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CoC Level V Tier 2 compliant power supply reference design

Michael Gambuzza
Prodigy 100 points
Other Parts Discussed in Thread: UCC28780, PMP9041, PMP, UCC28704

Hello:

I am looking to design a CoC level V Tier @ compliant wall adapter having the following specs:

1. Universal AC input 90VAC to 265VAC or whatever universal means today.

2. 24VDC output 2A

Must be able to meet emerging EU standards for efficiency. Looks like LTC/ADI is out how about TI? I noticed a 65W design at 19.2V. Can this be adapted to my spec?

Thanks all!

  • 0
    TI__Expert 5910 points
    Hello Michael,

    Here is a design that might work for you

    http://www.ti.com/tool/PMP9041

    Another option would be to look at the UCC28780 to make an Active Clamp Flyback. This would be higher efficiency, but more complicated and costly.

    Thanks,
    Robert
  • 0 in reply to Robert Taylor1
    Prodigy 100 points
    Robert:

    Thanks for the reply. I like the PMP9041 schematic but I do need up to and including 2.0 A operation. Will that design work? It looks like it current limits at 2 A. Do you think that topology is acceptable for a Wall wart power cube that will be sold globally? Also is it very difficult to pass all the conducted emissions tests? I'm assuming this meets the emerging CoC tier 2.

    I ordered a UCC24630EVM and was considering that design but the PMP looks less expensive.

    Thanks again look forward to your reply.
  • 0 in reply to Michael Gambuzza
    TI__Expert 5910 points
    Hi Michael,

    I have asked the original designer for PMP9041 to comment, please wait a bit.

    Thanks,
    Robert
  • 0 in reply to Robert Taylor1
    TI__Intellectual 2855 points

    Hi Michael,

    Yes, this design can be stretched to 2A.  Everything will get a little bit hotter, especially the output diode.  To get some margin on the constant current regulation, I recommend dropping the current sense resistor (R8) to around 0.24 ohms.  This design does meet the CoC tier 2 efficiency requirements.  If you want to reduce cost, you could replace the controller with our newer UCC28704 controller.  

    To semi-quote Forest Gump: EMI is like a box of chocolates, you never know what you are going to get.  We have provided some EMI data in the test report for this reference design, but it is not quite under the Class B limits and the input filtering may need to be adjusted for your end application.  When you re-package the design for your form factor, the EMI will change.  Also, transformer construction will have a huge impact on EMI results.

    regards,

    Brian