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23
128Mb: x32 SDRAM
128MbSDRAMx32_D.p65 – Rev. D; Pub. 6/02
Micron Technology, Inc., reserves the right to change products or specifications without notice.
2002, Micron Technology, Inc.
128Mb: x32
SDRAM
DON’T CARE
D
IN
COMMAND
ADDRESS
WRITE
BANK,
COL
n
D
IN
n
NOP
NOP
CLK
T2
T1
T4
T3
T5
T0
CKE
INTERNAL
CLOCK
NOP
D
IN
n
+ 1
D
IN
n
+ 2
Figure 22
CLOCK SUSPEND During WRITE Burst
DON’T CARE
CLK
DQ
D
OUT
n
T2
T1
T4
T3
T6
T5
T0
COMMAND
ADDRESS
READ
NOP
NOP
NOP
BANK,
COL
n
NOP
D
OUT
n
+ 1
D
OUT
n
+ 2
D
OUT
n
+ 3
NOTE:
For this example, CAS latency = 2, burst length = 4 or greater, and
DQM is LOW.
CKE
INTERNAL
CLOCK
NOP
Figure 23
CLOCK SUSPEND During READ Burst
CLOCK SUSPEND
The clock suspend mode occurs when a column ac-
cess/burst is in progress and CKE is registered LOW. In
the clock suspend mode, the internal clock is deacti-
vated, “freezing” the synchronous logic.
For each positive clock edge on which CKE is
sampled LOW, the next internal positive clock edge is
suspended. Any command or data present on the in-
put pins at the time of a suspended internal clock edge
is ignored; any data present on the DQ pins remains
driven; and burst counters are not incremented, as
long as the clock is suspended. (See examples in Fig-
ures 22 and 23.)
Clock suspend mode is exited by registering CKE
HIGH; the internal clock and related operation will re-
sume on the subsequent positive clock edge.
BURST READ/SINGLE WRITE
The burst read/single write mode is entered by pro-
gramming the write burst mode bit (M9) in the Mode
Register to a logic 1. In this mode, all WRITE commands
result in the access of a single column location (burst of
one), regardless of the programmed burst length. READ
commands access columns according to the pro-
grammed burst length and sequence, just as in the
normal mode of operation (M9 = 0).