Hi Wang
You can very well reproduce such scenario in simulation and root-cause
issue with proper models. DDR3 four-DIMM design working without any issue
does not imply that DDR2 design will also work. you need to properly
investigate the issue with your topology. DDR2 has different routing
topology (star) compared to DDR3 (daisy-chain). amount of loading is much
higher in DDR2.
Thanks
Sanjeev Gupta
www.sigintegrity-solutions.com
On Wed, Jun 29, 2016 at 2:04 PM, Wang Xiaoguang <
xiaoguang.wang@xxxxxxxxxxxxxx> wrote:
Hi all expert,
I am doing the application test for ddr3 and ddr2 UDIMM module, but some
problem makes things confused:(two platform : INTEL, AMD, both have 4
module slot )
For ddr2, it always hang up if 4 modules are pluged in together ,however
it can work if one of 4 modules is removed from the MB (3 modules works),
And what's strange is that such fail can't be improved by change of
frequency, VDD, Temperature...
But for DDR3, there is no such problems.
From my side, I think ,
maybe the odt resistance of ddr2 is not ok that makes signal weak at DRAM
interface when work for the full load(4 modues together),
and for ddr3, it can work because there is calibration for ODT, which can
help to adjust the signal quality.
But not sure about the rootcause,
It there some comments/explanation/advise from your experience?
Wait for reply.
Best Regards
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