The PI4IOE5V9535 is a 24-pin device that provides 16 bits of General Purpose parallel Input/Output (GPIO) expansion for I2 C-bus/SMBus applications It includes the 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 needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc.

The PI4IOE5V9535 consists of two 8-bit Configuration (Input or Output selection), Input, Output and Polarity Inversion (active HIGH or active LOW operation) registers. The system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding Input port or Output port register. The polarity of the read register can be inverted with the Polarity Inversion register. All registers can be read by the system master.

The PI4IOE5V9535 is identical to the PI4IOE5V9555 except for the removal of the internal I/O pull-up resistor which greatly reduces power consumption when the I/Os are held LOW. The PI4IOE5V9535 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.

Three hardware pins (A0, A1, A2) vary the fixed I2C-bus address and allow up to eight devices to share the same I2Cbus/SMBus. The fixed I2C-bus address of the PI4IOE5V9535 are the same as the PI4IOE5V9535 allowing up to eight of these devices in any combination to share the same I2C-bus/SMBus.