The MAX7321 2-wire serial-interfaced peripheral features eight open-drain I/O ports with selectable internal pullups and transition detection. Any port may be used as a logic input or an open-drain output. Ports are overvoltage protected to +6V independent of supply voltage. All I/O ports configured as inputs are continuously monitored for state changes (transition detection). State changes are indicated by the open-drain, +6V tolerant INT output. The interrupt is latched, allowing detection of transient changes. When the MAX7321 is subsequently accessed through the serial interface, any pending interrupt is cleared.