• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 62 subscribers
  • Views 169 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.

Original question:

WEBENCH® Tools/TPS54291: TPS54291 inductor & compensation values calculations

WEBENCH® Tools/TPS54291: TPS54291 questions on compensation.

Jennifer Stander
Intellectual 490 points
Part Number: TPS54291

Tool/software: WEBENCH® Design Tools

Hi,

The spreadsheet in the original post was very helpful. I didn't catch the mistake in the equations in the data sheet. When I look at the example design there are components on it that are not included in the datasheet description. Such as the series capacitor (470p) resistor (10) from SW2 to ground and the C6 / C8 capcitors across the compensation components. For C6 / C8 I am not sure how they are calculated. Will either of these affect the C1 / C2 values in the resistive divider?

I am also a little confused about what Cout is. I have Cout capcitors right at the output of the supply but then I also have bulk capacitors near the loads. Do I need to take the bulk capacitors into account when calculating the compensation. 

Thanks you,

Jennifer

  • 0
    TI__Genius 15135 points

    Hi, Jennifer 

    1. C3 and R2 forms the RC snubber which is to reduce ring on SW1/2 node. 

    I attach a file for your reference. 

    2. C6 is Comp, you can use the Equation10 to calculate it. 

    C7 and C8 is to filter noise and reduce the gain beyond the bandwidth, you can use the TI recommended value directly, usually, we set it to 10pF ~ 68pF, it doesn't affect the C1 / C2 values. 

    3. We don't need to take the load bulk capacitors into account since they aren't in the feedback loop, we just need to consider the local Cout when calculate. 

    7725.Power Tips - Calculating an R-C snubber.pdf