ATQT600 Atmel, ATQT600 Datasheet - Page 16
![KIT EVAL TOUCH FOR QT600](/photos/9/18/91802/qt600_sml.jpg)
ATQT600
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
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
ATQT600
Manufacturer:
Atmel
Quantity:
135
10620D–AT42–04/09
General Advice
2.3.4
2-6
PCB to Panel Bonding
Table 2-1. Relative Dielectric Constants for Materials (Continued)
A useful metric when dealing with panels of different thicknesses and materials is the sensitivity factor
(S), given by
Equation 2-4. Sensitivity Factor (S)
In the case of a stack of materials, the combined
Equation 2-5. Dielectric Constant (
As can be seen, very thick panels will greatly reduce the sensitivity factor. If you need to use materials
that are thicker than what is considered normal practice (for example, if you need to sense through a
20 mm glass panel or a 10 mm acrylic panel), then be very careful about anything that increases
parasitic loading to the rear of the sensor. 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).
Good contact between the substrate and the panel is essential for reliable performance. An unreliable
interface which can change by even 100 microns after being touched by a finger can cause
unacceptable signal fluctuations. Adhesives or compression mechanisms can be used to reliably
overcome these problems. Non-adhesive solutions can for example involve the use of co-convex
surfaces that are placed under preloaded pressure when clamped together, to ensure complete surface
mating.
Various methods have been used to mechanically clamp electrode substrates to panels, including heat
staking plastic posts, screws, ultrasonic welding, spring clips, non-conductive foam rubber pressing from
behind, etc.
Material
Pyrex Glass
Quartz
Rubber
FR4 (Glass Fiber + Epoxy)
PMMA (Polymethyl Methacrylate)
Typical PSA (Pressure Sensitive Adhesive)
Equation
S =
where:
1/S
where:
t is the thickness of the layer in question
n is the number of layers
Sum is the sum of all terms
STACK
r
is the dielectric constant of the layer in question
r
/ t
2-4.
= Sum(1/S
LAYER
r
) for a Stack of Materials
[n])
Dielectric Constant (
4.3 to 5.0
4.2 to 4.4
3
4.2
2.6 to 4
2.5 to 2.7
r
for the whole stack is given in
r
)
Touch Sensors Design Guide
Equation
2-5.