PRELIMINARY
1Gb: x4, x8, x16
DDR SDRAM
Table 7:
CURRENT
STATE
Any
Truth Table – Current State Bank
n
- Command to Bank
n
(Notes: 1-6; notes appear below and on next page)
CS#
H
L
Idle
L
L
L
L
L
L
L
L
L
L
L
L
L
RAS# CAS#
X
H
L
L
L
H
H
L
H
H
L
H
H
H
L
X
H
H
L
L
L
L
H
L
L
H
H
L
L
H
WE#
X
H
H
H
L
H
L
L
H
L
L
L
H
L
L
COMMAND/ACTION
DESELECT (NOP/continue previous operation)
NO OPERATION (NOP/continue previous operation)
ACTIVE (select and activate row)
AUTO REFRESH
LOAD MODE REGISTER
READ (select column and start READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE (deactivate row in bank or banks)
READ (select column and start new READ burst)
WRITE (select column and start WRITE burst)
PRECHARGE (truncate READ burst, start PRECHARGE)
BURST TERMINATE
READ (select column and start READ burst)
WRITE (select column and start new WRITE burst)
PRECHARGE (truncate WRITE burst, start PRECHARGE)
7
7
10
10
8
10
10, 12
8
9
10, 11
10
8, 11
NOTES
Row
Active
Read
(Auto-
Precharge
Disabled)
Write
(Auto-
Precharge
Disabled)
NOTE:
1. This table applies when CKE
n-1
was HIGH and CKE
n
is HIGH (see Table 6 on page 40) and after
t
XSNR has been met (if
the previous state was self refresh).
2. This table is bank-specific, except where noted (i.e., the current state is for a specific bank and the commands shown are those
allowed to be issued to that bank when in that state). Exceptions are covered in the notes below.
3. Current state definitions:
Idle:The bank has been precharged, and
t
RP has been met.
Row Active: A row in the bank has been activated, and
t
RCD has been met. No data bursts/accesses and no regis-
ter accesses are in progress.
Read: A READ burst has been initiated, with auto precharge disabled, and has not yet terminated or been termi-
nated.
Write: A WRITE burst has been initiated, with auto precharge disabled, and has not yet terminated or been ter-
minated.
4. The following states must not be interrupted by a command issued to the same bank. COMMAND INHIBIT or NOP commands, or
allowable commands to the other bank should be issued on any clock edge occurring during these states. Allowable commands
to the other bank are determined by its current state and Table 7, Truth Table – Current State Bank n - Command to Bank n, on
Precharging: Starts with registration of a PRECHARGE command and ends when
t
RP is met. Once
t
RP is met, the
bank will be in the idle state.
Row Activating: Starts with registration of an ACTIVE command and ends when
t
RCD is met. Once
t
RCD is met,
the bank will be in the “row active” state.
Read w/Auto-
Precharge Enabled: Starts with registration of a READ command with auto precharge enabled and ends when
t
RP has been met. Once
t
RP is met, the bank will be in the idle state.
09005aef8076894f
1gbDDRx4x8x16_2.fm - Rev. A 3/03 EN
41
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2003 Micron Technology. Inc.
MICRON [ MICRON TECHNOLOGY ]
