EDS1232AHTA
Command Operation
Command Truth Table
The SDRAM recognizes the following commands specified by the /CS, /RAS, /CAS, /WE and address pins.
CKE
Function
Device deselect
No operation
Burst stop
Read
Read with auto precharge
Write
Write with auto precharge
Bank activate
Precharge select bank
Precharge all banks
Mode register set
Symbol
DESL
NOP
BST
READ
READA
WRIT
WRITA
ACT
PRE
PALL
MRS
n–1
H
H
H
H
H
H
H
H
H
H
H
n
×
×
×
×
×
×
×
×
×
×
×
/CS
H
L
L
L
L
L
L
L
L
L
L
/RAS
×
H
H
H
H
H
H
L
L
L
L
/CAS
×
H
H
L
L
L
L
H
H
H
L
/WE
×
H
L
H
H
L
L
H
L
L
L
BA1
×
×
×
V
V
V
V
V
V
×
L
BA0
×
×
×
V
V
V
V
V
V
×
L
A10
×
×
×
L
H
L
H
V
L
H
L
A0 to
A11
×
×
×
V
V
V
V
V
×
×
V
Remark: H: VIH. L: VIL.
×:
VIH or VIL. V: Valid address input.
Device deselect command [DESL]
When this command is set (/CS is High), the SDRAM ignore command input at the clock. However, the internal
status is held.
No operation [NOP]
This command is not an execution command. However, the internal operations continue.
Burst stop command [BST]
This command can stop the current burst operation.
Column address strobe and read command [READ]
This command starts a read operation. In addition, the start address of burst read is determined by the column
address (see Address Pins Table in Pin Function) and the bank select address (BA0, BA1). After the read operation,
the output buffer becomes High-Z.
Read with auto-precharge [READA]
This command automatically performs a precharge operation after a burst read with a burst length of 1, 2, 4 or 8.
Column address strobe and write command [WRIT]
This command starts a write operation. When the burst write mode is selected, the column address (see Address
Pins Table in Pin Function) and the bank select address (BA0, BA1) become the burst write start address. When the
single write mode is selected, data is only written to the location specified by the column address (see Address Pins
Table in Pin Function) and the bank select address (BA0, BA1).
Write with auto-precharge [WRITA]
This command automatically performs a precharge operation after a burst write with a length of 1, 2, 4 or 8, or after a
single write operation.
Data Sheet E1163E30 (Ver. 3.0)
13
ELPIDA [ ELPIDA MEMORY ]
