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 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
Figure 2 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.