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VTT current

KANJI SHIBATANI
Mastermind 6205 points
Other Parts Discussed in Thread: DLPC200, TPS51100, TPS51116

Hello

Would you please let us know the VTT supply Current  for  DLPC200 and  DDR2 ( MT47H32M16HR-3)?

In the oteher word,  the Light Commander  has  two VTT current source (TPS51100), but would you please let us know

the supply current for  each  VTT_B2  and VTT_B3_B4?

( it is too hard to measure it  by ourselves.)

                                DDR#　　　　　　　　TPS51116 on LC
B2:DDR_D[15:0]　　　U8                         U501
B3:DDR_D[39:16]      U7, U6                 U503
B4:DDR_D[63:40]　　 U6、U5　             U503

The reason why is customer start the desgin, but there are no description about  this value.

With my best regards

  • 0
    TI__Guru 54605 points

    Shibitani-san,

    Thank you for your inquiry.  The DLPC200 Chipset was designed by TI, but the LightCommander Controller Board was designed by Logic PD.  An inquiry has been submitted to Logic PD regarding the current on these two supplies.  This will be updated when we receive their response.  Thank you for your patience.

     

    Fizix

  • 0 in reply to Fizix
    Mastermind 6205 points

    Dear Fizix san

    Thank you for your reply.

    I had tried to measure VTT current on Lightcommander by myself, however TPS51100 VTT  output pattern tied to DDR directly, so it was really very hard .

    Cusomter know TPS51100 can handle 3A  peak sink/source current,  and also they will use TPS51100&TPS51116 in their design,

    but want to know the actual (average)  VTT current for DLPC200& DDR2 in order to estimate  the heat/relaiability.

    Anyway,I found following desciprtion on NS website. 

    According to this document, In DDR case, VTT current should be 200mA range, and there are no  concern for customer's design.

    Cusomter think 200mA average current is acceptable , however, VTT current on VTT_B3_B4 on Lightcommander exceeds 1A  average?

    http://www.national.com/assets/en/appnotes/AppBrief113.pdf

     

    Would you please give me your comment/opinion? 

    Best Regards

  • 0 in reply to KANJI SHIBATANI
    TI__Guru 54605 points

    Hello Shibatani-san,

    You wrote:

    VTT current on VTT_B3_B4 on Lightcommander exceeds 1A  average?

    Is this "1A" a measured value? 

    Best Regards,

    Fizix