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TPS54260 Conducted Emissions

WhiteHorse
Genius 4430 points
Other Parts Discussed in Thread: TPS54260

e2e,

We have a customer planning to use the TPS4260 in a new application.  They are concerned about conducted emissions and would like advice on developing a filter to reduce conducted emissions to a minimum in their application.  

Thanks for your help.

John Wiemeyer

  • 0
    TI__Mastermind 35165 points

    Hi John,

    Is the part number supposed to be TPS54260?

    Anthony

  • 0 in reply to Anthony F
    Genius 4430 points
    Sorry Anthony, Yes the correct part number is TPS54260.
  • 0 in reply to WhiteHorse
    Genius 4430 points

    Customer provided the following schematic of their power design.

    Regards,

    John Wiemeyer

  • 0 in reply to WhiteHorse
    Genius 4430 points
    I suggested the customer take a look at TI's AN-2162 Simple Success with Conducted EMI from DC-DC Converters.

    http://www.ti.com/analog/docs/litabsmultiplefilelist.tsp?literatureNumber=snva489c&docCategoryId=1&familyId=3058

    Is there any other information specific to the TPS54260 regarding the input filter? Also, are there any recommendations for changes to the schematic provided above?

    Thanks for your help.

    John Wiemeyer
  • 0 in reply to WhiteHorse
    TI__Mastermind 35165 points

    Hi John,

    AN-2162 is a great resource to get started with and is exactly what I was going to suggest. There's not anything specific in regards to filter design needed for the TPS54260. As the application note describes one important thing to watch out for is to make sure there is no unwanted resonance between the input common mode choke and the ceramic input capacitors. An input cap with more ESR may be needed to dampen resonance.

    Do you know the standard the customer is trying to satisfy? Specifically one thing I would like to know is the frequency range the customer needs to limit the conducted emissions in.

    Best Regards,
    Anthony

  • 0 in reply to Anthony F
    Genius 4430 points

    Anthony,

    The customer needs to pass FCC Class B Conducted emissions.  

    Regards,

    John Wiemeyer

  • 0 in reply to WhiteHorse
    TI__Mastermind 35165 points

    The guidelines presented in the app note should be adequate then. Some other standards require low conducted emissions at higher frequencies (>30 MHz) which can require more filtering.

    If he ends up needing to limit radiated emissions the first things to add are:

    1. A 10 nF or so capacitor very close to the VIN pin and GND of the catch diode.
    2. An RC snubber across the catch diode.

    Best Regards,
    Anthony