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TPS54628: MAX Output Capacity

Shay Mor
Intellectual 870 points
Part Number: TPS54628

Hi,

What is the maximum capacity that I can put in the output rail of tps54628?

  • 0
    TI__Mastermind 18510 points

    Hi, recommend to follow table1 for the design, because LC value will impact the double pole location which related to the loop stability.

    Yuchang

  • 0 in reply to Yuchang Zhang
    Intellectual 870 points

    Hi,

    I saw the table, in the table the maximum is 68uF. 

    I have a very large board 42 x 42 [cm] and I use this output rail for all the board, 1 layer. 

    this is why i'm considering placing some large capacitor around the board, something like 22uF x8 and in additional to 2x 22uF near the output power supply.

    what is your suggested?  

  • 0 in reply to Shay Mor
    TI__Mastermind 18510 points

    Hi,

    Suggestions as below,

    1, Based on your vout to select a min value inductor follow the recommendation table, then the LC double pole can be balanced for large output caps.

    2, suggest you reserve 6x22 close to the converter output, and put 4x22 close to the loading, Feedback route back from the 6x22.

    3, Based on the test result, if some not good thing seen in the performance test, you can remove some caps to check.

    Yuchang

  • 0 in reply to Yuchang Zhang
    Intellectual 870 points

    Hi,

    I didn't understand,

    as follow the table attached, the maximum capacitors value is 68uF, you suggest is 6x22uF=132uF near the ouput and 4x22uF= 88uF close the loading

     132uF+88uF= 220uF

    please clear youer answer I must to understand what is the maximum capacity that I can assemble.

    I use 3.3V output, 2.2uH inductor.

  • 0 in reply to Shay Mor
    TI__Mastermind 18510 points

    What  I mean is limitation of L/C is to limit the LC double pole position, so if you want to use bigger Cout, you can try to use smaller L, to make LC position slight change. Even so, the caps you used is over the recommendation, considering generally there is some buffer based for the recommendation, I suggest you can reserve them, based on the test to determine use or not.

    But if you want a safe confirmation value, I suggest you can use 3pcs 22uf close to converter, put 2x22uf to the loading, this should be ok.

    Yuchang