sx8636 Semtech Corporation, sx8636 Datasheet - Page 10

• Manufacturer Part Number: sx8636
• Description: Low Power, Capacitive Button Touch Controller 8 Sensors With Enhanced Led Drivers And Proximity Sensing
• Manufacturer: Semtech Corporation

ADVANCED COMMUNICATIONS & SENSING
3 F
3.1 Quickstart Application
The SX8636 is preconfigured (Quickstart Application) for an application with eight buttons and eight LED drivers
using logarithmic PWM fading.
Implementing a schematic based on Figure 6 will be immediately operational after powering without programming
the SX8636 (even without host).
Touching the sensor on the CAP0 pin will enable automatically the LED connected to GPIO0. When the CAP0
sensor is released the LED on GPIO0 will slowly fade-out using smooth logarithmic fading.
All other sensors (CAP1 to CAP7) have their own LED associated on a GPIO pin showing a touch or a release.
The sensor detection and the LED fading described above are operational without any host interaction.
This is made possible using the SX8636 Autolight feature described in the following sections.
3.2
3.2.1
The SX8636 is intended to be used in applications which require capacitive sensors covered by isolating overlay
material and which need to detect the proximity of a finger/hand though the air. A finger approaching the
capacitive sensors will change the charge that can be loaded on the sensors. The SX8636 measures the change
of charge and converts that into digital values (ticks). The larger the charge on the sensors, the larger the number
of ticks will be. The charge to ticks conversion is done by the SX8636 Analog Sensor Interface (ASI).
The ticks are further processed by the SX8636 and converted in a high level, easy to use information for the
user’s host.
The information between SX8636 and the user’s host is passed through the I2C interface with an additional
interrupt signal indicating that the SX8636 has new information. For buttons this information is simply touched or
released.
Revision 7_5, September 10
UNCTIONAL DESCRIPTION
Introduction
General
d0
d1
d2
d3
d4
d5
d6
d7
cap0
cap1
cap2
cap3
cap4
cap5
cap6
cap7
interface
analog
sensor
Figure 6
generation
processor
micro
clock
RAM
ROM
power management
RC
© 2010 Semtech Corp.
Low Power, Capacitive Button Touch Controller (8 sensors)
controller
controller
Quickstart Application
PWM
GPIO
NVM
SX8636
LED
I2C
with Enhanced LED Drivers and Proximity Sensing
10
gnd
gpo5
gpo4
gpo3
gpo2
gnd
gpo1
gpo0
bottom plate
d7
d5
d3
d1
d0
d6
d4
d2
HOST
DATASHEET
www.semtech.com
SX8636