sx8638 Semtech Corporation, sx8638 Datasheet - Page 75

• Manufacturer Part Number: sx8638
• Description: Low Power, Capacitive Button And Slider Touch Controller 8 Sensors With Enhanced Led Drivers And Proximity
• Manufacturer: Semtech Corporation

1. No finger
=> No proximity detected
=> All LEDs OFF
ADVANCED COMMUNICATIONS & SENSING
7.2 Example of Touch+Proximity Module
7.2.1
To demonstrate the proximity sensing feature of the SX863x family, a module has been designed and is illustrated
in figure below.
The touch button controller is running in stand-alone (ie without host) and uses the Autolight mode to turn LEDs
ON/OFF accordingly to the touch buttons and proximity sensing status.
7.2.2
Module operation can be seen as 5 steps which are described in figure below
Notes:
- For better user experience, bicolor LEDs have been used here but one could decide to design a module with
normal unicolor LEDs. In this case, step 3 above would simply consist in a higher (blue) intensity for the LED of
the button touched.
- For obvious demonstration purposes the overlay used here is transparent but in typical applications (TV,
Monitor, Set-top box, etc) the overlay would be opaque enough so that when LEDs are OFF (ie no proximity
detected) the PCB is not visible to the user.
7.2.3
The proximity sensing distance of detection has been measured in these conditions:
- CapProxEnable = ON
Revision 7_6, September 10
Overview
Operation
Performance
2. Finger approaches
=> Proximity detected
=> Blue LEDs turned ON
Figure 60 Touch+Proximity
Figure 59 Touch+Proximity
© 2010 Semtech Corp.
Low Power, Capacitive Button and Slider Touch Controller
3. Button touch
=> Orange LED turned ON
(blue+orange = pink)
(8 sensors) with Enhanced LED Drivers and Proximity
75
Module Operation
Module Overview
4. Button release
=> Orange LED turned
OFF
DATASHEET
www.semtech.com
5. Finger removed
=> No proximity detected
=> Blue LEDs turned OFF
SX8638