1Gb : x4, x8, x16 DDR3 SDRAM
On -Die Te rm in a t io n (ODT)
Asyn ch ro n o u s ODT Mo d e
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
precharged power-down standby (via MR0[12]). Additionally, ODT operates asynchro-
nously when the DLL is synchronizing after being reset. See "Power-Down Mode" on
page 151 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
t
t
by analog time. The timing parameters AONPD and AOFPD (see Table 82 on page 173)
t
t
replace ODTL on/ AON and ODTL off/ AOF, respectively, when ODT operates asyn-
chronously (see Figure 119 on page 173).
t
The minimum RTT turn-on time ( AONPD [MIN]) is the point at which the device termi-
nation circuit leaves High-Z and ODT resistance begins to turn on. Maximum RTT turn-
t
t
on time ( AONPD [MAX]) is the point at which ODT resistance is fully on. AONPD (MIN)
t
and AONPD (MAX) are measured from ODT being sampled HIGH.
t
The minimum RTT turn-off time ( AOFPD [MIN]) is the point at which the device termi-
t
nation circuit starts to turn off ODT resistance. Maximum RTT turn-off time ( AOFPD
t
t
[MAX]) is the point at which ODT has reached High-Z. AOFPD (MIN) and AOFPD
(MAX) are measured from ODT being sampled LOW.
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1Gb_DDR3_5.fm - Rev. D 8/1/08 EN
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