8 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
Chapter 4 General Description
The CAP1128 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 input automatically recalibrates to compensate for gradual
environmental changes.
The CAP1128 also contains two (2) low side (or push-pull) 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
sensor inputs to be actuated when a touch is detected. As well, each LED driver may be individually
controlled via a host controller.
Finally, the device contains a dedicated RESET pin to act as a soft reset by the system.
The CAP1128 offers multiple power states. It operates at the lowest quiescent current during its Deep
Sleep state. In the low power Standby state, it can monitor one or more channels and respond to
communications normally. The device contains a wake pin (WAKE/SPI_MOSI) output to wake the
system when a touch is detected in Standby and to wake the device from Deep Sleep.
The device communicates with a host controller using the SPI bus, SMSC BC-Link bus, or via SMBus
/ I2C. The host controller may poll the device for updated information at any time or it may configure
the device to flag an interrupt whenever a touch is detected on any sensor pad.
A typical system diagram is shown in Figure 4.1.
Revision 1.32 (01-05-12)
SMSC CAP1128
DATA3S0HEET
SMSC [ SMSC CORPORATION ]
