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UCC28951: About 9.1 application information

Shunnosuke Maki
Prodigy 320 points
Part Number: UCC28951
Other Parts Discussed in Thread: UCC28950

1.How to change structure in case of using non-isolated amps.

my customer read highlighted sentence in 8.1 and decided to use non-isolated amps.

" The controller device is located on the secondary side of converter, although it could be placed on primary side as well."

And so now they must change circuit structures around VSENSE.

Would you give us circuit when amps are not isolated?

2)Current sense

My customer using a current trans in their application but what does the input configuration for the UCC28951 change

when they uses a Hall element type current sensor?

 

3)Secondary rectification method

In application, customer use the center-up method, but because of the high voltage,

customer would like to use the full bridge rectification method.

In this case, can they use the output OUTE and OUTF for synchronous rectification?

  • 0
    TI__Guru* 85616 points

    Hello,

    1.  The circled components are isolated gate drivers and not op amps.  The UCC28951 will require gate drivers to drive the H Bridge and cannot be drive directly from the controller.

    2.  We recommend using a current sense transformer.  TI does not have any information on how to use a hall effect sensor with the UCC28951.

    3.  The SR drivers where designed for a voltage doubler or current doubler.  TI does not have any application information in how to use this with a full bridge output rectifier or how well it would work.  The customer is welcome to experiment to see if they can get the UCC28951 to work in a PSFB with full bridge output recitifure.

    Regards,

     

  • 0
    TI__Prodigy 320 points

    Hi Mike,

    Thank you for answers.

    >>1.  The circled components are isolated gate drivers and not op amps. 

    >>The UCC28951 will require gate drivers to drive the H Bridge and cannot be drive directly from the controller.

    Sorry for my confusing. would you have circuits or reference designs ,which UCC28951 is on primary side?

    >>2. We recommend using a current sense transformer.  TI does not have any information on how to use a hall effect sensor with the UCC28951.

    could you tell me how to design current feedback or do you have application note about this?

    using a current sense transformer is also ok. do you know how to design with it?

    BRs,

    Maki

  • 0 in reply to Shunnosuke Maki
    TI__Guru* 85616 points

    Hello,

    We do have an application note for the UCC28950/1 devices that I have attached.  It discusses how to compensate the feedback loop using a current sense transformer.

    UCC28950 600-W, Phase-Shifted, Full-Bridge Application Report (Rev. C).pdf

    Regards,