Motorola(Freescale) have published an introduction note about DDR, the link is http://www.freescale.com/files/32bit/doc/app_note/AN2582.pdf?fsrch=1
Also They have a note about the memory configuration's pitfalls(http://www.freescale.com/files/training_pdf/VFTF09_AN108.pdf).
I saw those yesterday but was looking for something even more basic. Just to give a general understanding before they dive into a manufacturers app note. I like parts of the Freescale presentation ... but again, too much of a deep dive and more system configuration than pcb layout. Maybe I'll have to write my own ...
If you can attend one of my training classes, I think you will find what you need.
They are offered all over North America as well as on-site.
Look at the Pro Tune Up 4 class description. The description is also attached to this email.
Let me give you the short form of the DDRx stuff here.
1. These are all single ended busses. Hence Power Delivery is critical. VTT is a real power supply for termination so make sure it is solid. VREF is not a supply. It is a reference. However, it must be a FAT trace that can take up to 3ma without any significant voltage drop.
2. These are high speed signals. Therefore you must treat them as such and follow all standard high speed routing rules. Any corss talk will eat your lunch.
3. Chips are far easier than DIMMS or RDIMMS. The problem with modules is that you will go through a connector and the Address / Bank Select Lines are referenced to power not ground comming off the RDIMM.
4. SIMULATE EVERYTHING or pay the penalty.
5. The maintaining the "Ballanced T" of DDR2 is critical. You will not get close tothe upper speed ranges unless you keep these signals ballanced.
6. If you have the choice of DDR2 over DDR ... take DDR2
7. if you have the choice of DDR3 over DDR2 ... take DDR3
Terry Fox 425 391-8696
PTU4_2009.pdf 10.9 KB
If you're still looking for information about DDR and you're a Mentor customer current on support, you can find lots of DDRx resources in TechNote MG250320. And everyone, regardless of whether they're a Mentor customer or not, can view our on-demand webcast, "Meeting the Challenges of DDRx Design."
You might also consider posting DDR questions in our SI/PI Community.