The PCA967x family of devices are Fast-Mode Plus General Purpose I/O Expanders. In an application, the user may connect an LED from an I/O, via a current-limiting resistor, to VDD. By sending an I2C command to the device to drive the I/O low, the user may turn the LED light on. In the same token, by sending an I2C command to the device to drive the I/O high, the user may turn the LED light off. In this application, the GPIO may be used as an LED Switch. A drawback with this implementation is that every time the LED needs to be switched on or off, a command needs to be sent to the device. This can result in high bus traffic if the LED’s are switched on-and-off frequently.