What is Dynamic ODT - For DDR3, Dynamic ODT (Rtt_Wr) will allow the DRAM to change ODT values during a WRITE command without a MODE REGISTER SET command. When Rtt_Wr and Rtt_Nom are both enabled, the DRAM will change from Rtt_Nom to Rtt_Wr at the beginning of the WRITE burst. After the burst, ODT will change back to Rtt_Nom. Rtt_Wr can be used independently of Rtt_Nom, but termination will be on WRITEs only.
The termination values for DDR3 are:
Rtt_Nom of 120, 60, 40, 30, and 20 ohms.
Dynamic ODT (Rtt_Wr) values are 120 and 60 ohms.
(Keyword search: What is ODT, DDR3 Termination, DDR3 Rtt_Wr, DDR3 Rtt_Nom, DDR3 Rtt)