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UCC28700: UCC28713/UCC28700

Guru 13485 points
Part Number: UCC28700
Other Parts Discussed in Thread: UCC28713, , PMP10200

I'm using TI WEBENCH for a DC/DC converter based on UCC28713.


The WEBENCH is limited to minimum Vin of 85Vrms / 90Vdc – is it limitation of the controller?

I do see a reference design w/ UCC28700 for ultra wide range of 25 to 525Vdc. (PMP10200)

(not supported in WEBENCH either for lower Vin than 85V)


The P/S we need:

  Topology:     DC/DC, Flyback, PSR (Primary Side Regulation)

  Input:                42V to 420Vdc

  Output 1:     24 to 28Vdc, 0.4A

  Output 2:     6.5 to 8Vdc, 0.8A, this output is not mandatory

  Sw. Fr:               40 to 120 kHz

  Eff.:         75% min at 60% load

  Transformer:  should be of the shelf, similar to WE 750811647, or WE 750315315

  • The WEBENCH design tool is designed around the typical application parameters for an AC input. However, the devices are guaranteed to work as long as the input is higher than the UVLO turn on point such as 23V for both the UCC28713 and UCC28700.

    The UCC28700 will work with the wide input range you have specified. There may be limitations attaining full power output at lower inputs. Note in the reference design that using a 25VDC input the output power cuts off at 13W.

    Multiple outputs are possible, but as with any primary side regulation, cross regulation is less than ideal, but your tolerances are wide enough where they should not be a concern.

  • Thanks .
    No power savviest here – so we need a tool, specifically for the transformer.
    (this task gets harder since I'm looking for OTS transformer)

    I tried Excel tool for UCC2871x (UCC2871X Calculator) but it yields negative results for low input voltages as 42Vdc.
    Please advise about additional tools.
  • The design calculator is designed for the more typical and conservative input range. However, the datasheet of the UCC28713 does have a section called "Detailed Design Procedure" on page 18 (and page 18 again for the UCC28700) which I would recommend using in place of the design calculator in this case.

    The PMP10200 reference design you mentioned has the ultra-wide input range and uses the UCC28700, which is in the same family of the UCC2871x. The main differences between these parts is the High Voltage startup switch that the UCC28713 has and its maximum switching frequency, which is 100kHz.

    TI also offers PSpice models should you want to simulate your design.
  • Also, if you want to know how to contact a transformer vendor to partner in your design or understand how to change transformers from TI reference designs to suit your needs, look at this post: