3 Why Use Interrupts with I²C GPIO Expanders?

The TCA9539A-Q1 open-drain interrupt output is asserted when any input state differs from the corresponding input port register state. This interrupt is used to indicate to the host MCU or SoC that an input state has changed, prompting the controller to initiate a read operation. This allows the host MCU or SoC to operate in an event-driven manner rather than continuously polling GPIO status registers.

This interrupt driven operation reduces I²C bus traffic, lowers software overhead, and can improve system response time in automotive designs.