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WEBENCH® Tools/TPS54561: Negative gain margin?

Oguzhan Orhan
Prodigy 60 points
Part Number: TPS54561


Tool/software: WEBENCH® Design Tools

Hello,

I try to design a DC/DC converter from 28V to 18.5V with switch mode regulator which can supply 2A current. When I use Webench tool to design and see the performance of the circuit, I got -25dB gain margin in Operating Values. If I manufacture this circuit, do I have a stabilization problem? Do you have suggestion for values of minimum gain margin and phase margin for a stable system?

Thanks,

Oguzhan

  • 0
    TI__Guru**** 191445 points
    Minimum phase margin is usually 45 degrees. With some control types with constant on time like DCAP2, you can allow less phase margin safely. Gain margin is usually specified as -12 dB or greater. For some control control types like DCAP2, gain margin is not a meaningful specification, as phase does not drop towards zero until Fsw/2.

    -25 dB is more than enough gain margin for your design.