Internet Data Sheet
HY[B/I]25D256[16/40/80]0C[E/C/F/T](L)
256 Mbit Double-Data-Rate SDRAM
TABLE 14
Truth Table 4: Current State Bank n - Command to Bank m (different bank)
Current State
CS
RAS CAS WE Command
Action
Note
1)2)3)4)5)6)
Any
H
L
X
H
X
X
H
X
X
H
X
Deselect
NOP. Continue previous operation.
1) to 6)
No Operation NOP. Continue previous operation.
1) to 6)
Idle
X
Any
—
Command
Otherwise
Allowed to
Bank m
1) to 6)
1) to7)
Row Activating,
Active, or
Precharging
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
L
H
H
L
Active
Select and activate row
Select column and start Read burst
Select column and start Write burst
—
H
H
L
Read
1) to 7)
1) to 6)
1) to 6)
1) to 7)
1) to 6)
1) to 6)
1) to8)
L
Write
H
H
L
L
Precharge
Active
Read (Auto
Precharge Disabled)
L
H
H
L
Select and activate row
Select column and start new Read burst
—
H
L
Read
H
H
L
Precharge
Active
Write (Auto
Precharge Disabled)
L
H
H
L
Select and activate row
Select column and start Read burst
Select column and start new Write burst
—
H
H
L
Read
1) to 7)
1) to 6)
1) to 6)
1) to 7),9)
1) to 7),9),10)
1) to 6)
1) to 6)
1) to 7),9)
1) to 7),9)
1) to 6)
L
Write
H
H
L
L
Precharge
Active
Read (With Auto
Precharge)
L
H
H
L
Select and activate row
Select column and start new Read burst
Select column and start Write burst
—
H
H
L
Read
L
Write
H
H
L
L
Precharge
Active
Write (With Auto
Precharge)
L
H
H
L
Select and activate row
Select column and start Read burst
Select column and start new Write burst
—
H
H
L
Read
L
Write
H
L
Precharge
1) This table applies when CKE n-1 was HIGH and CKE n is HIGH (see Table 12: Clock Enable (CKE) and after tXSNR/tXSRD 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: 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 with Auto Precharge Enabled: See 10)
Write with Auto Precharge Enabled: See 10)
.
.
4) AUTO REFRESH and Mode Register Set 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 listed in the Command/Action column include Reads or Writes with Auto Precharge enabled and Reads or Writes with
Auto Precharge disabled.
8) Requires appropriate DM masking.
Rev. 2.3, 2007-03
20
03062006-8CCM-VPUW
QIMONDA [ QIMONDA AG ]
