The MAX7300 compact, serial-interfaced, I/O expansion peripheral provides microprocessors with up to 28 ports. Each port is individually user configurable to either a logic input or logic output. Each port can be configured as either a push-pull logic output capable of sinking 10mA and sourcing 4.5mA, or a Schmitt logic input with optional internal pullup. Seven ports feature configurable transition detection logic, which generates an interrupt upon change of port logic level. The MAX7300 is controlled through an I2CTM-compatible 2-wire serial interface, and uses four-level logic to allow 16 I2C addresses from only two select pins. The MAX7300AAX and MAX7300AGL have 28 ports and are available in 36-pin SSOP and 40-pin QFN packages, respectively. The MAX7300AAI and MAX7300ANI have 20 ports and are available in 28-pin SSOP and 28pin DIP packages, respectively.