SDRAM
AS4SD4M16
Austin Semiconductor, Inc.
TRUTH TABLE 4 - CURRENT STATE BANK n - COMMAND TO BANK m
(Notes: 1-6; notes appear below and on next page)
COMMAND/ACTION
CURRENT STATE
CS\
H
L
X
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
RAS\ CAS\ WE\
NOTES
COMMAND INHIBIT (NOP/continue previous operation)
NO OPERATION (NOP/continue previous operation)
Any command otherwise allowed to bank m
ACTIVE (select and activate row)
READ (select column and start READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE
X
H
X
L
H
H
L
X
H
X
H
L
X
H
X
H
H
L
Any
Idle
Row Activating,
Active or
Precharging
7
7
L
H
H
L
L
L
H
H
L
ACTIVE (select and activate row)
Read
(Auto-
Precharge Disabled)
H
H
L
READ (select column and start new READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE
7, 10
7, 11
9
L
H
H
L
L
L
H
H
L
ACTIVE (select and activate row)
Write
(Auto-
Precharge Disabled)
H
H
L
7, 1
7, 13
9
READ (select column and start READ burst)
WRITE (select column and start new WRITE burst)
PRECHARGE
L
H
H
L
L
L
H
H
L
ACTIVE (select and activate row)
Read
(with Auto-
Precharge)
H
H
L
7, 8 ,14
7, 8 15
9
READ (select column and start new READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE
L
H
H
L
L
L
H
H
L
ACTIVE (select and activate row)
Write
(with Auto-
Precharge)
H
H
L
7, 8 16
7, 8 17
9
READ (select column and start READ burst)
WRITE (select column and start new WRITE burst)
PRECHARGE
L
H
L
NOTE:
1. This table applies when CKE n-1 was HIGH and CKE n is HIGH (see Truth Table 2) and after tXSR has been met (if the previous state
was self refresh).
2. This table describes alternate bank operation, except where noted; i.e., the current state is for bank n and the commands shown are
those allowed to be issued to bank m (assuming that bank m is in such a state that the given command is allowable). Exceptions are
covered in the notes below.
3. Current state definitions:
Idle:
The bank has been precharged, and tRP has been met.
Row Active:
A row in the bank has been activated, and tRCD has been met. No data bursts/ accesses and no register
accesses are in progress.
Read:
Write:
A READ burst has been initiated, with AUTO PRECHARGE disabled, and has not yet terminated or been
terminated.
A WRITE burst has been initiated, with AUTO PRECHARGE disabled, and has not yet terminated or been
terminated.
Read w/Auto-
Precharge Enabled:
Starts with registration of a READ command with AUTO PRECHARGE enabled, and ends when tRP has
been met. Once tRP is met, the bank will be in the idle state.
Write w/Auto-
Precharge Enabled:
Starts with registration of a WRITE command with AUTO PRECHARGE enabled, and ends when tRP has
been met. Once tRP is met, the bank will be in the idle state.
4. AUTO REFRESH, SELF REFRESH and LOAD MODE REGISTER commands may only be issued when all banks are idle.
5. A BURST TERMINATE command cannot be issued to another bank; it applies to the bank represented by the current state only.
6. All states and sequences not shown are illegal or reserved.
7. READs or WRITEs to bank m listed in the Command (Action) column include READs or WRITEs with AUTO PRECHARGE
enabled and READs or WRITEs with AUTO PRECHARGE disabled.
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
AS4SD4M16
Rev. 2.1 6/05
28
AUSTIN [ AUSTIN SEMICONDUCTOR ]
