The RDYN is calculated by taking the difference of two clamping voltages generated by two different current levels and using the relationship of R equals V divided by I. As shown here, the two current levels are 1A and 2A so when the clamping voltage is subtracted at these two levels and divided by two minus one, or simply one, it makes the calculation very simple. This parameter is by far the best way to compare protection devices between different manufacturers.