Dual Regulated Output

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I am designing a dual output constant voltage power supply. Below are my specs :-

  • 17V@1A
  • 3.3V@1A
  • Isolated output


I used PI's expert solution get design reference. Attached is the schematic.


Now only 3.3V is regulated, but I want both output to be regulated. I can't find any option in PI's expert to change the output type. Kindly help





Powe Supply Schematic200.02 KB

Dear Anuj,


For multiple-output power supplies, using weighted feedback may be appropriate.  Please see application note AN-22 (page 12) using the link provided below:




Note that when weighted feedback is used, regulation of the main regulated output is traded off, achieving improvement in regulation of the additional outputs to improve the overall performance.


To use two output voltages for feedback correction in PIExpert, please select feedback, then select components and in the popup select dual output control.  Regulation of multiple outputs depends on the transformer construction, values of output capacitors, and rectifier diode characteristics.  We suggest you verify cross regulation of the power supply at nominal as well as the lowest and highest input voltage to determine the minimum load needed.  Regulation also greatly depends on the distribution of power among the individual outputs and the main regulated output.