The PI4IOE5V9554 and PI4IOE5V9554A provide 8 bits of general purpose parallel input/output (GPIO) expansion for I 2 C-bus/SMBus applications. The device includes features such as higher driving capability, 5V tolerance, lower power supply, individual I/O configuration, and smaller packaging. It provides a simple solution when additional I/O is required for ACPI power switches, sensors, push buttons, LEDs, fans, etc.

The PI4IOE5V9554/PI4IOE5V9554A consists of an 8-bit register to configure the I/Os as either inputs or outputs and an 8-bit polarity register to change the polarity of the input port register data. The data for each input or output is kept in the corresponding input port or output port register. All registers can be read by the system master. The PI4IOE5V9554/PI4IOE5V9554A open-drain interrupt output is activated and indicates to the system when any input state has changed.

The power-on reset sets the registers to their default values and initializes the device state machine. Three hardware pins (A0, A1, A2) vary the fixed I2 C-bus address and allow up to eight devices to share the same I2 Cbus/SMBus. The PI4IOE5V9554A is identical to the PI4IOE5V9554 except the fixed I2 C-bus address is different, allowing up to sixteen of these devices (eight of each) on the same I2 C-bus/SMBus.