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Question of TPS51100

Takahiro Nishizawa
Genius 5575 points
Other Parts Discussed in Thread: TPS51200, TPS51100

We have a question.

Please tell us the VTTREF variation when VTTREF is 0.675V.

We want to know accuracy about VTTREF.

Best regards,

Takahiro Nishizawa

  • 0
    TI__Mastermind 24075 points

    HI Takahiro,

    The VTTREF varation data is not available when VTTREF is 0.675V.

    For DDR3L application, can you consider TPS51200?

    Thanks

    Qian

  • 0 in reply to Qian Chen
    Genius 5575 points
    Thank you for your answer!

    TPS51100 is actual product in our customer.

    Our customer needs ±2% accuracy when VTTREF is 0.675%.
    Do you have any information about accuracy of VTTREF?

    In datasheet p.5 "Output votlage tolerance to VTTREF, VTT",
    Can you infer the VTTREF accuracy?

    Best regards,


    Takahiro Nishizawa
  • 0 in reply to Takahiro Nishizawa
    TI__Mastermind 24075 points
    Hi Takahiro,

    The VTTREF tolerance spec in datasheet is tested with +/10mA current.
    On datasheet spec, with VDDQ=1.5V, VTTREF=10mA, the VTTREF tolerance is +/-15mV.

    In DDR3L (VDDQ=1.35V) application, the VTTREF current drawn by DIMM is only a few uA, so I expect the VTTREF tolerance can meet +/-2%*675mV =+/-13mV.

    How much is the VTT current in customer's applicaiton?


    Thanks
    Qian
  • 0 in reply to Qian Chen
    Genius 5575 points
    Thank you for your answer!

    I have a new question about TPS51100.

    Please tell us the accuracy of VTT when VLDOIN is 1.35V.
    In your answer, accuracy of VTTREF is +/-2%.
    Is it +/-2% about VTT?

    Best regards,


    takahiro Nishziawa
  • 0 in reply to Takahiro Nishizawa
    Genius 5575 points
    Thank you for your support!

    Please tell us your answer.


    Question 1.
    Please tell us the accuracy of VTT when VLDOIN is 1.35V.
    In your answer, accuracy of VTTREF is +/-2%.
    Is it +/-2% about VTT?


    question 2.
    Please tell us the efficiency under the following conditions.

    VDDQSNS=1.35V
    VTT : efficiency ?%
    VTTREF : efficiency ?%

    And do you have any document that efficiency of VTT and VTTREF when VDDQSNS is 1.35V?


    Best regards,


    Takahiro Nishizawa
  • 0 in reply to Takahiro Nishizawa
    TI__Mastermind 24075 points
    Hi Takahiro,

    1. Sorry, we don't have VTT variation test data at VLDOIN=1.35V conditon.

    2. TPS51100 is linear regulator, the VLDOIN current is equal to VTT current, therefore the efficiency is VTT/VLDOIN=50%.
    The VTTREF current is very small, the power loss on VTTREF can be ignored.

    If possible, we suggest to promote TPS51200 to customer for DDR3L application.
    TPS51200 is a very popular device being used by a lot of customers in huge quantity.

    Thanks
    Qian
  • 0 in reply to Qian Chen
    Genius 5575 points
    Thank you for yur answer!

    TPS51200 has no adoption record.
    but we want to promote TPS51100.

    About question 1.
    Do you know the reference value about VTT variation?

    About Question 2.
    Do you have waveform or document about efficiency?


    Best regards,


    Takahiro Nishizawa
  • 0 in reply to Takahiro Nishizawa
    TI__Mastermind 24075 points
    Hi Takahiro,

    1. The VTT variation is availabe on datasheet page 5.
    At VLDOIN=1.5V, the VTT variation is +/-30mV with +/-1A load. I think this value can be referred for 1.35V VLDOIN.

    2. I don't have the data on hand, but we are quite sure that the efficieny is VTT/VLDOIN.

    Btw, how much is VTT current in customer's application?
    Why TPS51200 is not preffered, techinical reason or businees reason?

    Thanks
    Qian