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TPS53355 - PG out threshold and delay time

Ryuji
Guru 20090 points

Hello,

Could you please let me know the threshold voltage and delay time when Power Good goes low ?
I calculated the threshold voltage from the datasheet. are these threshold voltage correct ?
And there is the delay time as 2us only in the pin description. Could you please let me know the min/max of this time?

-------------------------
< Threshold Voltage ( PG Threshold +/- Hysteresis) >
Out to Higher  max 120.0%
Out to Higher  typ 115.0%
Out to Higher  min 100.0%

Out to Lower max 106.0%
Out to Lower typ 90.0%
Out to Lower min 85.0%

<Delay time>
max us
typ 2us
min     ?us
-------------------------

Best Regards,
Ryuji Asaka

  • 0
    TI__Guru**** 191445 points

    I get:

    Out to Higher  max 120.0%
    Out to Higher  typ 115.0%
    Out to Higher  min 110.0%

    Out to Lower max 96.0%
    Out to Lower typ 90.0%
    Out to Lower min 85.0%

    But I am not sure how those tolerances stack up.

    As far a s delay, there is not any.  You are measuring 2 usec, but you cannot know where the actual internal threshold is,  So you do not know if it is 2 usec delay or just different threshold voltage.  I think the delay thru the comparators and control logic is very short, < 1 usec.

  • 0 in reply to JohnTucker
    Guru 20090 points

    Hello John san,

    Are these threshold worst case?


    Regarding delay time, 2us is not measured data.
    2us is described in the datasheet.And I understood that the 2us as typical value.
    From your reply, should I use 2us as maximum value?



    Best Regards,
    Ryuji Asaka

  • 0 in reply to Ryuji
    TI__Guru**** 191445 points

    That 2 usec is just in the pin description.  It is not a specification.  The levels in the datasheet are presented as minimum and maximum so they are in fact worst case.  The question is how you apply them to get the actual variation.  Do you add the maximum hysteresis to the maximum and minimum trip values?  I did not work on that datasheet so I have no idea exactly how to interpret that.  Let me see if i can find out who generated that.