CAP1028
8 Channel Capacitive Touch
Sensor with 2 LED Drivers
PRODUCT FEATURES
General Description
The CAP1028 is a multiple channel Capacitive Touch
sensor with multiple power LED drivers. It contains eight
(8) individual Capacitive Touch sensor inputs with
programmable sensitivity for use in touch sensor
applications. Each sensor automatically recalibrates to
compensate for gradual environmental changes.
The CAP1028 also contains two (2) LED drivers that
offer full-on / off, variable rate blinking, dimness controls,
and breathing. Each of the LED drivers may be linked to
one of the sensors to be actuated when a touch is
detected. As well, each LED driver may be individually
controlled via a host controller.
The CAP1028 offers multiple power states operating at
low quiescent currents.
During the Standby mode of operation, one or more
Capacitive Touch Sensors are active and all LEDs may
be used. If a touch is detected, then it will wake the
system using the WAKE/SPI_MOSI pin.
The Deep Sleep mode of operation is the lowest power
state available drawing 3uA of current. During this
mode, no sensors are activethough all LEDs may be
u s e d . D r i v i n g t h e WA K E / S P I _ M O S I p i n o r
communications will wake the device.
Datasheet
Applications
Desktop and Notebook PC’s
LCD Monitors
Printers
Appliances
Features
Eight (8) Capacitive Touch Sensor Inputs
— Programmable sensitivity
— Automatic recalibration
— Individual thresholds for each button
Flexible Capacitive Touch Sense algorithm
Multiple Communication interfaces
—
—
—
—
SMBus / I
2
C compliant interface
SMSC BC-Link interface
SPI communications
Pin selectable communications protocol and multiple
slave addresses (SMBus / I
2
C only)
Low Power operation
— 3uA quiescent current in Deep Sleep
— Samples one or more channels in Standby
Two (2) LED Driver Outputs
— Open Drain or Push-Pull
— Programmable blink, breathe, and dimness controls
— Can be linked to Capacitive Touch Sensors
Dedicated Wake output flags touches in low power
mode
System RESET pin
Available in 20-pin 4mm x 4mm RoHS compliant
QFN package
Block Diagram
LED1
LED2
RESET
VDD GND
WAKE / SPI_MOSI
SPI_CS#
SMBus
/ BC-
Link /
SPI
Slave
Protocol
SMCLK/ BC_CLK /
SPI_CLK
SMDATA / BC_DATA/
SPI_MSIO / SPI_MISO
ALERT# / BC_IRQ#
ADDR_COMM
LED Driver, Breathe,
and Dimness control
Capacitive Sensing Algorithm
CS1 CS2
2
CS3 CS4 CS5 CS6 CS7 CS8
Note:
I C is a trademark of NXP semiconductor. BC-Link is a trademark of SMSC.
SMSC CAP1028
DATASHEET
Revision 1.1 (08-05-09)
SMSC [ SMSC CORPORATION ]
