Datasheet

Operation Mode
The following tables provide a quick reference of available DDR2 SDRAM commands, including CKE power-down
modes and bank-to-bank command.
Table 4. Truth Table (Note (1), (2))
Command
State
CKE
n-1
CKE
n
DM
BA0-2
A10
A0-9, 11-12
CS#
RAS#
CAS#
WE#
BankActivate
Idle
(3)
H
H
X
V
Row address
L
L
H
H
Single Bank Precharge
Any
H
H
X
V
L
X
L
L
H
L
All Banks Precharge
Any
H
H
X
X
H
X
L
L
H
L
Write
Active
(3)
H
H
X
V
L
Column
address
(A0 – A9)
L
H
L
L
Write with AutoPrecharge
Active
(3)
H
H
X
V
H
L
H
L
L
Read
Active
(3)
H
H
X
V
L
Column
address
(A0 – A9)
L
H
L
H
Read and Autoprecharge
Active
(3)
H
H
X
V
H
L
H
L
H
(Extended) Mode Register Set
Idle
H
H
X
V
OP code
L
L
L
L
No-Operation
Any
H
X
X
X
X
X
L
H
H
H
Device Deselect
Any
H
X
X
X
X
X
H
X
X
X
Refresh
Idle
H
H
X
X
X
X
L
L
L
H
SelfRefresh Entry
Idle
H
L
X
X
X
X
L
L
L
H
SelfRefresh Exit
Idle
L
H
X
X
X
X
H
X
X
X
L
H
H
H
Power Down Mode Entry
Idle
H
L
X
X
X
X
H
X
X
X
L
H
H
H
Power Down Mode Exit
Any
L
H
X
X
X
X
H
X
X
X
L
H
H
H
Data Input Mask Disable
Active
H
X
L
X
X
X
X
X
X
X
Data Input Mask Enable
(4)
Active
H
X
H
X
X
X
X
X
X
X
NOTE 1: V=Valid data, X=Don't Care, L=Low level, H=High level
NOTE 2: CKEn signal is input level when commands are provided.
CKEn
-1
signal is input level one clock cycle before the commands are provided.
NOTE 3: These are states of bank designated by BA signal.
NOTE 4: LDM and UDM can be enabled respectively.
AS4C64M16D2A-25BIN
AS4C64M16D2A-25BCN
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Rev.1.1 October 2017