SX8639
Low Power, Capacitive Button and Wheel Touch Controller
(8 sensors) with Enhanced LED Drivers and Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
G
ENERAL
D
ESCRIPTION
The SX8639 is an ultra low power, fully integrated 8-
channel solution for capacitive touch-buttons and
wheel with proximity detection applications. Unlike
many capacitive touch solutions, the SX8639
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 SX8639 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 buttons to be created using thick
overlay materials (up to 5mm) for an extremely
robust and ESD immune system design.
The SX8639 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 SX8639 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.
DATASHEET
K
EY
P
RODUCT
F
EATURES
Complete Eight Sensors Capacitive Touch Controller for
Buttons and Wheel
Pre-configured for 4 Buttons and a Wheel
8 LED Drivers with Individual Intensity, Fading Control
and Autolight Mode
256 steps PWM Linear and Logarithmic control
Proximity Sensing up to several centimetres
High Resolution Capacitive Sensing
Up to 100pF of Offset Capacitance Compensation at
Full Sensitivity
Capable of Sensing through Overlay Materials up to
5mm thick
Extremely Low Power Optimized for Portable Application
8uA (typ) in Sleep Mode
80uA (typ) in Doze Mode (Scanning Period 195ms)
175uA (typ) in Active Mode (Scanning Period 30ms)
Programmable Scanning Period from 15ms to 1500ms
Auto Offset Compensation
Eliminates False Triggers due to Environmental
Factors (Temperature, Humidity)
Initiated on Power-up and Configurable Intervals
Multi-Time In-Field Programmable Firmware Parameters
for Ultimate Flexibility
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
T
YPICAL
A
PPLICATION CIRCUIT
A
PPLICATIONS
im
ity
d7
Notebook/Netbook/Portable/Handheld computers
d6
resetb
gpo7
gpo6
vana
ox
Cell phones, PDAs
Consumer Products, Instrumentation, Automotive
Mechanical Button Replacement
vdig
gnd
pr
d0
cap0
cap1
analog
sensor
interface
clock
generation
RC
SX8639
PWM
LED
controller
gnd
gpo5
d5
d1
cap2
cap3
gpo4
d4
d2
d3
power management
gpo3
gpo2
gnd
gpo1
gpo0
O
RDERING
I
NFORMATION
d3
d2
micro
processor
d7
d4
GPIO
controller
NVM
I2C
cap4
cap5
cap6
RAM
ROM
vdd
cn
cp
Part Number
d1
d0
Temperature
Range
Package
d6
d5
cap7
SX8639I05AULTRT
1
-40°C to +85°C Lead Free MLPQ-UT28
1
bottom plate
intb
sda
3000 Units/reel
scl
HOST
* This device is RoHS/WEEE compliant and Halogen Free
Revision 8_1, December 15
© 2010 Semtech Corp.
1
www.semtech.com
SX8639
Low Power, Capacitive Button and Wheel Touch Controller
(8 sensors) with Enhanced LED Drivers and Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
Table of Contents
DATASHEET
G
ENERAL
D
ESCRIPTION
........................................................................................................................ 1
T
YPICAL
A
PPLICATION CIRCUIT
............................................................................................................ 1
K
EY
P
RODUCT
F
EATURES
..................................................................................................................... 1
A
PPLICATIONS
....................................................................................................................................... 1
O
RDERING
I
NFORMATION
...................................................................................................................... 1
1
1.1
1.2
1.3
1.4
1.5
G
ENERAL
D
ESCRIPTION
............................................................................................................... 4
Pin Diagram
Marking information
Pin Description
Simplified Block Diagram
Acronyms
4
4
5
6
6
2
2.1
2.2
2.3
2.4
E
LECTRICAL
C
HARACTERISTICS
................................................................................................. 7
Absolute Maximum Ratings
Recommended Operating Conditions
Thermal Characteristics
Electrical Specifications
7
7
7
8
3
3.1
3.2
F
UNCTIONAL DESCRIPTION
........................................................................................................ 10
Quickstart Application
Introduction
3.2.1
General
3.2.2
GPIOs
3.2.3
Parameters
3.2.4
Configuration
3.3
Scan Period
3.4
Operation modes
3.5
Sensors on the PCB
3.6
Button and Wheel Information
3.6.1
Button Information
3.6.2
Wheel Information
3.7
Analog Sensing Interface
3.8
Offset Compensation
3.9
Processing
3.10
Configuration
3.11
Power Management
3.12
Clock Circuitry
3.13
I2C interface
3.14
Reset
3.14.1 Power up
3.14.2 RESETB
3.14.3 Software Reset
3.15
Interrupt
3.15.1 Power up
3.15.2 Assertion
3.15.3 Clearing
10
10
10
11
11
11
12
12
14
15
15
15
17
18
19
19
21
21
21
22
22
22
23
24
24
24
24
www.semtech.com
Revision 8_1, December 15
© 2010 Semtech Corp.
