• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 2063 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC2897A: A question of PMP6547 TI Design

Cage Chen
Prodigy 490 points
Part Number: UCC2897A

Hi,

In the PMP6547, it is a wide range input, and fix 12V, 10A design.

In the schematic, there is a R20 and L3 in parallel.

What is the purpose to have both R20 and L3?

Thanks a lot.

Best regards, Cage.

  • 0
    TI__Mastermind 27135 points
    Hi Shang Ming Chen,

    Thanks for your interest in UCC2897A. The structure formed by C23, C24, L3, C22, C21, C19 and C18 is known as a pi filter and provides better damping of high frequency noise on the input voltage than input capacitance alone would be able to provide. The reason R20 is placed in parallel to L3 is to adjust the output impedance of the filter. This is needed because if the input impedance of the power converter is close to the output impedance of the pi filter, you can get resonating behavior.

    Best Regards,
    Ben Loug
  • 0 in reply to Benjamin Lough
    TI__Prodigy 490 points
    Hi Ben,

    Thanks for your great support.
    It has solved my question.