• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 40 subscribers
  • Views 300 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TIDA-00281: Input Power PI Filter Calculation

Dan Lucas
Prodigy 10 points
Part Number: TIDA-00281

I am looking for the design guide on the input power filtering used in the 48V controller reference design (Sections  4.3.3 & 4.5.1 of TIDA-00281). On page 2 of the schematic document (TIDRIN2) it says :

"According to EMI filter calculations the electrolytic capacitors need to be at least 4xtotal input capacitance for a switch-mode power supply. See Design Considerations for calculation." 

I cannot find the calculations and I would like to understand how to properly size the inductor and capacitor for filtering. 

  • 0
    TI__Intellectual 2100 points

    Hi Dan,

    Thank you for reaching out! More information is available on choosing the components in the design guide. Specifically, section 4.3.3 on page 19 discusses the input filtering components.

    TI also offers a power stage designer tool you could use to help size components for future designs.

    Best,

    Alex Weaver

  • 0 in reply to Alex Weaver
    Prodigy 10 points

    Hi Alex,

    Thanks for the reply. I suppose we're talking about the same design guide, but I thought there would be another covering the filter design calculations per the note for the electrolytic capacitors. I'm starting to believe that's not the case. 

    The first link in the similar topics opened by John Pan poses a similar question to mine, and the answer he was given was to design the filter around the system level noise filtering requirements. It makes sense, I was just hoping to see a reference walkthrough of the design and calculation process.

    Thanks,

    Dan

  • 0 in reply to Dan Lucas
    TI__Intellectual 2100 points

    Hi Dan,

    Thank you for the clarification. It does not look like there is a separate document for designing the filter components on the TIDA-00281 product page, but we do offer an article on EMI filter components: Link. The Filter Damping section on page 3 discusses using a parallel RC circuit to replicate the characteristics of an electrolytic capacitor. The sizing of the RC components is also discussed.

    I hope this helps you out! Please let me know if you have any other questions.

    Best,

    Alex Weaver