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Micron Technology, Inc., reserves the right to change products or specifications without notice.
512MbDDR2_2.fm - Rev. H 7/05 EN
43
2004, 2005 Micron Technology, Inc. All rights reserved.
512Mb: x4, x8, x16 DDR2 SDRAM
READs
Upon completion of a burst, assuming no other commands have been initiated, the DQ
will go High-Z. A detailed explanation of tDQSQ (valid data-out skew), tQH (data-out
window hold), the valid data window are depicted in Figure 29 on page 49 and Figure 30
on page 50. A detailed explanation of tDQSCK (DQS transition skew to CK) and tAC
(data-out transition skew to CK) is shown in Figure 31 on page 51.
Data from any READ burst may be concatenated with data from a subsequent READ
command to provide a continuous flow of data. The first data element from the new
burst follows the last element of a completed burst. The new READ command should be
issued x cycles after the first READ command, where x equals BL / 2 cycles. This is shown
in Figure 21.
Figure 21:
Consecutive READ Bursts
Notes: 1. DO n (or b) = data-out from column n (or column b).
2. BL = 4.
3. Three subsequent elements of data-out appear in the programmed order following DO n.
4. Three subsequent elements of data-out appear in the programmed order following DO b.
5. Shown with nominal tAC, tDQSCK, and tDQSQ.
6. Example applies only when READ commands are issued to same device.
CK
CK#
COMMAND
READ
NOP
READ
NOP
ADDRESS
Bank,
Col n
Bank,
Col b
COMMAND
READ
NOP
READ
NOP
ADDRESS
Bank,
Col n
Bank,
Col b
RL = 3
CK
CK#
COMMAND
ADDRESS
DQ
DQS, DQS#
RL = 4
DQ
DQS, DQS#
DO
n
DO
b
DO
n
DO
b
T0
T1
T2
T3
T3n
T4n
T4
T5
T6
T5n
T6n
T0
T1
T2
T3
T2n
NOP
T3n
T4n
T4
T5
T6
T5n
T6n
DON’T CARE
TRANSITIONING DATA
tCCD