2
SX8639
Low Power, Capacitive Button and Wheel Touch Controller
(8 sensors) with Enhanced LED Drivers and Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
3.15.4 Example
3.16
General Purpose Input and Outputs
3.16.1 Introduction and Definitions
3.16.2 GPI
3.16.3 GPP
3.16.4 GPO
3.16.5 Intensity index vs PWM pulse width
3.17
Smart Wake Up
DATASHEET
25
25
25
26
26
27
30
31
4
4.1
4.2
4.3
4.4
4.5
P
IN DESCRIPTIONS
..................................................................................................................... 32
Introduction
ASI pins
Host interface pins
Power management pins
General purpose IO pins
32
32
33
36
37
5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
D
ETAILED
C
ONFIGURATION DESCRIPTIONS
.............................................................................. 38
Introduction
General Parameters
Capacitive Sensors Parameters
Button Parameters
Wheel Parameters
Mapping Parameters
GPIO Parameters
38
41
42
47
51
56
59
6
6.1
6.2
6.3
6.4
6.5
6.6
I2C I
NTERFACE
........................................................................................................................... 63
I2C Write
I2C read
I2C Registers Overview
Status Registers
Control Registers
SPM Gateway Registers
6.6.1
SPM Write Sequence
6.6.2
SPM Read Sequence
6.7
NVM burn
6.8
Monitor Mode
63
64
65
66
69
71
72
73
74
75
7
7.1
7.2
A
PPLICATION
I
NFORMATION
...................................................................................................... 76
Typical Application Schematic
Example of Touch+Proximity Module
7.2.1
Overview
7.2.2
Operation
7.2.3
Performance
7.2.4
Schematics
7.2.5
Layout
76
77
77
77
77
78
79
8
9
9.1
9.2
R
EFERENCES
............................................................................................................................. 80
P
ACKAGING
I
NFORMATION
........................................................................................................ 81
Package Outline Drawing
Land Pattern
81
81
Revision 8_1, December 15
© 2010 Semtech Corp.
3
www.semtech.com
SX8639
Low Power, Capacitive Button and Wheel Touch Controller
(8 sensors) with Enhanced LED Drivers and Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
1 G
ENERAL
D
ESCRIPTION
1.1
Pin Diagram
resetb
gpio7
gpio6
cap0
vana
vdig
gnd
DATASHEET
28
cap1
cap2
cap3
cap4
cap5
cap6
cap7
1
2
3
4
5
27
26
25
24
23
22
SX8639
21
20
gnd
gpio5
gpio4
gpio3
gpio2
gnd
gpio1
Top View
19
18
17
6
7
8
cn
9
cp
10
vdd
bottom ground pad
11
intb
12
scl
13
sda
14
gpio0
16
15
Figure 1
Pinout Diagram
1.2
Marking information
FP29
yyww
xxxxx
R05
yyww = Date Code
xxxxx = Semtech lot number
R05 = Semtech Code
Figure 2
Marking Information
Revision 8_1, December 15
© 2010 Semtech Corp.
4
www.semtech.com
SX8639
Low Power, Capacitive Button and Wheel Touch Controller
(8 sensors) with Enhanced LED Drivers and Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
1.3
Pin Description
Name
CAP1
CAP2
CAP3
CAP4
CAP5
CAP6
CAP7
CN
CP
VDD
INTB
SCL
SDA
GPIO0
GPIO1
GND
GPIO2
GPIO3
GPIO4
GPIO5
GND
GPIO6
GPIO7
VDIG
GND
RESETB
VANA
CAP0
DATASHEET
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Type
Analog
Analog
Analog
Analog
Analog
Analog
Analog
Analog
Analog
Power
Digital Output
Digital Input
Digital Input/Output
Digital Input/Output
Digital Input/Output
Ground
Digital Input/Output
Digital Input/Output
Digital Input/Output
Digital Input/Output
Ground
Digital Input/Output
Digital Input/Output
Analog
Ground
Digital Input
Analog
Analog
Ground
Description
Capacitive Sensor 1
Capacitive Sensor 2
Capacitive Sensor 3
Capacitive Sensor 4
Capacitive Sensor 5
Capacitive Sensor 6
Capacitive Sensor 7
Integration Capacitor, negative terminal (1nF between CN and CP)
Integration Capacitor, positive terminal (1nF between CN and CP)
Main input power supply
Interrupt, active LOW, requires pull up resistor (on host or external)
I2C Clock, requires pull up resistor (on host or external)
I2C Data, requires pull up resistor (on host or external)
General Purpose Input/Output 0
General Purpose Input/Output 1
Ground
General Purpose Input/Output 2
General Purpose Input/Output 3
General Purpose Input/Output 4
General Purpose Input/Output 5
Ground
General Purpose Input/Output 6
General Purpose Input/Output 7
Digital Core Decoupling, connect to a 100nF decoupling capacitor
Ground
Active Low Reset. Connect to VDD if not used.
Analog Core Decoupling, connect to a 100nF decoupling capacitor
Capacitive Sensor 0
Exposed pad connect to ground
bottom plate GND
Table 1
Pin description
Revision 8_1, December 15
© 2010 Semtech Corp.
5
www.semtech.com
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