Austin Semiconductor, Inc.
COMMANDS
Table 4 and Table 5 provide a quick reference of available
commands. This is followed by a verbal description of each
command. Two additional Truth Tables, Table 7 and Table8
appear following the Operation section, provide current state/
next state information.
COTS
COTS PEM
SDRAM
AS4DDR32M16
TABLE 4: TRUTH TABLE - COMMANDS (Note 1 applies to all commands)
FUNCTION
DESELECT (NOP)
NO OPERATION (NOP)
ACTIVE (Select bank and activate row)
READ (Select bank and column, and start READ burst)
WRITE (Select bank and column, and start WRITE burst)
BURST TERMINATE
PRECHARGE (Deactivate row in bank or banks)
AUTO REFRESH or SELF REFRESH (Enter self refresh mode)
LOAD MODE REGISTER
CS#
H
L
L
L
L
L
L
L
L
RAS#
X
H
L
H
H
H
L
L
L
CAS#
X
H
H
L
L
H
H
L
L
WE#
X
H
H
H
L
L
L
H
L
ADDR NOTES
X
9
X
9
Bank/Row
3
Bank/Col
4
Bank/Col
4
X
8
Code
5
X
6, 7
Op-Code
2
NOTES:
1. CKE is HIGH for all commands shown except SELF REFRESH.
2. BA0-BA1 select either the mode register or the extended mode register (BA0 = 0, BA1 = 0 select the mode register; BA0 = 1, BA1 = 0 select
extended mode register; other combinations of BA0-BA1 are reserved). A0-A12 provide the opcode to be written to the selected mode
register.
3. BA0-BA1 provide bank address and A0-A12 provide row address.
4. BA0-BA1 provide bank address; A0-A9 provide column address.
A10 HIGH enables the auto precharge feature (non persistent), and A10 LOW disables the auto precharge feature.
5. A10 LOW: BA0-BA1 determine which bank is precharged. A10 HIGH: all banks are precharged and BA0-BA1 are “Don’t Care.”
6. This command is AUTO REFRESH if CKE is HIGH, SELF REFRESH if CKE is LOW.
7. Internal refresh counter controls row addressing; for within the Self Refresh mode all inputs and I/Os are “Don’t Care” except for CKE.
8. Applies only to read bursts with auto precharge disabled; this command is undefined (and should not be used) for read bursts with auto
precharge enabled and for write bursts.
9. DESELECT and NOP are functionally interchangeable.
TABLE 5: TRUTH TABLE - DM OPERATION
(Note 1 applies to all commands)
FUNCTION
Write Enable
Write Inhibit
DM
L
H
DQ
Valid
X
NOTE:
1. Used to mask write data; provided coincident with the corresponding data.
AS4DDR32M16
Rev. 1.5 06/06
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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