The ESD321 is a diode type TVS which is used to provide a path to ground for dissipating ESD events on high-speed signal lines between a human interface connector and a system. As the current from ESD passes through the TVS, only a small voltage drop is present across the diode. This is the voltage presented to the protected IC. The low R_DYN of the triggered TVS holds this voltage, V_CLAMP, to a safe level for the protected IC.