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DS90UB913A-Q1 / power sequence

Ryuji
Guru 20090 points

Other Parts Discussed in Thread: DS90UB913A-Q1

Hello,

In the datasheet P.53 9.1.2, there is the discription of  "the VDDIO supply needs to reach the expected operating voltage (1.8 V or 3.3 V) before the other supplies (VDDn) begin to ramp.".
I understood that we must ramp up the VDDIO supply at first ,  if we use 1.8V power supply only.

Could you please let me know the reason that why the VDDIO supply needs to reach the expected operating voltage before the other supplies begin to ramp even so VDDIO is 1.8V?

Also, could you please let me know the timing requirement of power up sequence?
I understood that the order but there is no timing requirement.


Best Regards,
Ryuji Asaak

  • 0
    TI__Expert 5210 points
    Hello Ryuji,

    Whether the VDD_IO is 1.8V or 3.3V, it MUST ramp up first before the VDD_CORE supply and PDB pin. This is necessary for either the 913A or 914A to power-up properly because of how our internal circuitry works on both devices.

    A good rule of thumb for the timing requirement of the power-up sequence is to include >= 100 uS of delay between VDD_IO reaching 1.8V or 3.3V and VDD_CORE reaching 1.8V. This >= 100uS of delay is also recommended between the ramp of VDD_CORE to 1.8V and the ramp of the PDB pin to VDD_IO (1.8V or 3.3V).

    -Sean
  • 0 in reply to Sean Thornton1
    Guru 20090 points
    Hello Sean san,

    Thank you for the reply.I understood.

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Sean Thornton1
    Guru 20090 points
    Hello Sean san,

    Thank you for the reply.
    I understood that the timing between VDD_IO reaching 1.8V or 3.3V and VDD_CORE reaching 1.8V.

    If yes, could you please let me know the time between VDD_IO reaching 1.8V or 3.3V and VDD_CORE begin to ramp?
    Is this 0s?

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Expert 5210 points
    Hello Ryuji san,

    Typically yes, as shown in the power-up sequencing diagram above this time is recommended to be 0 seconds.

    -Sean
  • 0 in reply to Sean Thornton1
    Guru 20090 points

    Hello Sean san,

    Thank you for the reply. I got the additional question from the customer...
    Could you please let me know the expected impact If we ramp up the all of 1.8V supply(VDDIO , other VDD)  at same time?

    Best Regards,
    Ryuji Asaka

  • 0 in reply to Ryuji
    TI__Expert 5210 points
    Hello Ryuji san,

    If both supplies are ramped up at the same time, TI cannot guarantee reliable operation of the part. There might be the possibility that it works or it might not which is why we recommend the power up sequencing diagram (VDDIO ramps first, VDD_CORE ramps second, PDB ramps third) in the datasheet to ensure reliability.

    Possible impact could be bit errors, unstable LOCK, etc. if the recommended power up sequencing is not followed.

    -Sean
  • 0 in reply to Sean Thornton1
    Guru 20090 points
    Hello Sean san,

    Thank you for the reply.
    I understood.

    Best Regards,
    RYuji Asaka
  • 0 in reply to Sean Thornton1
    Guru 20090 points
    Hello Sean san,

    I got the additional question from the customer.
    If we use DS90UB913A-Q1 on the VDDIO=1.8V, are there any concerning which doesn't have concern when the VDDIO=2.8V/3.3V?

    In general, there is no power sequene requirement, if VDDIO potential is same with VDDCORE.
    However, DS90UB913A-Q1 must ramp up the VDDIO firstly if these potentials are same.
    They worry whether there is the special restrict when they use the device with VDDIO=1.8V.

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    Guru 20090 points
    Hello Sean san,

    Sorry for bothering you.
    But Could I have your reply please?

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Expert 5210 points

    Hello Ryuji-san,


    My apologies for the delayed reply. Even if VDDIO = VDD_CORE = 1.8V, we still recommend a 100 uS timing delta in between each supply to ramp.

    -Sean

  • 0 in reply to Sean Thornton1
    Guru 20090 points
    Hello Sean san,

    Thank you for the reply.
    I understood.

    Best Regards,
    Ryuji Asaka