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AM3517 DDR2 Series Termination

Prad
Expert 1125 points
Other Parts Discussed in Thread: AM3517

Hi,

Does AM3517 DDR2 interface support two- resistor network (SSTL) type of Series Termination

mentioned in the apllication report(SLLA067B) Figure 15.

Please let me know what is the recomended design for AM3517's DDR2 series termination,and if  there are any application note.

 

Thankyou and Regards.

  • 0
    TI__Genius 9190 points

    Hello,

    the AM3517 DDR2 interface does not support SST type series/parallel termination.   Pure series termination is allowed if EMI is a consideration, but this is not necessary to meet signal integrity and overshoot requirements.

    Please see section 6.4.3.1.9 of the AM3517/05 data manual for termination guidelines

    For DDR2 routing and layout guidelines please also see the AM3517/05 data manual starting as section 6.4.2.

    Best regards,
    Jeff

  • 0 in reply to Jeff Culverhouse
    Expert 1125 points

    Hello Jeff,

    Thanks for the information.

     

    Could you please let me know what is the reason behind "No terminations of any kind are required" in 

    case of AM3517, if I don't use any series resistor can I assume there won't be any noise issue. 

     

    Regards.

    Prad

  • 0 in reply to Prad
    TI__Genius 9190 points

    Hello Prad,

    With no terminations there could be an EMI noise issue.  I was just saying that the device does not need the termination as it can still meet signal integrity and overshoot requirements...basically we would still be in spec with no termination.

    I would think that you would need/want the series terminators to reduce EMI. 

    Best regards,
    Jeff

  • 0 in reply to Jeff Culverhouse
    Expert 1125 points

     

    Hi Jeff,

    Thankyou.

    The AM3517 datasheet states that the DDR2 Memory Controller supports 

    JESD79D-2A standard compliant but couldn't find the details about JESD79D-2A in JEDEC webpage.

     

    And as you know AM3517(DDR2) I/O interfaces are LVCMOS type,

    what is the merit of this type of interface when compared to SSTL type.

     

    Thankyou.

     

  • 0 in reply to Prad
    TI__Genius 9190 points

    Hi Prad,

    There is a type-o in the JEDEC number in the Data Manual...it should actually be JESD79-2A...the extra D after 79 should not be there! 

    Best regards,
    Jeff