Issue with DDR II Memory Write during system bring-up

[cks3976]

Dear Group,

I am using Promos DDR -II memory V59C1512164QDJ3I in a design. We have currently made 70 prototype cards with this memory. And a significant number of cards (20%) in this lot are failing during system start-up (that is when the system is in room temperature). System log suggests that the Write to DDR-II have failed.

However after several reboots and when the system becomes bit more warm the card start functioning well (well.. most of the times).

I have tested the Card for possible drop in power or slip in the clock during start-up, but I could not see an issue.

BTW, initial spins of this Card were using DDR from a different make (Nanya) and we never faced any issue. I also tried using a Nanya device on this new set of Cards, but that failed too..

I feel the issue is not in Memory, but in the Card. Can you please suggest me what can be done further to analyze the issue ?

Thanks in advance,
CKS

 

[aggpankaj2]

1. check with the control signals
2. if there is a power up sequence, check for its timings.

 

[cks3976]

Hi,

Control Signals are fine. DDRs are being controlled by a proprietary processor. And as I have mentioned, this failure happens only on 20% of the cards. And remaining 80% of the cards do not have any issue. I checked the timing and that looks fine. And there is no power sequencing requirement..