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UCC28730: May I ask how UCC28730 can measure the phase & Gain waveform ?

Kygo Cheng
Expert 6830 points
Part Number: UCC28730

Hi Team

May I ask how UCC28730 can measure the phase & Gain waveform as follows, how to connect the external instrument on the SCH?

The datasheet only shows how to calculate, but the customer wants to measure from the outside ,THX

  • 0
    TI__Guru 66115 points

    Hello,

    Because the feedback signal is discontinuous by sensing from the output through the transformer turns ratio and aux winding and the feedback amplifier is internal it is not possible to measure gain and phase with a network analyzer.

    To check for stability you will need to do large signal line and load transients to make sure the output is stable.  If you select the output capacitor based on the data sheet recommendations your design should be stable.  You will still need to check it with large signal load transients.

    Regards,

  • 0
    TI__Mastermind 19495 points

    Hi Cheng,

    Thanks for the query. We can't measure traditional bode plot with this device or other similar PSR controllers as these are internally compensated as rightly pointed out by you. I am curious to know the source of the bode plot as I was not able to find it in UCC28730 datasheet. 

    The following app note shows a rough estimate of phase margin under transient load conditions.

    https://www.ti.com/lit/an/slva381b/slva381b.pdf

    Please let me know if you have further questions.

    Thank you

    Regards,

    Harish