NT1160 Datasheet, PDF (8/22 Pages) List of Unclassifed Manufacturers – The Nuvoton touch key series

NT1160
4.2 Sensor Pad and Ground for PCB Layout
The size of sensor pad, using circular shape with diameter equal or greater than 8mm is
recommended. Actually, sensor pad could be any kinds of shape, but fulfilling finger size is suitable.
Extra ground-net around sensor pads is not needed for PCB artwork. However, ground-net along
sensor pad to chip is alternative. Figure 4-3 shows that the PCB line width of sensor pad to chip
should be 0.254mm (10mil) or less and to keep distance with ground at least 1mm. The other layer
of PCB could implement ground-net for PCB artwork to block noise interfering with signal line. All
the subsidiary components need to be kept as close to sensor pad as possible at PCB layout.
Meanwhile, the touch key chip (NT1160) and touch pad located on the same PCB board would be
better.
0.254mm(10mil)
Sensor
Pad
GND
GND
>1mm
>1mm
Figure 4-3 Sensor Pad and Ground-Net
As shown in Figure 4-4, a spring attached to the metal-panel can be used as a sensor pad. It is
recommended that the metal-panel (ring) should be adhered to the inside of cover to be an effective
sensing area. If user wants to add a LED in the middle of sensor pad, the measure of sensor area
should be increased to compensate the hollowing part and keeping the same sensitivity.
Figure 4-4 Spring with Solid Metal Plane/Ring
4.3 Sensor Pad Size
The size of sensor pad plays a significant role in determining the thickness of panel. The greater
area of a sensor pad is, the deeper a touch signal could be detected. Table 4-1 shows the
relationship between the pad size and panel thickness.
Size of Sensor Pad
Mar 12, 2016
Panel Thickness
(Recommended Value)
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Rev 1.00