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| 型号： | W9725G6JB25I |
| 厂商： | Winbond Electronics |
| 文件页数： | 22/87页 |
| 文件大小： | 0K |
| 描述： | IC DDR2 SDRAM 256MBIT 84WBGA |
| 标准包装： | 200 |
| 格式 - 存储器： | RAM |
| 存储器类型： | DDR2 SDRAM |
| 存储容量： | 256M（16Mx16） |
| 速度： | 2.5ns |
| 接口： | 并联 |
| 电源电压： | 1.7 V ~ 1.9 V |
| 工作温度： | -40°C ~ 95°C |
| 封装/外壳： | 84-TFBGA |
| 供应商设备封装： | 84-WBGA（8x12.5） |
| 包装： | 托盘 |
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W9725G6JB
7.3.8
Self Refresh Exit Command
(CKE = "H", CS = "H" or CKE = "H", CS = "L", RAS = "H", CAS = "H", WE = "H", BA0, BA1,
A0 to A12 = Don ? t Care)
The procedure for exiting Self Refresh requires a sequence of commands. First, the clock must be
stable prior to CKE going back HIGH. Once Self Refresh Exit is registered, a delay of at least t XSNR
must be satisfied before a valid command can be issued to the device to allow for any internal refresh
in progress. CKE must remain HIGH for the entire Self Refresh exit period t XSRD for proper operation
except for self refresh re-entry.
Upon exit from Self Refresh, the DDR2 SDRAM can be put back into Self Refresh mode after waiting
at least t XSNR period and issuing one refresh command (refresh period of t RFC ). NOP or Deselect
commands must be registered on each positive clock edge during the Self Refresh exit interval t XSNR .
ODT should be turned off during t XSRD .
The use of Self Refresh mode introduces the possibility that an internally timed refresh event can be
missed when CKE is raised for exit from Self Refresh mode. Upon exit from Self Refresh, the DDR2
SDRAM requires a minimum of one extra auto refresh command before it is put back into Self Refresh
mode.
7.3.9
Refresh Command
( CS = "L", RAS = "L", CAS = "L", WE = "H", CKE = "H", BA0, BA1, A0 to A12 = Don?t Care)
Refresh is used during normal operation of the DDR2 SDRAM. This command is non persistent, so it
must be issued each time a refresh is required.
The refresh addressing is generated by the internal refresh controller. This makes the address bits
“Don?t Care” during an Auto Refresh command. The DDR2 SDRAM requires Auto Refresh cycles at
an average periodic interval of t REFI (max.) .
When the refresh cycle has completed, all banks of the DDR2 SDRAM will be in the precharged (idle)
state. A delay between the auto refresh command (REF) and the next activate command or
subsequent auto refresh command must be greater than or equal to the auto refresh cycle time (t RFC ).
To allow for improved efficiency in scheduling and switching between tasks, some flexibility in the
absolute refresh interval is provided. A maximum of eight Refresh commands can be posted to any
given DDR2 SDRAM, meaning that the maximum absolute interval between any Refresh command
and the next Refresh command is 9 x t REFI .
T0
T1
T2
T3
Tm
Tn
Tn + 1
CLK/CLK
"HIGH"
CKE
≥ t RP
≥ t RFC
≥ t RFC
CMD
Precharge
NOP
NOP
REF
REF
NOP
ANY
Figure 13 – Refresh command
Publication Release Date: Nov. 29, 2011
- 22 -
Revision A02
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相关代理商/技术参数 |
参数描述 |
|---|---|
| W9725G6KB-18 | 制造商:Winbond Electronics 功能描述:IC MEMORY 制造商:Winbond Electronics Corp 功能描述:IC MEMORY |
| W9725G6KB-25 | 功能描述:IC DDR2 SDRAM 256MBIT 84WBGA RoHS:是 类别:集成电路 (IC) >> 存储器 系列:- 标准包装:1 系列:- 格式 - 存储器:闪存 存储器类型:闪存 - NAND 存储容量:4G（256M x 16） 速度:- 接口:并联 电源电压:2.7 V ~ 3.6 V 工作温度:0°C ~ 70°C 封装/外壳:48-TFSOP（0.724"，18.40mm 宽） 供应商设备封装:48-TSOP I 包装:Digi-Reel® 其它名称:557-1461-6 |
| W9725G6KB-25 TR | 制造商:Winbond Electronics Corp 功能描述:256M DDR2-800, X16 |
| W9725G6KB25A | 制造商:WINBOND 制造商全称:Winbond 功能描述:DLL aligns DQ and DQS transitions with clock, Data masks (DM) for write data, Write Data Mask |
| W9725G6KB25I | 制造商:Winbond Electronics Corp 功能描述:DRAM Chip DDR2 SDRAM 256M-Bit 16Mx16 1.8V 84-Pin WBGA 制造商:Winbond Electronics 功能描述:IC DDR2 SDRAM 256M 2.5NS 84WBGA 制造商:Winbond Electronics Corp 功能描述:IC DDR2 SDRAM 256M 2.5NS 84WBGA 制造商:Winbond 功能描述:DRAM Chip DDR2 SDRAM 256M-Bit 16Mx16 1.8V 84-Pin WBGA |
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