[SI-LIST] Re: DDR2 SODIMM AT SPEEDS ABOVE 533Mbps

Hello Samuel,
I believe these buffers are strong enough to drive your 2T load.  Chances are 
you are not terminated correctly on the receive side.  What do you have for 
termination? Also what simulation engine are you using? This is not an 
endorsement (however I use the tool), QuantumSI from SISOFT is ideal for this 
type of simulation across multiple conditions/corners.
-Jory

----- Original Message ----
From: J.Jebakumar Samuel <j.jebakumarsamuel@xxxxxxxxxxxxx>
To: si-list@xxxxxxxxxxxxx
Sent: Friday, July 27, 2007 8:20:25 AM
Subject: [SI-LIST] DDR2 SODIMM AT SPEEDS ABOVE 533Mbps

I am using a Virtex-4 FPGA in a new design. I have provided two sodimm 
connectors. I am using 2T (common address and command bus)topology. I tried 
simulating it with 2GB SODIMM modules from micron. The address and command 
signals are not even passing the sstl valid levels when the speed is beyond 
200MHz. But below 200MHz it is operating fine.  I am planning to operate the 
SODIMM's at 666Mbps.  In simulation we used, SSTL18_IO, SSTL18_I_DCI_O, 
SSTL18_II_DCI_O buffers but the results are the same. The routed trace length 
is just less than 5inches.
Thanks
Samuel
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