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UCC28064: Audible frequency band

Masazumi Ishii
Genius 3945 points
Part Number: UCC28064

Hello.

I have a question about UCC 28064.

The frequency of the UCC 28064 varies with operation.
At this time, I want to avoid entering the audible frequency band.
I would like to make it at a higher frequency than at least 30 Khz - 50 Khz.
What kind of method is there?

Thank you.

  • 0
    TI__Mastermind 34465 points
    Hello Masazumi Ishii
    Use the calculator tool for this device and set the minimum operating frequency at your desired value.
    This is an input required by the calculator.
    If you use 30kHz then the switching frequency will be well above the audio band and you will not have a noise issue
    Regards
    John
  • 0 in reply to John Griffin1
    Genius 3945 points

    Hello.

    Thank you for your answer

    Is to do with calculated TOOL, is it an Excel based thing?
    Is it also released?

    thank you.

  • 0 in reply to Masazumi Ishii
    TI__Mastermind 34465 points

    Hi,

    Attached is a copy of the calculator

    You will also find it on this TI webpage

    SLUC645.xlsx

    Regards

    John

  • 0 in reply to John Griffin1
    Genius 3945 points

    Hello.

    John-san.

    Thank you for answering

    I used a calculation tool.

    When you input Minimum Switching Frequency with 100 kHz or 200 kHz with this TOOL, the inductance of L1 and L2 changes.
    What does this mean?
    Is it OK?

    Also, will it operate at 100 kHz or 200 kHz?
    What is the upper limit of the lowest frequency?
    Thank you.

  • 0 in reply to Masazumi Ishii
    TI__Mastermind 34465 points
    Hello Ishii-san
    Sorry about the delay in answering.
    You need to set the minimum frequency much lower than 200kHz. If you set it at 200kHz then the switching losses will be very high because in a transition mode controller the switching frequency varies over the AC line cycle. It will vary from 200kHz to many times this value.
    Normally you set the minimum switching frequency at 20kHz or above. This is the upper limit of the audio band so that the user will not be able to hear the audio noise caused by switching.
    As you increase the minimum frequency you will find that the value of the inductance decreases. This is because higher frequencies require less inductance
    Regards
    John