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UCC28911: Wide VIn (20V-400V) isolated DC/DC converter

Part Number: UCC28911
Other Parts Discussed in Thread: PMP30070, UCC28700

Hi There,

My aerospace customer is looking for a solution for wide input voltage DC/DC conversion.

Here are the specifications in the nutshell:

  • Maximum input voltage:  440 Vdc
  • Minimum input voltage:  ~20 Vdc – 100 Vdc
  • Isolated primary / secondary
  • Output voltage: 15 Vdc
  • Output current: 400 mA
  • Prefer integrated switch, but can accept discrete switch
  • Topology: probably flyback, but others are acceptable

I have suggested UCC28911 and PMP30070 as an example of the implementation.

The question is, how do I modify the PMP30070 to extend the input voltage range to 20V to 440V?

If I am way off base, please suggest a different solution.



  • Hello Tom,

    The UCC28911 has an internal startup circuit that needs to be greater than 30V to operate correctly.  So this device may not be the correct one for your application.

    I believe the input range might be too wide for this application.   Generally it recommended the input range be less than 9 to 1.   However, I found a reference design using the UCC28700 that is designed for 25V to 520V DC input with a 28V output so it might be possible.   The following link will get to this reference design. input range flyback&tisearch=Search-EN-Everything

    If you were to use the UCC28700 reference design the transformer turns ratios would need to be adjusted to support 15V.  The data sheet give calculations for how to set the transformer turns ratio based on volt second balance at the minimum input voltage.