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PDF SX8644 Data sheet ( Hoja de datos )
| Número de pieza | SX8644 | |
| Descripción | Capacitive Button and Slider Touch Controller | |
| Fabricantes | Semtech | |
| Logotipo |  |
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WIRELESS & SENSING
SX8644
Ultra Low Power, Capacitive Button and Slider
Touch Controller (12 sensors) with Enhanced LED Drivers
DATASHEET
GENERAL DESCRIPTION
The SX8644 is an ultra low power, fully integrated
12-channel solution for capacitive touch-buttons and
slider applications. Unlike many capacitive touch
solutions, the SX8644 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 SX8644 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 SX8644 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 SX8644 supports the 400 kHz I²C serial bus
data protocol and includes a field programmable
slave address. The SX8644 is available in a tiny
MLPQ 5mm x 5mm package. The small footprint
make it an ideal solution for portable, battery
powered applications where power and density are
at a premium.
KEY PRODUCT FEATURES
Complete Twelve Sensors Capacitive Touch Controller for
Buttons and Slider
Pre-configured for 6 Buttons and a Slider
8 LED Drivers with Individual Intensity, Fading Control
and Autolight Mode
256 steps PWM Linear and Logarithmic control
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)
220uA (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
TYPICAL APPLICATION CIRCUIT
APPLICATIONS
Notebook/Netbook/Portable/Handheld computers
Cell phones, PDAs
Consumer Products, Instrumentation, Automotive
Mechanical Button Replacement
ORDERING INFORMATION
Part Number
Temperature
Range
Package
SX8644I05AWLTRT1 -40°C to +85°C Lead Free MLPQ-W32
1 3000 Units/reel
* This device is RoHS/WEEE compliant and Halogen Free
Revision 7_6, October 12
© 2012 Semtech Corp.
1
www.semtech.com
1 page  
WIRELESS & SENSING
SX8644
Ultra Low Power, Capacitive Button and Slider
Touch Controller (12 sensors) with Enhanced LED Drivers
DATASHEET
1.3 Pin Description
Number Name
1 CAP2
2 CAP3
3 CAP4
4 CAP5
5 CAP6
6 CAP7
7 CAP8
8 CAP9
9 CAP10
10 CAP11
11 CN
12 CP
13 VDD
14 INTB
15 SCL
16 SDA
17 GPIO0
18 GPIO1
19 GND
20 GPIO2
21 GPIO3
22 GPIO4
23 GPIO5
24 GND
25 GPIO6
26 GPIO7
27 VDIG
28 GND
29 RESETB
30 VANA
31 CAP0
32 CAP1
bottom plate GND
Type
Description
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
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
Table 1 Pin description
Revision 7_6, October 12
© 2012 Semtech Corp.
5
www.semtech.com
5 Page 
WIRELESS & SENSING
SX8644
Ultra Low Power, Capacitive Button and Slider
Touch Controller (12 sensors) with Enhanced LED Drivers
DATASHEET
The information between SX8644 and the user’s host is passed through the I2C interface with an additional
interrupt signal indicating that the SX8644 has new information. For buttons this information is simply touched or
released.
3.2.2 GPIOs
A second path of feedback to the user is using General Purpose Input Output (GPIO) pins. The SX8644 offers
eight individual configurable GPIO pins. The GPIO can e.g. be set as a LED driver which slowly fade-in when a
finger touches a button and slowly fade-out when the button is released. Fading intensity variations can be
logarithmic or linear. Interval speed and initial and final light intensity can be selected by the user. The fading is
done using a 256 steps PWM. The SX8644 has eight individual PWM generators, one for each GPIO pin.
The LED fading can be initiated automatically by the SX8644 by setting the SX8644 Autolight feature. A simple
touch on a sensor and the corresponding LED will fade-in without any host interaction over the I2C.
In case the Autolight feature is disabled then the host will decide to start a LED fading-in period, simply by setting
the GP0 pin to ‘high’ using one I2C command. The SX8644 will then slowly fade-in the LED using the PWM
autonomously.
In case the host needs to have full control of the LED intensity then the host can set the GPIO in GPP mode. The
host is then able to set the PWM pulse width freely at the expense of an increased I2C occupation.
The GPIOs can be set further in the digital standard Input mode (GPI).
3.2.3 Parameters
The SX8644 has many low level built-in, fixed algorithms and procedures. To allow a lot of freedom for the user
and adapt the SX8644 for different applications these algorithms and procedures can be configured with a large
set of parameters which will be described in the following sections. Examples of parameters are which sensors
are buttons or which sensors are parts of a slider, which GPIO is used for outputs or LEDs and which GPIO is
mapped to which button.
Sensitivity and detection thresholds of the sensors are part of these parameters. Assuming that overlay material
and sensors areas are identical then the sensitivities and thresholds will be the same for each sensor. In case
sensors are not of the same size then sensitivities or thresholds might be chosen individually per sensor.
So a smaller size sensor can have a larger sensitivity while a big size sensor may have the lower sensitivity.
3.2.4 Configuration
During a development phase the parameters can be determined and fine tuned by the users and downloaded
over the I2C in a dynamic way. The parameter set can be downloaded over the I2C by the host each time the
SX8644 boots up. This allows a flexible way of setting the parameters at the expense of I2C occupation.
In case the parameters are frozen they can be programmed in Multiple Time Programmable (MTP) Non Volatile
Memory (NVM) on the SX8644. The programming needs to be done once (over the I2C). The SX8644 will then
boot up from the NVM and additional parameters from the host are not required anymore.
In case the host desires to overwrite the boot-up NVM parameters (partly or even complete) this can be done by
additional I2C communications.
Revision 7_6, October 12
© 2012 Semtech Corp.
11
www.semtech.com
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet SX8644.PDF ] | |
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