SC589_EZ-BOARD uses DDR3 with series termination, Why?

Question

I'm confused. 
 SC589_EZ-BOARD uses DDR3 with series termination, 
 so why is the VTT termination method not used? 
 Also, the technical note EE-387 does not mention VTT termination at all. 
 
 Previously, I was using DDR3 with the SC584, which used series resistor termination and was functioning normally. 
 Now, I am going to use the SC598, and the reference material EE434 says to use VTT, which is confusing. 
 I understand that VTT is recommended, but why is there no mention of VTT in the SC584's documentation EE387? 
 
 Is there a difference in the electrical characteristics of the DMC between SC58x and SC59x? 
 
 Regards.

NandiniC · Answer

Hi, For DDR3/3L, VTT termination is recommended by JEDEC, as this mitigates signal reflection. The primary purpose of a VTT island is to prevent reflections at the memory device. Removing the VTT termination results in signal reflections. The removal can lead to higher than nominal voltages at the memory address or command input pins, which can damage or reduce the lifetime of the memory. Check with the appropriate memory vendor for device specific information. VTT termination does not play a major role for the ADSP-2159x/SC59x SHARC+&reg; Processor, it&rsquo;s only a requirement for the memory device. As you have already aware of EE-434, Please follow the board design guidelines for DMC. Regards, Nandini C

NandiniC · Answer

Hi Hiro, 
 VTT termination is a guideline from the memory vendors/ JEDEC, so we are just passing them along. VTT termination is recommended at higher frequency, hence we follow and recommend the same. 
 Customers of Griffin and GL could use VTT termination if they feel so. 
 Customers of 2156x/SC59x processors could also use series termination and not VTT if they perform satisfactory simulations and compliance on their board. 
 Regards, Nandini C

SLA Status	Assignee	Support Status
SLA Closed. Missed after 111 hours	Nabeel jeyanthi.jegadeesan	Open

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SC589_EZ-BOARD uses DDR3 with series termination, Why?

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