The MAX1608/MAX1609 provide remote input/output (I/O) expansion through an SMBus™ 2-wire serial interface. Each device has eight high-voltage open-drain outputs that double as TTL-level logic inputs, providing continuous bidirectional capabilities. The open-drain outputs tailor the MAX1608/MAX1609 for use in load-switching and other level-shifting applications as well as general-purpose I/O applications.Two complete sets of registers allow the device and its outputs to be toggled between two states using the active-low SMBSUS input, without the inherent latency of reprogramming outputs over the serial bus. The eight I/O lines are continuously monitored and can be used as inputs. Each line can generate asynchronous maskable interrupts on the falling edge, the rising edge, or both edges.For load-switching applications, the MAX1608 is designed to drive N-channel MOSFETs, and its outputs are low upon power-up; the MAX1609 is designed to drive P-channel MOSFETs, and its I/Os are high impedance upon power-up. Other features of both devices include thermal-overload and output-overcurrent protection, ultra-low supply current, and a wide +2.7V to +5.5V supply range. The MAX1608/MAX1609 are available in space-saving 16-pin QSOP packages.ApplicationsIndustrial EquipmentNotebook and Desktop ComputersNotebook Docking StationsParallel I/O ExpansionPower-Plane SwitchingServers and Workstations