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TPS54678: Switching frequency

Onur Kusakoglu
Intellectual 965 points
Part Number: TPS54678


Good morning,

What is the IC switching frequency tolerance while setting the switching frequency with a resistor?

In the data sheet, with a 82.5kΩ the range is stated as 400-600 kHz with a typical value of 500 kHz.

I have a different resistor and my actual switching frequency is a bit of than calculated value.

Best Regards

Onur

  • 0
    TI__Mastermind 26500 points

    Hi Onur,

    Yes that's right! With a 82.5kΩ the range is stated in the d/s as 400-600 kHz with a typical value of 500 kHz.

    The switching frequency of the TPS54678 is adjustable over a wide range from approximately 200 kHz to 2000 kHz. Are you able to get the fsw in this range and what was the resistor used?

    There could be slight variations in the switching frequency depending on the resistor tolerance, load conditions, temperature, etc.

    Regards,

    Febin

  • 0 in reply to Febin
    Intellectual 965 points

    Hi Febin, 

    Yes, that is exactly what I am trying to figure out. My resistor is 42k2 and my expected switching frequency is 924-943 kHz due to %1 tolerance and what see on my measurement is 900 kHz. I know this is already okay, but I just want to understand where this tolerance come from and what should be the expected tolerance so I can define an accepted range.

    Best regards

    Onur

  • 0 in reply to Onur Kusakoglu
    TI__Mastermind 26500 points

    Hi Onur,

    I will provide a feedback before end of this week.

    Regards,

    Febin

  • +1 in reply to Febin
    TI__Mastermind 26500 points

    Hi Onur,

    Firstly, I would like to thank you for your patience and understanding.

    I tried to get more test data for TPS54678 to understand the switching frequency tolerance. Looking at the test data and datasheet, I would say that there could be an offset of +/-20% from the desired switching frequency. This could be due to resistor tolerance, load conditions, temperature, etc.

    Unfortunately, we cannot guarantee this spec. Is there any issue that your facing because of this spec range?

    Regards,

    Febin

  • 0 in reply to Febin
    TI__Mastermind 26500 points

    Hi Onur,

    I hope you could solve your problem. Due to inactivity I will go ahead and close this thread. Please feel free to reach out to us for any further support.

    Regards,

    Febin