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TPS51200: VTT have leakage when VDDQ startup

Jan Bob
Intellectual 280 points
Part Number: TPS51200

Hi Expert,
We found VTT(TPS51200) has leakage when VDD ready and VTT haven't started up.
The spike of leakage will be higher when more DDR4 module available.
Would you have any ideals that will cause it?

  • 0
    TI__Mastermind 24075 points

    Hi Jan, 

    We are sure that the leakage current is from DIMM side, not from TPS51200. 

    You can use a bleeding resistor to reduce the voltage caused by leakage. 

    Thanks

    Qian

  • 0 in reply to Qian Chen
    Intellectual 280 points
    Hi Qian Chen,
    Is this a common problem with DDR module?
    Would you know the leakage reason? Is there any risk may cause TPS51200 to malfunction?
  • 0 in reply to Jan Bob
    TI__Mastermind 24075 points

    Hi Jan, 

    We see similar problem on many other customer's projects. 

    There is a leakage current path from VDDQ to VTT on DIMM. 

    As long as the VTT voltage is below VDDQ/2, it should be no risk to TPS51200. 

    You may need to check DDR datasheet or vendor if the prebias VTT voltage is fine to DDR module. 

    Usually the leakge current is small, a bleeding resistor can be used to reduce prebias VTT voltage. 

    Thanks

    Qian