SX8662
Capacitive Button Matrix (up to 36) Controller
with Individual LED Drivers and Buzzer Output
ADVANCED COMMUNICATIONS & SENSING
G
ENERAL
D
ESCRIPTION
The SX8662 is an ultra low power, fully integrated
12-channel solution for capacitive touch-button
matrix applications (up to 36 keys). Unlike many
capacitive touch solutions, the SX8662 features
dedicated capacitive sense inputs (that requires no
external components) in addition to 8 general
purpose I/O ports (GPIO) which can be used to drive
up to 36 matrix LEDs (i.e. one per key). Each of the
on-chip GPIO/LED driver is equipped with
independent PWM source for enhanced visual effect
such as dimming, and breathing.
The SX8662 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 SX8662 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 SX8662 supports the 400 kHz I²C serial bus
data protocol and includes a field programmable
slave address. The tiny 5mm x 5mm footprint makes
it an ideal solution for portable, battery powered
applications where power and density are at a
premium.
K
EY
P
RODUCT
F
EATURES
Complete Capacitive Touch-Button Solution
o
Up to 36 Matrix Buttons
o
Up to 36 LEDs Control for individual Visual Feedback
with Auto Lightening
o
Configurable Single or Continuous Fading Mode
o
256 steps PWM Linear and Logarithmic control
High Resolution Capacitive Sensing
o
Up to 100pF of Offset Cap. Compensation at Full
Sensitivity
o
Capable of Sensing up thru 5mm thick Overlay Materials
Support of buzzer for audible feedback
User-selectable Button Reporting Configuration
Extremely Low Power
o
8uA (typ) in Sleep Mode
o
100uA (typ) in Doze Mode (195ms)
o
460uA (typ) in Active Mode (30ms)
Programmable Scanning Period from 15ms to several seconds
Auto Offset Compensation
o
Eliminates false triggers due to environmental factors
(temperature, humidity)
o
Initiated on power-up and configurable intervals
Multi-Time In-Field Programmable Firmware Parameters
for Ultimate Flexibility
o
On-chip user programmable memory for fast, self
contained start-up
No External Components per Sensor Input
Internal Clock Requires No External Components
Differential Sensor Sampling for Reduced EMI
Optional 400 KHz I²C Interface with Programmable Address
-40° to +85° Operation
C
C
A
PPLICATIONS
T
YPICAL
A
PPLICATION CIRCUIT
cap0
resetb
Home Automation
White Goods
buzzer
gpio7
vana
36 Capacitive Matrix Buttons
cap0
cap1
cap10
cap2
cap3
cap8
Printers
Notebook/Netbook/Portable/Handheld computers
Consumer Products, Instrumentation, Automotive
Mechanical Button Replacement
vdig
gnd
cap1
cap2
analog sensor
interface
clock
generation
RC
SX8662
PWM LED
controller
gnd
cap3
cap11
cap4
cap9
gpio6
power management
gpio4
cap7
cap6
micro processor
GPIO controller
gpio3
36 Matrix LEDs
cap5
gpio5
cap6
O
RDERING
I
NFORMATION
Part Number
1
cap7
gpio2
RAM
NVM
cap8
cap5
cap9
gpio1
gpio0
ROM
I2C
bottom plate
Temperature
Range
Package
cap4
cap11
vdd
sda
cn
cp
intb
scl
cap10
SX8662I08AWLTRT -40° to +85° Lead Free MLPQ-W32
C
C
HOST
3000 Units/reel
* This device is RoHS/WEEE compliant and Halogen Free
1
Rev5 4 August 2011
th
© 2011 Semtech Corp.
1
www.semtech.com
SX8662
Capacitive Button Matrix (up to 36) Controller
with Individual LED Drivers and Buzzer Output
ADVANCED COMMUNICATIONS & SENSING
Table of Contents
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
F
UNCTIONAL DESCRIPTION
........................................................................................................ 10
10
10
10
10
10
11
12
12
12
12
14
14
16
17
17
19
19
19
20
20
20
20
21
21
21
22
www.semtech.com
Introduction
3.1.1
General
3.1.2
Parameters
3.1.3
Configuration
3.2
Scan Period
3.3
Operation modes
3.4
Sensors on the PCB
3.4.1
Matrix Keys/Buttons (MK)
3.4.2
Priority Key/Button (PK)
3.4.3
Schematics Requirements
3.5
Button Information (MK and PK)
3.6
Analog Sensing Interface
3.7
Offset Compensation
3.8
Processing
3.9
Configuration
3.10
Power Management
3.11
Clock Circuitry
3.12
I2C interface
3.13
Interrupt
3.13.1 Power up
3.13.2 Assertion
3.13.3 Clearing
3.13.4 Example
3.14
Reset
3.14.1 Power up
3.14.2 RESETB
th
Rev5 4 August 2011
© 2011 Semtech Corp.
2
SX8662
Capacitive Button Matrix (up to 36) Controller
with Individual LED Drivers and Buzzer Output
ADVANCED COMMUNICATIONS & SENSING
3.14.3 Software Reset
3.15
General Purpose Input and Outputs
3.15.1 GPO
3.15.2 Fading Modes
3.15.3 Intensity index vs PWM pulse width
3.15.4 Tri-State Multiplexing (TSM)
22
23
23
25
26
27
4
4.1
4.2
4.3
4.4
4.5
P
IN DESCRIPTIONS
..................................................................................................................... 28
Introduction
ASI pins
Host interface pins
Power management pins
General purpose IO pins
28
28
29
32
33
5
5.1
5.2
5.3
5.4
5.5
5.6
D
ETAILED
C
ONFIGURATION DESCRIPTIONS
.............................................................................. 34
Introduction
General Parameters
Capacitive Sensors Parameters
Buttons (MK and PK) Parameters
Buzzer Parameters
GPIO Parameters
34
37
38
40
43
44
6
6.1
6.2
6.3
6.4
6.5
6.6
I2C I
NTERFACE
........................................................................................................................... 47
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
47
48
49
50
52
53
54
55
56
7
8
9
9.1
9.2
A
PPLICATION
I
NFORMATION
...................................................................................................... 57
R
EFERENCES
............................................................................................................................. 58
P
ACKAGING
I
NFORMATION
........................................................................................................ 59
Package Outline Drawing
Land Pattern
59
59
Rev5 4 August 2011
th
© 2011 Semtech Corp.
3
www.semtech.com
SX8662
Capacitive Button Matrix (up to 36) Controller
with Individual LED Drivers and Buzzer Output
ADVANCED COMMUNICATIONS & SENSING
1.3
Pin Description
Name
CAP2
CAP3
CAP4
CAP5
CAP6
CAP7
CAP8
CAP9
CAP10
CAP11
CN
CP
VDD
INTB
SCL
SDA
GPIO0
GPIO1
GND
GPIO2
GPIO3
GPIO4
GPIO5
GND
GPIO6
GPIO7
VDIG
GND
RESETB
VANA
CAP0
CAP1
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
29
30
31
32
Type
Analog
Analog
Analog
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
Analog
Ground
Description
Capacitive Sensor 2
Capacitive Sensor 3
Capacitive Sensor 4
Capacitive Sensor 5
Capacitive Sensor 6
Capacitive Sensor 7
Capacitive Sensor 8
Capacitive Sensor 9
Capacitive Sensor 10
Capacitive Sensor 11
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
Capacitive Sensor 1
Exposed pad connect to ground
Bottom Plate GND
Table 1
Pin description
Rev5 4 August 2011
th
© 2011 Semtech Corp.
5
www.semtech.com
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