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TPS54627: Soft start requirement

Shifali N
Expert 2135 points
Part Number: TPS54627

Hi,

I am using TPS54627DDA in my design. I have set the soft start limit to seconds. I would like to know whether soft-start is the time taken for the output to reach 85% of the VOUT, 90% or 100% of the Vout value.

Vin=12V

Vout=5V

  • 0
    TI__Genius 15647 points

    Hi Shifali,

    Thanks for your question!

    Generally customers don't care much about SS time accuracy. So we don't specify the SS time limit of TPS54627.

    To give you a reference, I did bench test on TPS54627EVM board. The SS time is about the time from 0% Vout to 90% Vout. 

  • 0 in reply to Miranda Gu
    Expert 2135 points

    Hi Miranda,

    I would like to know when does the soft start timer gets enabled. I am enabling this regulator using first regulator in my board. The output voltage of first regulator is 5V. The VIH(min) for enable pin =1.6V.

    So whether the soft start timer starts as soon as enable pin voltage becomes 1.6V or whether it will wait till enable pin voltage to become 5V. kindly confirm.

  • 0 in reply to Shifali N
    TI__Genius 15647 points

    Hi Shifali,

    Understood your question.

    I will do bench test and feedback to you by 1/13.

  • 0 in reply to Miranda Gu
    TI__Genius 15647 points

    Hi Shifali,

    When EN voltage reached VH threshold, after a delay time (to wait internal circuit ready), SS time will start.

    I have some start-up waveforms for your reference.

    • EN rising to 1.6V quickly

    • EN rising to 1.6V slowly