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Lower temperature issue with AM3505 DDR2

Bipin Bopaliya
Prodigy 160 points
Other Parts Discussed in Thread: AM3505

Hello.

I have used AM3505 with DDR2. DDR2 works fine on higher temperature but it fails at <5C. Both AM3505 and DDR2 chips are industrial grade parts (should support up to -40C). I have verified timing and layout - not found anything wrong. Does anyone have faced same issue? Please refer below schematic. I can share layout if required.

 

5415.DDr.pdf

 

Regards,
Bipin

  • 0
    Prodigy 160 points

    We have found the issue.

    I patched 10 Ohm series termination on all 4 DQS lines and it is working at lower temperature. Checked up to -25C on 2 boards.

    it is surprising. Datasheet of AM3505 do not suggest termination. It clearly mentions that terminations can added only for better EMI/EMC and not required for signal integrity.

     

    I cross checked same with Sitara EVM made by Logic PD. EVM has 10 ohm series termination on DQS. I replaced it with 0 Ohm and it is even not working at room temperature.

    I am not convinced that termination on DQS lines are such critical and afraid that there could be some other reason behind this issue.

     

    Does anyone has same observation? I do not want to go for layout changed before having confirmation from TI.

     

    Regards,

    Bipin

     

     

  • 0
    Prodigy 30 points

    hello:

            Did you have solve thehe lower temperature issue?  I have the same issue,and I hope you can give me some suggestions. Thanks!

  • 0 in reply to alan ma
    TI__Guru**** 393215 points
    Hi Alan,
     
    Did you try placing 10Ohm serial resistors on the DQS/DQSn lines? On the Craneboard there are also 10Ohm serial resistors on the DM, CK/CKn and STREN/STREN_DLY lines.
  • 0 in reply to alan ma
    Prodigy 160 points

    Hi Alan,

    Yes, problem is solved by placing 10 Ohm series resistors on CK and DQS lines. I have produced thousands of boards after this change and not found this problem again.

    Regards,

    Bipin

  • 0 in reply to Bipin Bopaliya
    Prodigy 30 points

    Thank you ,the program is solved according this way.