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TPS548B22: Ramp Setting

Allan Fan
Expert 5730 points
Part Number: TPS548B22

Hi Expert,

Customer used TPS538B22 with condition 12Vin to 0.8Vout/20A, Fsw=650Khz.

From DS table 7 recommendation, Ramp = R/2 for Vo=0.8V but in real testing, they could pass bode plot PM>45deg criteria by increasing Rx2 or Rx3. Do you have any concerns to do that? 

Thanks,

Allan

  • 0
    TI__Genius 17905 points

    Hi ,

    The table is just giving a guideline or starting point. If the customer is satisfied with the phase margin at the higher ramp settings, then there is no issue going to the higher settings. You can see from Section 8.2.3.3.1 in the datasheet that there is a relationship between minimum output capacitance for stability, ramp time constant and other design variables, so you may be stable with higher ramp time constant for a given condition so long as the stability criteria is satisfied.

    Regards,
    Kris