64Mb: x32
SDRAM
operation that would result from the same fixed-length
burst with auto precharge. The disadvantage of the
PRECHARGE command is that it requires that the com-
mand and address buses be available at the appropri-
ate time to issue the command; the advantage of the
PRECHARGE command is that it can be used to trun-
cate fixed-length or full-page bursts.
bursts may be truncated with a BURST TERMINATE
command, provided that auto precharge was not acti-
vated. The BURST TERMINATE command should be
issued x cycles before the clock edge at which the last
desired data element is valid, where x equals the CAS
latency minus one. This is shown in Figure 12 for each
possible CAS latency; data element n + 3 is the last
desired data element of a longer burst.
Full-page READ bursts can be truncated with the
BURST TERMINATE command, and fixed-length READ
Figure 12
Terminating a READ Burst
T0
T1
T2
T3
T4
T5
T6
CLK
BURST
TERMINATE
READ
NOP
NOP
NOP
NOP
NOP
COMMAND
ADDRESS
DQ
X = 0 cycles
BANK,
COL n
D
OUT
D
n + 1
OUT
D
n + 2
OUT
DOUT
n
n + 3
CAS Latency = 1
T0
T1
T2
T3
T4
T5
T6
CLK
BURST
TERMINATE
READ
NOP
NOP
NOP
NOP
NOP
COMMAND
ADDRESS
DQ
X = 1 cycle
BANK,
COL n
D
OUT
D
n + 1
OUT
DOUT
D
n + 3
OUT
n
n + 2
CAS Latency = 2
T0
T1
T2
T3
T4
T5
T6
T7
CLK
COMMAND
ADDRESS
DQ
BURST
TERMINATE
READ
NOP
NOP
NOP
NOP
NOP
NOP
X = 2 cycles
BANK,
COL n
D
OUT
D
OUT
D
n + 2
OUT
D
n + 3
OUT
n
n + 1
CAS Latency = 3
NOTE: DQM is LOW.
DON’T CARE
64Mb: x32 SDRAM
64MSDRAMx32_5.p65 – Rev. B; Pub. 6/02
MicronTechnology,Inc.,reservestherighttochangeproductsorspecificationswithoutnotice.
©2002,MicronTechnology,Inc.
18
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