sx8639 Semtech Corporation, sx8639 Datasheet - Page 14

• Manufacturer Part Number: sx8639
• Description: Low Power, Capacitive Button And Wheel Touch Controller 8 Sensors With Enhanced Led Drivers And Proximity Sensing
• Manufacturer: Semtech Corporation

SX8639
Low Power, Capacitive Button and Wheel Touch Controller
(8 sensors) with Enhanced LED Drivers and Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
3.5 Sensors on the PCB
The capacitive sensors are relatively simple copper areas on the PCB connected to the eight SX8639 capacitive
sensor input pins (CAP0…CAP7).The sensors are covered by isolating overlay material (typically 1mm...3mm).
The area of a sensor is typically one square centimeter which corresponds about to the area of a finger touching
the overlay material.
The capacitive sensors can be setup as ON/OFF buttons for either touch or proximity sensing (see example
Figure 9) or arranged in a wheel configuration (see example Figure 10) for e.g. menu scrolling or volume control
applications.
layer of three touch buttons sensors
Figure 9 PCB top
surrounded by a proximity sensor
PCB top layer of one wheel using six sensors
Figure 10
(surrounded by ground plane)
Please refer to the layout guidelines application note [1], for more details.
Revision 7_8, September 10
© 2010 Semtech Corp.
www.semtech.com
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