ATQT600 Atmel, ATQT600 Datasheet - Page 39

• 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

4.2.4
4.2.4.1
4.2.4.2
Touch Sensors Design Guide
Interconnection
X Routing
Y 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 or LED drive
signals.
X routing is not touch sensitive, and so X traces can be routed with ease on any layer of a PCB, including
the side nearest to touch. However, X routing must also take the Y routing into account.
Y routing must be more carefully considered, due to Cp build-up and the need to avoid an effect called
false key detection. Y routing is only very weakly touch sensitive, so it is good practice to run Y traces on
a layer that is far from touch.
The first factor, Cp build-up, is easily dealt with by avoiding routing Y traces over or close to ground
planes (or other power planes).
The second factor, false key detection, can occur wherever there is an interaction of the Y traces with the
X traces. Remember that anywhere where X and Y get close (less than 10 mm), and the field between
them is allowed to be influenced by touch, you have a potential key or at least a touch sensitive zone that
you do not expect (see
Figure 4-8.
1. High kHz to hundreds of kHz in particular.
Potential False Key
(1)
Potential False
Key Detection
switching transients should be routed well away from X traces as they can disturb
Figure
X Trace
4-8).
Y Trace
Mutual-capacitance Zero-dimensional Sensors
Overlying Panel
10620D–AT42–04/09
4-7