SDRAM
AS4SD8M16
Austin Semiconductor, Inc.
TRUTH TABLE 4: CURRENT STATE BANK n, COMMAND TO BANK m1,2,3,4,5,6
CURRENT STATE CS\ RAS\ CAS\ WE\
COMMAND (ACTION)
COMMAND INHIBIT (NOP/Continue previous operation)
NO OPERATION (NOP/Continue previous operation)
Any Command Otherwise Allowed to Bank m
ACTIVE (Select and active row)
READ (Select column and start READ burst)
WRITE (Select column and start WRITE burst)
PRECHARGE
NOTES
H
L
X
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
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 active 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 active row)
Write
(Auto Precharge
Disabled)
H
H
L
READ (Select column and start READ burst)
WRITE (Select column and start new WRITE burst)
PRECHARGE
7, 12
7, 13
9
L
H
H
L
L
L
H
H
L
ACTIVE (Select and active row)
Read
(with Auto
Precharge)
H
H
L
READ (Select column and start new READ burst)
WRITE (Select column and start WRITE burst)
PRECHARGE
7, 8, 14
7, 8, 15
9
L
H
H
L
L
H
L
L
H
H
L
ACTIVE (Select and active row)
Write
(with Auto
Precharge)
H
H
L
READ (Select column and start READ burst)
WRITE (Select column and start new WRITE burst)
PRECHARGE
7, 8, 16
7, 8, 17
9
L
NOTES:
1. This table applies when CKEn-1 was HIGH and CKEn 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 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: A READ burst has been initiated, with auto precharge disabled, and has not yet terminated or been
terminated.
Write: 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.
AS4SD8M16
(continued on next page)
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
Rev. 0.5 04/05
25
AUSTIN [ AUSTIN SEMICONDUCTOR ]
