I²C I/O expander for GPIO-limited designs
The PCA9534DW from Texas Instruments is an 8-bit I²C and SMBus I/O expander that adds eight general-purpose I/O pins to a microcontroller or processor with a limited GPIO count. It communicates over a 400 kHz I²C bus, freeing up processor pins for other functions. Each I/O pin can be individually configured as input or output, with push-pull outputs capable of sourcing 10 mA and sinking 25 mA. An interrupt output (INT) signals the host when an input changes state, reducing polling overhead.
Package and board integration
Housed in a 16-SOIC package with a 7.50 mm body width (0.295-inch), the PCA9534DW fits standard SOIC-16 footprints. The wide body provides adequate clearance for manual probing and rework, and the surface-mount package supports automated assembly without special handling. The tube packaging is typical for prototype and low-volume builds; for reel packaging check the alternate order code PCA9534DWR.