參數(shù)資料
型號： MT47H128M8HQ-187ELAT:E
元件分類： DRAM
英文描述： 128M X 8 DDR DRAM, 0.35 ns, PBGA60
封裝： 8 X 11.50 MM, ROHS COMPLIANT, FBGA-60
文件頁數(shù)： 126/133頁
文件大?。?/td> 9170K
READ
READ bursts are initiated with a READ command. The starting column and bank ad-
dresses are provided with the READ command, and auto precharge is either enabled or
disabled for that burst access. If auto precharge is enabled, the row being accessed is
automatically precharged at the completion of the burst. If auto precharge is disabled,
the row will be left open after the completion of the burst.
During READ bursts, the valid data-out element from the starting column address will
be available READ latency (RL) clocks later. RL is defined as the sum of AL and CL:
RL = AL + CL. The value for AL and CL are programmable via the MR and EMR com-
mands, respectively. Each subsequent data-out element will be valid nominally at the
next positive or negative clock edge (at the next crossing of CK and CK#). Figure 45
(page 93) shows examples of RL based on different AL and CL settings.
DQS/DQS# is driven by the DDR2 SDRAM along with output data. The initial LOW state
on DQS and the HIGH state on DQS# are known as the read preamble (tRPRE). The
LOW state on DQS and the HIGH state on DQS# coincident with the last data-out ele-
ment are known as the read postamble (tRPST).
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), and the valid data window are depicted in Figure 54 (page 101) and Fig-
ure 55 (page 102). A detailed explanation of tDQSCK (DQS transition skew to CK) and
tAC (data-out transition skew to CK) is shown in Figure 56 (page 103).
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 (see Fig-
Nonconsecutive read data is illustrated in Figure 47 (page 95). Full-speed random
read accesses within a page (or pages) can be performed. DDR2 SDRAM supports the
use of concurrent auto precharge timing (see Table 41 (page 98)).
DDR2 SDRAM does not allow interrupting or truncating of any READ burst using BL = 4
operations. Once the BL = 4 READ command is registered, it must be allowed to com-
plete the entire READ burst. However, a READ (with auto precharge disabled) using BL
= 8 operation may be interrupted and truncated only by another READ burst as long as
the interruption occurs on a 4-bit boundary due to the 4n prefetch architecture of
DDR2 SDRAM. As shown in Figure 48 (page 96), READ burst BL = 8 operations may
not be interrupted or truncated with any other command except another READ com-
mand.
Data from any READ burst must be completed before a subsequent WRITE burst is al-
lowed. An example of a READ burst followed by a WRITE burst is shown in Figure 49
(page 96). The tDQSS (NOM) case is shown (tDQSS [MIN] and tDQSS [MAX] are de-
1Gb: x4, x8, x16 DDR2 SDRAM
READ
PDF: 09005aef821ae8bf
1GbDDR2.pdf – Rev. S 10/09 EN
92
Micron Technology, Inc. reserves the right to change products or specifications without notice.
2004 Micron Technology, Inc. All rights reserved.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MT47H128M8HQ-25AT 制造商:MICRON 制造商全稱:Micron Technology 功能描述:DDR2 SDRAM
MT47H128M8HQ-25EAT 制造商:MICRON 制造商全稱:Micron Technology 功能描述:DDR2 SDRAM
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