The MAX4631/MAX4632/MAX4633 high-voltage, dual analog switches are pin compatible with the industry-standard DG401/DG403/DG405. They upgrade the existing devices with fault-protected inputs and Rail-to-Rail signal handling capabilities. The MAX4631/MAX4632/MAX4633's normally open (NO) and normally closed (NC) terminals are protected from overvoltage faults up to 36V during power-up or power-down. During a fault condition, these terminals become open circuit and only nanoamperes of leakage current flow from the source, yet the switch output (COM_) continues to furnish up to 18mA of the appropriate polarity supply voltage to the load. This ensures unambiguous rail-to-rail outputs when a fault begins and ends. On-resistance is 85 (max) at +25C and is matched between switches to 6 (max). Off-leakage current is only 0.5nA at +25C and 5nA at +85C.