The MAX9940 signal-line overvoltage protector for lowvoltage digital communication ports provides protection against high-voltage faults and ESD strikes. The MAX9940 is especially useful for sensitive communication protocols such as Maxim 1-Wire that cannot afford standard means of fault protection, such as large series resistors or large line capacitances. The MAX9940 operates from a single supply voltage of +2.2V to +5.5V and consumes only 13A of quiescent supply current. The EXT port is protected up to 28V. The device features a reaction time of 60ns for fast action during fault conditions and operates over the -40C to +125C automotive temperature range.