The NXP PCA9555DB is a 16-bit I²C/SMBus GPIO expander in a 24-SSOP package, designed to add digital I/O to systems where the host controller's port count is exhausted. It communicates over a 400 kHz I²C bus and provides 16 push-pull outputs, each capable of sourcing 10 mA or sinking 25 mA. With an interrupt output and a power-on reset (POR) feature, it suits industrial control panels, telecom line cards, and embedded systems that need extra I/O without a larger MCU.
The PCA9555DB is listed as obsolete. NXP no longer manufactures this specific variant, so new production buys are not available through the factory channel.
Ratings that decide the fit
The 16 I/O count is the primary selection parameter — it determines whether this part covers your expansion needs. The 400 kHz I²C clock is standard for most bus architectures; if your system runs a slower or faster I²C bus, confirm the master can match this speed. The 10 mA source / 25 mA sink per output is enough to drive LEDs, small relays, or logic inputs directly; for higher loads, buffer the outputs.
The 24-SSOP (0.209", 5.30 mm width) is a surface-mount package with a 0.65 mm pitch — standard for automated assembly. The supplier device package is 24-SSOP. The part ships in Tube form.