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TPS54325: Frequency responce for DCAP2

Ryoma Ohashi
Expert 3315 points
Part Number: TPS54325

Hi team,

My customer is using TPS54325, which uses DCAP2 control.

For general DCDC, it is purposeful to measure the frequency responce and check the gain and phase margin to know the system stability.

But for DCAP2 control, since these DCDC has an internal phase compensation circuit in it,

my customer thinks that the it is useless to take a  frequency responce result for DCAP2.

Is this correct?

If it has a benefits for taking a frequency responce for DCAP2, could you explain why the result it usable beside the internal phase conpensation circuit.

Regards,

Ohashi

  • 0
    TI__Mastermind 24060 points

    Hi Ohashi-san,

    Yes as long as the datasheet recommended LC combinations are used, the design will be stable. As you mentioned, the TPS54325 is internally compensated and using the correct LC combination helps ensure stability. You can measure the frequency response if required to see how many gain/phase margin you have. Another option is to test out a load transient and check for any ringing during over/under shoot. 

    Thanks,

    Amod

  • 0 in reply to Amod Vaze
    TI__Expert 3315 points

    Hi Amod,

    Thanks for your answer.

    Let me confirm:

    > You can measure the frequency response if required to see how many gain/phase margin you have

    So, it means that the whole systems frequency responce result contains the effect of the internal phase compensation.

    And that result it useful to consider the stability by checking the phase/gain mirgin.

    So, the frequency responce measurement result is not useless.

    Is this correct?

    Regards

    Ohashi

  • +1 in reply to Ryoma Ohashi
    TI__Mastermind 24060 points

    Yes it is useful but not necessary to measure it if following datasheet guidelines. And yes it’ll include the effect of internal compensation. 

    Thanks,

    Amod