8-bit I2C GPIO expander for board-level I/O scaling
The NXP PCAL9554BPWJ is an 8-bit general-purpose I/O expander from the Agile series, communicating over an I²C or SMBus interface at up to 400 kHz. It provides eight configurable I/O pins that can be set as open-drain or push-pull outputs, with a power-on reset (POR) ensuring a known startup state. The interrupt output signals the host when an input changes, eliminating constant polling. Typical applications include server motherboards, industrial control panels, and telecom line cards where a microcontroller lacks enough GPIO pins.
Supply range and logic-level compatibility
No separate level shifter is needed when the host controller runs at a different voltage — the expander's I/O pins track VDD.
Output drive and pull-up planning
Each I/O can source 10 mA or sink 25 mA.
Surface-mount assembly is standard; no special handling beyond normal SMT reflow.
NXP lists the PCAL9554BPWJ as Active and ROHS3 compliant.