8-bit I²C GPIO expander in a wide-body SOIC
It gives a system with limited MCU pins eight additional GPIOs, each configurable as input or push-pull output, with a dedicated interrupt output that flags any input change. The part includes a Power-On Reset (POR) circuit that initializes the I/O ports to inputs, so no external reset supervisor is needed on the expander rail.
Output drive and I/O characteristics
The push-pull output structure means no external pull-up resistor is needed when the pin is configured as an output — unlike open-drain expanders that require a pull-up for high-level drive. The interrupt output (active-low, open-drain) asserts when any input pin changes state from the last I²C read, which lets the host MCU sleep until a GPIO event occurs rather than polling the expander. This is useful for keypad scanning, sensor monitoring, or any application where the MCU needs to minimize active time.
Package and footprint note
It is a surface-mount package suitable for reflow soldering. The Tube shipping medium is common for prototyping and low-volume production; for higher volumes the part is also available in Tape & Reel (check the full ordering options under base number PCA9554).