The MAX4505 is a single signal-line protector featuring a fault-protected input and Rail-to-Rail signal handling capability. The input is protected from overvoltage faults up to 36V with power on or 40V with power off. During a fault condition, the input terminal becomes an open circuit and only nanoamperes of leakage current flow from the source, while the switch output (AOUT) furnishes typically 19mA from the appropriate polarity supply to the load. This ensures an unambiguous rail-to-rail output when a fault begins and ends.