Primary resistor feedback is used only with the PWM control devices. This includes both the DPASwitch and the TOPSwitch families of products. It is the least expensive, but it has the lowest absolute accuracy and regulation of the feedback circuits for the TOPSwitch family. Primary resistor feedback is only suitable for low power and higher output voltages (VO > 5 V).
When primary side resistor 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.