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Original question:

XIO2001: Power-up Sequence, PCIR

XIO2001: Power-down sequence, PCIR and 3.3V/5

Oba
Genius 17605 points
Part Number: XIO2001


Hello,

I have some questions for power-down sequence for XIO2001.
The datasheet requires removing PCIR before 3.3V/5V removing like the below figure from the datasheet.


Does it mean PCIR must reach at 0V before starting 3.3V/5V down sequence?
If yes, completely 0V is sometimes difficult. What voltage can be thought as 0V? 
Or 3.3V/5V can start down-sequence when PCIR reach at a certain voltage?
If so, what is the certain voltage?

Regards,
Oba

  • 0
    TI__Guru 64326 points

    Oba,

    The recommend value would be 0 V and this would be sure to not cause issues with the power down sequence. I cannot recommend a specific value and guarantee correct functionality of the device. We do not have a defined voltage for this situation, where PCIR can be thought of as low and be greater than 0 V. PCIR is considered a power pin and not a digital signal so this thinking cannot translate directly. That being said if you start to ramp down the 3.3 V and 1.5 V rails as close as possible to to PCIR being 0 V, maybe 10% of its original value. 

  • 0 in reply to Malik Barton57
    TI__Genius 17605 points
    Hi,

    Thanks for your reply.
    I can't understand the last line in your reply,
    "That being said if you start to ramp down the 3.3 V and 1.5 V rails as close as possible to to PCIR being 0 V, maybe 10% of its original value."

    What does it mean, especially "maybe 10% of its original value". 10% of what??

    Regards,
    Oba
  • 0 in reply to Oba
    TI__Guru 64326 points

    Oba,

    Sorry for not being clear, 10% of PCIR original value is what I am referring to in my previous post. In general I believe starting the ramp down of the 3.3 V and 1.5 V rails as close as possible to to PCIR being 0 V is what should be done. 

  • 0 in reply to Malik Barton57
    TI__Guru 64326 points
    Oba,

    Is any more support needed for this issue? If so please reply with any relevant details so that I can further assist you. For now I will be marking this thread as "TI Thinks Resolved".