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December 8, 2019
Question

Used eDesignSuite to design an isolated AC to DC Flyback converter circuit for wide voltage AC input, and 5V, 0.8A DC output.

  • December 8, 2019
  • 0 replies
  • 574 views

The eDesignSuite result and my schematic are attached.

A PCB was manufactured as per the eDesignSuite BOM and design guidelines.

I connected mains to the circuit without SJ4 being bridged. Rin immediately blew. The design BOM specified a 7.5Ω , 2W resistor. Guessing that inrush current may be larger due to my using 4.7uF instead of 4.3uF at CIN1 and CIN2 , I replace the resistor with a 6.8Ω , 4W, and this worked.

The no-load voltage measured at TP8 was 5.8V.

When I connected a 47Ω , 5W resistor between TP8 and GND, the voltage at TP8 dropped to about 0.9V.

Any suggestions regarding my approach towards finding out what I might do to find a possible problem will be greatly appreciated.

Thank you.

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