8-bit I²C I/O expander with POR and interrupt
The MAX7321AEE+ is an 8-bit I/O expander from Analog Devices that communicates over an I²C bus at up to 400 kHz. Each of the eight I/O ports can be configured as an input or output, with outputs selectable as open-drain or push-pull — a feature that lets the same part drive LEDs directly (push-pull) or interface with wired-OR interrupt lines (open-drain). An integrated power-on reset (POR) circuit ensures the outputs come up in a known high-impedance state, preventing unintended glitches on the load during power-up. The interrupt output (INT) signals the host when an input changes state, so the host does not need to poll the I²C bus continuously — useful in battery-powered designs where every microamp counts.
Each I/O can source or sink 20 mA, enough to drive a standard LED or a low-power optocoupler directly. The open-drain configuration allows multiple expanders to share an interrupt line without contention.
Available in a 16-pin SSOP (3.90 mm body width) and also listed with a 16-QSOP supplier package — both are surface-mount, fine-pitch packages suited for compact PCB layouts. The tube packaging is standard for engineering samples and low-volume production runs.