SX8645I05AWLTRT Semtech, SX8645I05AWLTRT Datasheet - Page 14

• Manufacturer Part Number: SX8645I05AWLTRT
• Description: 12-ch Capacitive Touch Solution (Button & Wheel)
• Manufacturer: Semtech

SX8645
Ultra Low Power, Capacitive Button and Wheel
Touch Controller (12 sensors) with Enhanced LED Drivers
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
3.5 Sensors on the PCB
The capacitive sensors are relatively simple copper areas on the PCB connected to the twelve SX8645 capacitive
sensor input pins (CAP0…CAP11).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 (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 four sensors for buttons
Figure 9 PCB top
(surrounded by a ground plane)
PCB top layer of one wheel using six sensors
Figure 10
(surrounded by ground plane)
Revision 7_5, February 10
© 2010 Semtech Corp.
www.semtech.com
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