1Gb: x4, x8, x16 DDR3 SDRAM
Asynchronous ODT Mode
Asynchronous ODT Mode
Asynchronous ODT mode is available when the DRAM runs in DLL on mode and when
either RTT,nom or RTT(WR) is enabled; however, the DLL is temporarily turned off in pre-
charged power-down standby (via MR±[12]). Additionally, ODT operates asynchronous-
ly when the DLL is synchronizing after being reset. See Power-Down Mode (page 183)
for definition and guidance over power-down details.
In asynchronous ODT timing mode, the internal ODT command is not delayed by AL
relative to the external ODT command. In asynchronous ODT mode, ODT controls RTT
by analog time. The timing parameters tAONPD and tAOFPD replace ODTLon/tAON
and ODTLoff/tAOF, respectively, when ODT operates asynchronously.
The minimum RTT turn-on time (tAONPD [MIN]) is the point at which the device termi-
nation circuit leaves High-Z and ODT resistance begins to turn on. Maximum RTT turn-
on time (tAONPD [MAX]) is the point at which ODT resistance is fully on. tAONPD
(MIN) and tAONPD (MAX) are measured from ODT being sampled HIGH.
The minimum RTT turn-off time (tAOFPD [MIN]) is the point at which the device termi-
nation circuit starts to turn off ODT resistance. Maximum RTT turn-off time (tAOFPD
[MAX]) is the point at which ODT has reached High-Z. tAOFPD (MIN) and tAOFPD
(MAX) are measured from ODT being sampled LOW.
PDF: 09005aef826aa906
1Gb_DDR3_SDRAM.pdf - Rev. L 03/13 EN
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