AN2869 Datasheet, PDF (21/43 Pages) STMicroelectronics – Guidelines for designing touch sensing applications

AN2869
Surface electrode design
3.3.2
Interlaced linear sensor
When using the charge transfer acquisition principle, it is possible to use only three
elements thanks to the higher resolution achieved. This sensor type is not compatible with
the RC acquisition principle due to the lower sensitivity supported.
Figure 14. Interlaced linear touch sensor with three elements (up to 60 mm long)
Full band width 3.6 mm
Electrode gap 0.2 - 0.3 mm
LEGEND:
Via between layers
10 % meshed ground plane
Copper electrode
1. The teeth of the interlaced linear touch sensor must be perfectly regular.
Tooth pitch
2.4 mm
Squared end
0.2 - 0.3 mm
Electrode/ground
gap 2 mm
ai15091
Doc ID 15298 Rev 6
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