AS4C256M16D3
Table 26. Latencies and timing parameters relevant for Dynamic ODT
Name and
Description
ODT turn-on
Latency
ODT turn-off
Latency
ODT Latency for
changing from
RTT_Nom to
RTT_WR
ODT Latency for
change from
RTT_WR to
RTT_Nom (BL=4)
ODT Latency for
change from
RTT_WR to
RTT_Nom (BL=8)
Minimum ODT high
time
Definition for all DDR3
Abbr.
Defined from
Defined to
Unit
tCK
tCK
speed pin
registering external
ODT signal high
registering external
ODT signal low
turning
termination on
turning
ODTLon
ODTLoff
ODTLon=WL-2
ODTLoff=WL-2
ODTLcnw=WL-2
termination off
change RTT
strength from
RTT_Nom to
RTT_WR
change RTT
strength from
RTT_WR to
RTT_Nom
change RTT
strength from
RTT_WR to
RTT_Nom
registering external
write command
ODTLcnw
ODTLcwn4
ODTLcwn8
tCK
tCK
registering external
write command
ODTLcwn4=4+ODTLoff
ODTLcwn8=6+ODTLoff
registering external
write command
tCK (avg)
ODT registered
low
ODTH4 registering ODT high
ODTH4=4
ODTH4=4
ODTH8=6
tCK (avg)
tCK (avg)
after ODT assertion
Minimum ODT
high time
after Write (BL=4)
Minimum ODT
high time
registering write with
ODT high
ODT registered
low
ODTH4
registering write with
ODT high
ODT register
low
ODTH8
tCK (avg)
tCK (avg)
after Write (BL=8)
ODTLcnw
tADC
tADC(min)=0.3tCK(avg)
tADC(max)=0.7tCK(avg)
RTT change skew
RTT valid
ODTLcwn
Note 1:
tAOF,nom and tADC,nom are 0.5tCK (effectively adding half a clock cycle to ODTLoff, ODTcnw, and ODTLcwn)
Asynchronous ODT Mode
Asynchronous ODT mode is selected when DRAM runs in DLLon mode, but DLL is temporarily disabled (i.e.
frozen) in precharge power-down (by MR0 bit A12). Based on the power down mode definitions, this is currently
Precharge power down mode if DLL is disabled during precharge power down by MR0 bit A12.
In asynchronous ODT timing mode, internal ODT command is NOT delayed by Additive Latency (AL) relative to
the external ODT command.
In asynchronous ODT mode, the following timing parameters apply: tAONPD min/max, tAOFPD min/max.
Minimum RTT turn-on time (tAONPD min) is the point in time when the device termination circuit leaves high
impedance state and ODT resistance begins to turn on. Maximum RTT turn on time (tAONPD max) is the point
in time when the ODT resistance is fully on.
tAONPDmin and tAONPDmax are measured from ODT being sampled high.
Minimum RTT turn-off time (tAOFPDmin) is the point in time when the devices termination circuit starts to turn
off the ODT resistance. Maximum ODT turn off time (tAOFPDmax) is the point in time when the on-die
termination has reached high impedance. tAOFPDmin and tAOFPDmax are measured from ODT being sample
low.
Table 27. ODT timing parameters for Power Down (with DLL frozen) entry and exit
Description
Min
Max
ODT to RTT
turn-on delay
min{ ODTLon * tCK + tAONmin; tAONPDmin } max{ ODTLon * tCK + tAONmax; tAONPDmax }
min{ (WL - 2) * tCK + tAONmin; tAONPDmin } max{ (WL - 2) * tCK + tAONmax; tAONPFmax }
ODT to RTT
turn-off delay
min{ ODTLoff * tCK + tAOFmin; tAOFPDmin } max{ ODTLoff * tCK + tAOFmax; tAOFPDmax }
min{ (WL - 2) * tCK + tAOFmin; tAOFPDmin } max{ (WL - 2) * tCK + tAOFmax; tAOFPDmax }
tANPD
WL - 1
Confidential
51
Rev. 3.0
Aug. /2014
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
