QTouch Schematic and Layout Checklist [APPLICATION NOTE]
Atmel-42094C-QTouch-Schematic-and-Layout-Checklist-ApplicationNote_072014
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To increase the height of the Slider increase the number of interleaving teeth (don’t stretch
the same pattern).
Figure 3-10. Repeat Interleaving Pattern to Add Height to Slider
Figure 3-11. Repeat Interleaving Pattern to Add Height to Slider
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There are no switching traces/components under the Slider/Wheel
These can degrade the SNR and compromise the achievable resolution. This can manifest itself as jitter in the
reported touch co-ordinate and is not desirable.
•
There are no ground planes under the Slider/Wheel
Ground planes under the Slider/Wheel will load the sensor and make it less sensitive. Ground planes that
unevenly load some of the channels are worse than all the channels being equally loaded.
Although GND loading decreases sensitivity, it increases SNR and Signal stability which can
be useful in noisy environments.
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Medium/large spatially interpolated Wheels have segment width of 4mm or less
The segments need to be narrow to ensure that the finger interacts with more than one segment when touching
the slider. The regions between the segments must have curved interleaving teeth.
•
In a medium/large spatially interpolated Wheel the width of each interleaving ring is 5mm to 8mm
For increasing the diameter of the Wheel increase the number of interleaving rings rather than increasing the
width of the ring.