EtronTech
Figure 3. State Diagram
CKEL
Initialization
Sequence
PR
Setting
MR,
EMR(1)
EMR(2)
EMR(3)
Self
Refreshing
EM68916CWQA
OCD
calibration
SRF H
CKE
(E)MRS
Idle
All banks
precharged
REF
CK
EL
CK
EH
Refreshing
ACT
EL
CK
Precharge
Power
Down
Activating
CKEL
Active
Power
Down
L
CKE
CKEL
Automatic Sequence
Cammand Sequence
CKEH
CKE
L
WR
Bank
Active
RA
RD
WR
Writing
RD
Reading
W
WR
RD
A
RD
CKEL = CKE LOW, enter Power Down
RDA
CKEH = CKE HIGH, exit Power Down,exit Self Refresh
ACT = Activate
RDA
Reading
With
Autoprecharge
WRA
A
WR
WR(A) = Write (with Autoprecharge)
RD(A) = Read (with Autoprecharge)
PR(A) = Precharge (All)
(E)MRS = (Extended) Mode Register Set
SRF = Enter Self Refresh
REF = Refresh
Writing
With
Autoprecharge
PR, PRA
PR, PRA
PR, PRA
Precharging
Note: Use caution with this diagram. It is indented to provide a floorplan of the possible state transitions and the
commands to control them, not all details. In particular situations involving more than one bank,
enabling/disabling on-die termination, Power Down entry/exit, timing restrictions during state transitions, among
other things, are not captured in full detail.
Etron Confidential
4
Rev. 1.1
Apr. 2009
ETRON [ ETRON TECHNOLOGY, INC. ]
