Active 16-bit I/O expander for I²C and SMBus
The PCA9555DBQR: The 16 I/O channels are arranged as two 8-bit ports, each configurable as input or output with push-pull drive. An interrupt output signals the host when an input state changes, saving the MCU from polling the bus.
Supply voltage and temperature envelope
Each I/O pin can source 10 mA or sink 25 mA, enough to drive LEDs directly or interface with logic-level loads without an external buffer. The total current per port is limited by the package thermal constraints, but for typical GPIO expansion this is rarely the bottleneck.
24-SSOP package and rework considerations
The body is small enough to fit tight layouts but large enough that the leads are visible for inspection. Available in Tape & Reel (TR) and Cut Tape (CT) options, so it suits both volume pick-and-place and prototype runs.