Primary zener feedback is used only with the PWM control devices. This includes both the DPASwitch and the TOPSwitch family of products. Primary zener feedback is low cost and has good line and load regulation. Careful selection of bias winding voltage and zener selection will help provide the best regulation using primary side feedback methods.
When primary side zener feedback has been chosen, the Feedback Components dialog will display all the feedback circuit values. Each component can be changed, and these changes will be reflected in the schematic and BOM.