Datasheet

Asynchronous ODT Mode
Asynchronous ODT mode is selected when DLL is disabled by MR1 bit A0=’0’b.
In asynchronous ODT timing mode, internal ODT command is not delayed by either the Additive latency (AL)
or relative to the external ODT signal (R
TT_NOM
). In asynchronous ODT mode, the following timing parameters
apply t
AONAS,min, max
, t
AOFAS,min,max
.
Minimum R
TT_NOM
turn-on time (t
AONASmin
) is the point in time when the device termination circuit leaves
R
TT_PARK
and ODT resistance begins to change. Maximum R
TT_NOM
turn on time (t
AONASmax
) is the point in time
when the ODT resistance is reached R
TT_NOM
.
t
AONASmin
and t
AONASmax
are measured from ODT being sampled high.
Minimum R
TT_NOM
turn-off time (t
AOFASmin
) is the point in time when the devices termination circuit starts to leave
R
TT_NOM
.
Maximum R
TT_NOM
turn-off time (t
AOFASmax
) is the point in time when the on-die termination has reached R
TT_PARK
.
t
AOFASmin
and t
AOFASmax
are measured from ODT being sampled low.
T0 T1 T2 T3 T4 T5 T6 Ti Ti+1 Ti+2
Ti+3 Ti+4
Ti+5 Ti+6 Ta
TRANSITIONING DATA
Tb
t
AOFAS
(max)
t
AOFAS
(min)
t
AONAS
(min)
RTT_PARK
t
IS
t
IH
t
AONAS
(max)
RTT_NOM
t
IS
t
IH
CK#
CK
RTT
CKE
ODT
diff
Figure 170. Asynchronous ODT Timing on DDR4 SDRAM with DLL-off
AS4C256M16D4
Confidential
- 154 of 201 -
Rev.1.0 Aug.2019