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MT48LC2M32B2TG 参数 Datasheet PDF下载

MT48LC2M32B2TG图片预览
型号: MT48LC2M32B2TG
PDF下载: 下载PDF文件 查看货源
内容描述: 同步DRAM [SYNCHRONOUS DRAM]
分类和应用: 动态存储器
文件页数/大小: 53 页 / 1810 K
品牌: MICRON [ MICRON TECHNOLOGY ]
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64Mb: x32  
SDRAM  
Data for any WRITE burst may be truncated with a  
subsequent READ command, and data for a fixed-  
length WRITE burst may be immediately followed by a  
READ command. Once the READ command is regis-  
tered, the data inputs will be ignored, and WRITEs will  
not be executed. An example is shown in Figure 17.  
Data n + 1 is either the last of a burst of two or the last  
desired of a longer burst.  
Data for a fixed-length WRITE burst may be fol-  
lowed by, or truncated with, a PRECHARGE command  
to the same bank (provided that auto precharge was  
not activated), and a full-page WRITE burst may be  
truncated with a PRECHARGE command to the same  
bank. The PRECHARGE command should be issued  
tWR after the clock edge at which the last desired input  
data element is registered. The “two-clock” write-back  
requires at least one clock plus time, regardless of fre-  
quency, in auto precharge mode. In addition, when  
truncating a WRITE burst, the DQM signal must be  
used to mask input data for the clock edge prior to, and  
the clock edge coincident with, the PRECHARGE com-  
mand. An example is shown in Figure 18. Data n + 1 is  
either the last of a burst of two or the last desired of a  
longer burst. Following the PRECHARGE command, a  
subsequent command to the same bank cannot be  
t
issued until RP is met. The precharge will actually be-  
gin coincident with the clock-edge (T2 in Figure 18) on  
t
a “one-clock” WR and sometime between the first and  
second clock on a “two-clock” tWR (between T2 and T3  
in Figure 18.)  
In the case of a fixed-length burst being executed to  
completion, a PRECHARGE command issued at the  
optimum time (as described above) provides the same  
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.  
Figure 16  
Random WRITE Cycles  
T0  
T1  
T2  
T3  
CLK  
WRITE  
WRITE  
WRITE  
WRITE  
COMMAND  
ADDRESS  
DQ  
Figure 18  
WRITE to PRECHARGE  
BANK,  
COL n  
BANK,  
COL a  
BANK,  
COL x  
BANK,  
COL m  
T0  
T1  
T2  
T3  
T4  
T5  
T6  
D
IN  
D
IN  
D
IN  
DIN  
x
CLK  
m
n
a
t
t
t
WR = 1 CLK ( CK > WR)  
DON’T CARE  
DQM  
NOTE: Each WRITE command may be to any bank. DQM is LOW.  
t
RP  
NOP  
NOP  
NOP  
WRITE  
NOP  
PRECHARGE  
ACTIVE  
COMMAND  
ADDRESS  
BANK  
(a or all)  
BANK a,  
COL n  
BANK a,  
ROW  
Figure 17  
t
WR  
WRITE to READ  
D
n
IN  
DIN  
n + 1  
DQ  
T0  
T1  
T2  
T3  
T4  
T5  
t
t
t
CLK  
WR = 2 CLK (when WR > CK)  
DQM  
WRITE  
NOP  
READ  
NOP  
NOP  
NOP  
COMMAND  
ADDRESS  
DQ  
t
RP  
NOP  
NOP  
WRITE  
NOP  
NOP  
PRECHARGE  
ACTIVE  
COMMAND  
ADDRESS  
BANK,  
COL n  
BANK,  
COL b  
BANK  
(a or all)  
BANK a,  
COL n  
BANK a,  
ROW  
t
WR  
DIN  
n
DIN  
n + 1  
DOUT  
b
DOUT  
b + 1  
D
IN  
DIN  
n + 1  
DQ  
n
DON’T CARE  
NOTE:  
DQM could remain LOW in this example if the WRITE burst is a fixed  
length of two.  
DON’T CARE  
64Mb: x32 SDRAM  
64MSDRAMx32_5.p65 – Rev. B; Pub. 6/02  
MicronTechnology,Inc.,reservestherighttochangeproductsorspecificationswithoutnotice.  
©2002,MicronTechnology,Inc.  
20  
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