128Mb: x4, x8, x16
SDRAM
This is shown in Figure 7 for CAS latencies of two and
three; data element n + 3 is either the last of a burst of four
or the last desired of a longer burst. The 128Mb SDRAM
uses a pipelined architecture and therefore does not
require the 2n rule associated with a prefetch architec-
ture. A READ command can be initiated on any clock
cycle following a previous READ command. Full-speed
random read accesses can be performed to the same
bank, as shown in Figure 8, or each subsequent READ
may be performed to a different bank.
T0
T1
T2
T3
T4
T5
T6
CLK
READ
NOP
NOP
NOP
READ
NOP
NOP
COMMAND
X = 1 cycle
BANK,
COL n
BANK,
COL b
ADDRESS
DQ
DOUT
n
DOUT
n + 1
DOUT
n + 2
DOUT
n + 3
DOUT
b
CAS Latency = 2
T0
T1
T2
T3
T4
T5
T6
T7
CLK
READ
NOP
NOP
NOP
READ
NOP
NOP
NOP
COMMAND
X = 2 cycles
BANK,
COL n
BANK,
COL b
ADDRESS
DQ
DOUT
n
DOUT
n + 1
DOUT
n + 2
DOUT
n + 3
DOUT
b
CAS Latency = 3
DON’T CARE
NOTE:
Each READ command may be to any bank. DQM is LOW.
Figure 7
Consecutive READ Bursts
128Mb: x4, x8, x16 SDRAM
128MSDRAM_E.p65 – Rev. E; Pub. 1/02
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2001, Micron Technology, Inc.
17
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