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XIO2001: Power up sequence for /PERST

Oba
Genius 16545 points
Part Number: XIO2001

Hello,

 

I have a question about XIO2001 power sequence, especially /PERST deassertion timing.

 

1.

The datasheet says to wait a minimum of 100ms after applying power in the below figure (Yellow marked line)

I think this “after applying power” mean “after all 1.5V, 3.3V and PCIR power rails are stable within recommended operating condition”.

Is this my understanding correct?

 

2.

Although above datasheet description says “after applying power”, following figure 4 shows that /PERST is deasserted 100ms after /GRST.

Which is correct, “100msec after all power rails stable” or “100msec after /GRST deasserted”?

 

I know /GRST must be deasserted after all power rails stable.

So my question means that does the /PERST deassertion have to wait 100m after /GRST deassertion if all power rails are stable much before?

Regards,

Oba

  • 0
    TI__Guru 64326 points

    Oba,

    /PERST should be de-asserted after both power is stable, /GRST is de-asserted and REFCLK is stable for 100 us. After these conditions are satisfied then /PERST can be de-asserted. De-asserting /PERST before /GRST is de-asserted will cause an invalid state of XIO2001. The de-assertion requirement of /PERST is in reference to /GRST and REFCLK. 

  • 0 in reply to Malik Barton57
    TI__Genius 16545 points

    Hello

    Thanks for your reply.
    I believe I understand 100us requirement as you mentioned.
    What I want to confirm is 100ms requirement, especially start point of this 100ms.
    Could you look at the below figure that explains my question.
    The start point of 100ms for case 1 is all power rails stable point.
    The start point of 100ms for case 2 is all power rails stable and GRST is deasserted.
    Which is correct?

    Regards,
    Oba

  • 0 in reply to Oba
    TI__Guru 64326 points

    Oba,

    Case 2 is correct.