MY DESIGNED 18V SMPS GIVES ME 37V OUTPUT

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I WAS DESIGNED 18V/2.5A OUTPUT SMPS BY USING PI-EXPERT AND USED DEVICE IS TOP248YN.I WAS USED ETD29 INSTEAD OF EF25 TRANSFORMER.PLEASE GUIDE ME FOR SOLVING MY PROBLEM

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18V/2.5A279 KB

Hi Pareshj,

Thank you very much for choosing Power Integrations.

May I know what is the end application of your power supply?

Is there a particular reason why you used ETD29 instead of the suggested EF25? Possible cause of the increased output voltage is the load. Will the output voltage go down to 18V if you apply a load to the output? Try connecting a 100kohm preload resistor to the output and check if the output voltage will stay at 18V.

I would also like to note that TOP248 is one of the older part for Topswitch. You might want to try using TopswitchJX.