traces must run parallel to each other for a distance, separate the traces with a ground
trace. Where possible, use a ground trace that is twice as wide as the track-to-track gap 
(see
Consider routing the X traces behind ground planes
traces is minimized, even if the Y traces run close to the X traces adjacent to the ground flood 
(see
Route the Y traces completely behind
so they do not interact (see
Keep the X and Y traces thin where possible.
Route the Y traces farthest from touch where possible.
Generally, keep all the X traces together and all the Y traces together. This way the number of
potential false keys is substantially reduced.
Figure
Figure
Gaps are much bigger than a touch
Y
4-9.b).
4-9.c).
Y
X
X
Panel
Ground
Figure
Substrate
4-9.d).
(2)
the X traces if needed, or route the X and Y traces well apart
Figure 4-9.b. Separating ground Trace
Figure 4-9.d. Y Under X
(1)
. This means that the field between the X and Y
Y
Ground
Y
Figure
Touch Sensors Design Guide
Note:
Avoid long runs!
X
X
4-9.a).