SX8647 Datasheet, PDF (1/72 Pages) Semtech Corporation – Ultra Low Power, Capacitive Wheel Touch Controller (8 sensors) with Enhanced LED Drivers

SX8647
Ultra Low Power, Capacitive Wheel
Touch Controller (8 sensors) with Enhanced LED Drivers
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
GENERAL DESCRIPTION
The SX8647 is an ultra low power, fully integrated 8-
channel solution for capacitive touch wheel
applications. Unlike many capacitive touch solutions,
the SX8647 features dedicated capacitive sense
inputs (that requires no external components) in
addition to 8 general purpose I/O ports (GPIO). Each
GPIO is typically configured as LED driver with
independent PWM source for enhanced lighting
control such as intensity and fading.
The SX8647 includes a capacitive 10 bit ADC analog
interface with automatic compensation up to 100pF.
The high resolution capacitive sensing supports a
wide variety of touch pad sizes and shapes and
allows capacitive wheels to be created using thick
overlay materials (up to 5mm) for an extremely
robust and ESD immune system design.
The SX8647 incorporates a versatile firmware that
was specially designed to simplify capacitive touch
solution design and offers reduced time-to-market.
Integrated multi-time programmable memory
provides the ultimate flexibility to modify key firmware
parameters (gain, threshold, scan period, auto offset
compensation… ) in the field without the need for
new firmware development.
The SX8647 supports the 400 kHz I²C serial bus
data protocol and includes a field programmable
slave address. The tiny 4mm x 4mm footprint makes
it an ideal solution for portable, battery powered
applications where power and density are at a
premium.
TYPICAL APPLICATION CIRCUIT
KEY PRODUCT FEATURES
 Complete Eight Sensors Capacitive Touch Controller for a
Wheel
ƒ Pre-configured for a Wheel
ƒ 8 LED Drivers with Individual Intensity, Fading Control
and Autolight Mode
ƒ 256 steps PWM Linear and Logarithmic control
 High Resolution Capacitive Sensing
ƒ Up to 100pF of Offset Capacitance Compensation at
Full Sensitivity
ƒ Capable of Sensing through Overlay Materials up to
5mm thick
 Extremely Low Power Optimized for Portable Application
ƒ 8uA (typ) in Sleep Mode
ƒ 80uA (typ) in Doze Mode (Scanning Period 195ms)
ƒ 175uA (typ) in Active Mode (Scanning Period 30ms)
 Programmable Scanning Period from 15ms to 1500ms
 Auto Offset Compensation
ƒ Eliminates False Triggers due to Environmental
Factors (Temperature, Humidity)
ƒ Initiated on Power-up and Configurable Intervals
 Multi-Time In-Field Programmable Firmware Parameters
for Ultimate Flexibility
ƒ On-chip user programmable memory for fast, self
contained start-up
 "Smart" Wake-up Sequence for Easy Activation from Doze
 No External Components per Sensor Input
 Internal Clock Requires No External Components
 Differential Sensor Sampling for Reduced EMI
 400 KHz Fast-Mode I²C Interface with Interrupt
 -40°C to +85°C Operation
APPLICATIONS
 Notebook/Netbook/Portable/Handheld computers
 Cell phones, PDAs
 Consumer Products, Instrumentation, Automotive
ORDERING INFORMATION
Part Number
Temperature
Range
Package
SX8647I05AULTRT¹ -40°C to +85°C Lead Free MLPQ-UT28
1 _{3000 Units/reel}
* This device is RoHS/WEEE compliant and Halogen Free
Revision 7_6, February 10
© 2010 Semtech Corp.
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