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Original question:

UCC28070: Use ucc28070 in bridgeless PFC

UCC28070: Does any CCM IC support DC input?

Siliang Zhang
Prodigy 110 points
Part Number: UCC28070
Other Parts Discussed in Thread: UCC28180, UCC28063

I wonder if there is any CCM ( Single phase or interleaved) IC that support DC input. Or is there any method to use these ICs in DC input.

Does  UCC28070 work if I pull VINAC low while the input is a DC voltage?

Thanks.

  • 0
    TI__Mastermind 34465 points
    Hello Siiang,
    All of the pfc controllers were designed for 50/60Hz line frequency applications. However some testing was done with DC and 400Hz input supplies.
    The UCC28070 is the only known pfc that will not work with a DC input.
    This is because the quantized multiplier of the UCC28070 requires the VINAC input pin detects the zero crossing in order to set the correct multiplier level.
    If you pull VINAC low by some external means then the input current is set to zero. This is because you are setting the input of the current amplifier to zero. So you will see times when the DC input current turns off.
    In an AC supply this occurs naturally around the zero crossings and is exactly what you require for good power factor but in a DC supply you do not want the current turning off.
    You can use the UCC28180 with a DC input supply.
    The UCC28180 does not monitor the input and so it has no issues with DC.

    Regards
    John
  • 0 in reply to John Griffin1
    Prodigy 110 points

    thanks John,

    So that means all interleaved CCM ICs do not compatible with DC input.

    Why does 28070 have to sense ac input and 28180 doesn't?

     

  • 0 in reply to Siliang Zhang
    TI__Mastermind 34465 points
    Hi Siliang,
    No. That does not mean that all of the interleaved pfc controllers behave similar to the UCC28070. In fact the UCC28063 does work with a DC input but your question was about CCM controllers and this is a TM controller.
    If you want to know the differences between the UCC28070 and the UCC28180 you will find all this information in the datasheets.
    Hope this answers your questions.
    Regards
    John