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參數(shù)資料
| 型號： | W3E232M16S-250STC |
| 廠商： | MICROSEMI CORP-PMG MICROELECTRONICS |
| 元件分類： | DRAM |
| 英文描述： | 64M X 16 DDR DRAM, 0.7 ns, PDSO66 |
| 封裝： | 0.400 X 0.875 INCH, 0.65 MM PITCH, TSOP2-66 |
| 文件頁數(shù)： | 2/22頁 |
| 文件大?。?/td> | 0K |
| 代理商： | W3E232M16S-250STC |
W3E232M16S-XSTX
10
White Electronic Designs Corporation (602) 437-1520 www.wedc.com
White Electronic Designs
December 2005
Rev. 1
White Electronic Designs Corp. reserves the right to change products or specications without notice.
PRELIMINARY*
TRUTH TABLE – DM OPERATION
NAME (FUNCTION)
DM
DQs
WRITE ENABLE (10)
L
Valid
WRITE INHIBIT (10)
H
X
during an AUTO REFRESH command. Each DDR SDRAM
requires AUTO REFRESH cycles at an average interval
of 7.8125s (maximum).
To allow for improved efficiency in scheduling and
switching between tasks, some exibility in the absolute
refresh interval is provided. A maximum of eight AUTO
REFRESH commands can be posted to any given DDR
SDRAM, meaning that the maximum absolute interval
between any AUTO REFRESH command and the next
AUTO REFRESH command is 9 x 7.8125s (70.3s). This
maximum absolute interval is to allow future support for
DLL updates internal to the DDR SDRAM to be restricted
to AUTO REFRESH cycles, without allowing excessive
drift in tAC between updates.
Although not a JEDEC requirement, to provide for future
functionality features, CKE must be active (High) during
the AUTO REFRESH period. The AUTO REFRESH period
begins when the AUTO REFRESH command is registered
and ends tRFC later.
SELF REFRESH
The SELF REFRESH command can be used to retain
data in the DDR SDRAM, even if the rest of the system is
powered down. When in the self refresh mode, the DDR
SDRAM retains data without external clocking. The SELF
REFRESH command is initiated like an AUTO REFRESH
command except CKE is disabled (LOW). The DLL is
automatically disabled upon entering SELF REFRESH and
is automatically enabled upon exiting SELF REFRESH (A
DLL reset and 200 clock cycles must then occur before a
READ command can be issued). Input signals except CKE
are “Don’t Care” during SELF REFRESH. VREF voltage is
also required for the full duration of SELF REFRESH.
The procedure for exiting self refresh requires a sequence
of commands. First, CK and CK# must be stable prior
to CKE going back HIGH. Once CKE is HIGH, the DDR
SDRAM must have NOP commands issued for tXSNR,
because time is required for the completion of any internal
refresh in progress.
A simple algorithm for meeting both refresh and DLL
requirements is to apply NOPs for tXSNR time, then a DLL
Reset and NOPs for 200 additional clock cycles before
applying any other command.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| W3E232M16S-250STCG | 制造商:WEDC 制造商全稱:White Electronic Designs Corporation 功能描述:2x32Mx16bit DDR SDRAM |
| W3E232M16S-250STI | 制造商:WEDC 制造商全稱:White Electronic Designs Corporation 功能描述:2x32Mx16bit DDR SDRAM |
| W3E232M16S-250STIG | 制造商:WEDC 制造商全稱:White Electronic Designs Corporation 功能描述:2x32Mx16bit DDR SDRAM |
| W3E232M16S-266STC | 制造商:WEDC 制造商全稱:White Electronic Designs Corporation 功能描述:2x32Mx16bit DDR SDRAM |
| W3E232M16S-266STCG | 制造商:WEDC 制造商全稱:White Electronic Designs Corporation 功能描述:2x32Mx16bit DDR SDRAM |
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