The PCA9535PW,112 is a 16-bit CMOS I²C-bus and SMBus, low power I/O Port with interrupt provide 16-bit of general purpose parallel input/output (GPIO) expansion for I²C-bus/SMBus applications and was developed to enhance the semiconductors family of I²C-bus I/O expanders. The improvements include higher drive capability, 5V I/O tolerance, lower supply current, individual I/O configuration and smaller packaging. I/O expanders provide a simple solution when additional I/O is needed for ACPI power switches, sensors, push buttons, LEDs and fans. The open-drain interrupt output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system master that an input state has changed. The power-on reset sets the registers to their default values and initializes the device state machine.