預穩式：適用於低壓、反應快、低漣波

The pre-regulator functions in a similar fashion to provide line and load regulation.
The series pass stage, in addition to giving the CD Series its tight regulation characteristic , reacts rapidly to line and load changes to Produce a transient response characteristic similar to the linear series pass types.

With a relatively constant voltage across the series pass stage more efficient use is made of series transistor capacity, and hence ,the pre-regulator approach yields a four or five-to one reduction in the number of series pass transistors.