External Memory Interface Handbook Volume 2: Design Guidelines

ID 683385
Date 5/08/2017
Document Table of Contents

3.3.1. Comparison of DDR3 and DDR2 DQ and DQS ODT Features and Topology

DDR3 and DDR2 SDRAM systems are quite similar. The physical topology of the data group of signals may be considered nearly identical.

The FPGA end (driver) I/O standard changes from SSTL18 for DDR2 to SSTL15 for DDR3, but all other OCT settings are identical. DDR3 offers enhanced ODT options for termination and drive-strength settings at the memory end of the line.

For more information, refer to the DDR3 SDRAM ODT matrix for writes and the DDR3 SDRAM ODT matrix for reads tables in the DDR2 and DDR3 SDRAM Board Design Guidelines chapter.

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