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TPS7H4104-SEP: Control Loop Bode Plot Measurement Data

Nabil Mohammad
Prodigy 10 points
Part Number: TPS7H4104-SEP

Tool/software:

Hello, 

I was wondering if you could explain the phenomenon of this flat line on the total loop measurement. Typically for a compensated current-mode regulator, we have roughly a straight line but the plot in the datasheet shows that there's a flat line on the magnitude below 1kHz. 

Could you please explain why this is the case?

  • 0
    TI__Expert 5081 points

    Hi Nabil,

    Current-mode regulators do not inherently have a pole a 0Hz, so depending on the configuration of the converter that pole can be seen at higher frequencies like in the above plot. Sometimes this pole is at a very low frequency, so the plot looks like it has a constant slope from the very beginning. If that pole is at a high enough frequency, then the flat part of the gain curve will be visible on the plot.

    "Understanding and Applying Current-Mode Control Theory" is a great document that also contains the transfer functions of various current mode converter topologies if you are interested in learning more.

    Thanks,

    Andy