W631GG6KB-15 Datasheet, PDF (91/158 Pages) Winbond – Double Data Rate architecture: two data transfers per clock cycle

W631GG6KB
7.19.4.3 Asynchronous to Synchronous ODT Mode Transition during Power-Down Exit
If DLL is selected to be frozen in Precharge Power Down Mode by the setting of bit A12 in MR0 to ―0‖, there is also a transition period around power down
exit, where either synchronous or asynchronous response to a change in ODT must be expected from the DDR3 SDRAM.
This transition period starts tANPD before CKE is first registered high, and ends tXPDLL after CKE is first registered high. tANPD is equal to (WL - 1) and is
counted (backwards) from the clock cycle where CKE is first registered high.
ODT assertion during the transition period may result in an RTT change as early as the smaller of tAONPDmin and (ODTLon*tCK(avg) + tAONmin) and as late
as the larger of tAONPDmax and (ODTLon*tCK(avg) + tAONmax). ODT de-assertion during the transition period may result in an RTT change as early as the
smaller of tAOFPDmin and (ODTLoff*tCK(avg) + tAOFmin) and as late as the larger of tAOFPDmax and (ODTLoff*tCK(avg) + tAOFmax). See Table 13.
Note that, if AL has a large value, the range where RTT is uncertain becomes quite large. Figure 85 shows the three different cases: ODT_C,
asynchronous response before tANPD; ODT_B has a state change of ODT during the transition period; ODT_A shows a state change of ODT after the
transition period with synchronous response.
CK#
CK
CKE
Command
Last sync, ODT
RTT
T0
T1
T2
Ta0
Ta1
Ta2
Ta3
Ta4
Ta5
Ta6
Tb0
Tb1
Tb2
Tc0
Tc1
Tc2
Td0
Td1
tANPD
RTT
tAOFPDmin
tAOFPDmax
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
tXPDLL
PD exit transition period
NOP
NOP
NOP
NOP
NOP
NOP
ODTLoff + tAOFmin
tAOFPDmax
Sync or async, ODT
RTT
RTT
tAOFPDmin
ODTLoff + tAOFmax
ODTLoff
tAOFmax
First async, ODT
RTT
RTT
tAOFmin
TIME BREAK
TRANSITIONING
Figure 85 – Asynchronous to synchronous transition during Precharge Power Down
(with DLL frozen) exit (CL = 6; AL = CL - 1; CWL = 5; tANPD = WL - 1 = 9)
DON'T CARE
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Publication Release Date: Feb. 27, 2013
Revision A04