• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 63 subscribers
  • Views 421 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS51206: Power-Up Sequence

Brad Griffis
Guru*** 125430 points
Part Number: TPS51206
Other Parts Discussed in Thread: TPS51200,

I'm trying to understand if it is acceptable to power up the device in this order:

  1. VLDOIN + VDDQSNS
  2. VDD + S3 + S5

This is admittedly the same question as has already been asked here.  However, I didn't understand that response.  Edwin Zang said it was ok, but then said to refer to Figure 23 of the data sheet.  Figure 23 shows VDD first, so I felt that answer was inconsistent.

If it is not asking too much, I have the same question (more or less) regarding the TPS51200.

Thank you,
Brad

  • 0
    TI__Guru*** 125430 points
    For the TPS51200, I found the following note in the data sheet:

    "VLDOIN can ramp up earlier than VIN if the sequence in Figure 19 and Figure 20
    cannot be used."

    So it seems like it's ok for the 1.35V rail to come on before the 3.3V rail in the case of the TPS51200.

    I don't see any similar statement for the TPS51206. Is it not allowed for VLDOIN to come on before VDD for the TPS51206? There are some alternative options given in Section 7.3.6 (Power on and off sequence) of the TPS51206. The alternative sequence given is:

    Power up
    VDD+S3+S5 -> VLDOIN+VDDQSNS

    Power off
    VDD+S3+S5 -> VLDOIN+VDDQSNS

    It's odd that we would specify the same order for both power on and power off. Usually those are opposite order. I'm hoping that perhaps we made a typo for the Power Up sequence and intended to say that it's ok to turn on VLDOIN+VDDQSNS first, and then to turn on VDD+S3+S5.
  • 0
    TI__Mastermind 24075 points
    Hi Brad,

    From TPS51206 side, it is fine to power on with below sequence.
    1.VLDOIN + VDDQSNS
    2.VDD + S3 + S5

    One thing to be aware is VTT will rise up quickly. The VTT charging current is its current limit (minimum 2A).

    Thanks
    Qian
  • 0 in reply to Qian Chen
    TI__Guru*** 125430 points

    Qian Chen said:
    From TPS51206 side, it is fine to power on with below sequence.
    1.VLDOIN + VDDQSNS
    2.VDD + S3 + S5

    That's good news.  Is that in the data sheet? (I couldn't find it.)  If not, can we please add it?  

  • 0 in reply to Brad Griffis
    TI__Mastermind 24075 points
    Hi Brad,

    It is not in the datasheet now.
    We will discuss and consider it during next datasheet update.

    Thanks
    Qian
  • 0 in reply to Qian Chen
    TI__Guru*** 125430 points
    Thank you. In my opinion that's an important addition. I hope it gets added.