44.6 Handling VPEAK Variations
If the peak amplitude of the external voltage is expected to
            vary, the series resistor must be selected to keep the ZCD current source and to sink
            below the design maximum range specified by ZC02, and above a reasonable minimum range,
            depending on the application. The compensating pull-up for this series resistance can be
            determined with the equations shown in Equation 44-5 because the pull-up value is independent from the peak voltage.
      Tip: It is recommended that the
               maximum peak voltage be no more than six times the minimum peak voltage.
