VRM is the maximal operating voltage of the protection to ensure a good transparency of the application voltage signal in the normal operation. The VRM of the ESD protection must be higher than the normal signal voltage amplitude. If the signal is negative and positive, the protection must be bi-directional to avoid rectifier phenomenon. If the signal to be protected is only positive, an unidirectional protection is preferred. Along with the VRM voltage there is also the protection current leakage parameter called IRM. A too high leakage current can affect the system overall consumption but it can also change a data line voltage. Usually, the leakage current is below 1 μA at VRM (ESDZV5 has IRM e.g. at 100 nA maximum).