The dynamic resistance is the most critical parameter for describing the protection offered by an ESD device. Designated as RDYN, the dynamic resistance is the impedance exhibited by the protection component when shunting an ESD pulse or surge event to GND. The ideal protection device would have a 0 Ohm impedance so that all of the ESD current would be absorbed in the component sparing the IC. However, in reality there is a sharing of current between the protection component and the IC so the dynamic resistance needs to be as low as possible to limit the energy seen by the IC. In short, the lower the dynamic resistance and the clamping voltage the more likely it is that the IC will survive an ESD event.