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| 型号： | W9725G6KB-25I |
| 厂商： | Winbond Electronics |
| 文件页数： | 28/87页 |
| 文件大小： | 0K |
| 描述： | IC DDR2 SDRAM 256MBIT 84WBGA |
| 标准包装： | 209 |
| 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： | * |
| 其它名称： | Q7118748 |
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W9725G6KB
Auto-precharge is also implemented during Write commands. The precharge operation engaged by
the Auto-precharge command will not begin until the last data of the burst write sequence is properly
stored in the memory array.
This feature allows the precharge operation to be partially or completely hidden during burst read
cycles (dependent upon CAS Latency) thus improving system performance for random data access.
The RAS lockout circuit internally delays the Precharge operation until the array restore operation
has been completed (t RAS satisfied) so that the Auto-precharge command may be issued with any
read or write command.
8.7.1
Burst read with Auto-precharge
If A10 is HIGH when a Read Command is issued, the Read with Auto-precharge function is engaged.
The DDR2 SDRAM starts an Auto-precharge operation on the rising edge which is (AL + BL/2) cycles
later from the Read with AP command if t RAS (min) and t RTP (min) are satisfied. (Example timing
waveform refer to 11.22 Burst read operation with Auto-precharge diagram in Chapter 11)
If t RAS (min) is not satisfied at the edge, the start point of Auto-precharge operation will be delayed until
t RAS (min) is satisfied.
If t RTP (min) is not satisfied at the edge, the start point of Auto-precharge operation will be delayed until
t RTP (min) is satisfied.
In case the internal precharge is pushed out by t RTP , t RP starts at the point where t RTP ends (not at the
next rising clock edge after this event). So for BL = 4 the minimum time from Read with Auto-
precharge to the next Activate command becomes AL + RU{ (t RTP + t RP ) / t CK(avg) } (Example timing
waveform refer to 11.23 Burst read operation with Auto-precharge diagram in Chapter 11.) , for BL = 8
the time from Read with Auto-precharge to the next Activate command is AL + 2 + RU{ (t RTP + t RP ) /
t CK(avg) }, where RU stands for “rounded up to the next integer”. In any event internal precharge does
not start earlier than two clocks after the last 4-bit prefetch.
A new bank active command may be issued to the same bank if the following two conditions are
satisfied simultaneously.
?
?
The RAS precharge time (t RP ) has been satisfied from the clock at which the Auto-precharge
begins.
The RAS cycle time (t RC ) from the previous bank activation has been satisfied.
(Example timing waveforms refer to 11.24 to 11.25 Burst read with Auto-precharge followed by an
activation to the same bank (t RC Limit) and (t RP Limit) diagram in Chapter 11)
8.7.2
Burst write with Auto-precharge
If A10 is HIGH when a Write Command is issued, the Write with Auto-Precharge function is engaged.
The DDR2 SDRAM automatically begins precharge operation after the completion of the burst write
plus write recovery time (WR) programmed in the mode register. The bank undergoing Auto-
precharge from the completion of the write burst may be reactivated if the following two conditions are
satisfied.
?
?
The data-in to bank activate delay time (WR + t RP ) has been satisfied.
The RAS cycle time (t RC ) from the previous bank activation has been satisfied.
(Example timing waveforms refer to 11.26 to 11.27 Burst write with Auto-precharge (t RC Limit) and
(WR + t RP Limit) diagram in Chapter 11)
Publication Release Date: Sep. 03, 2012
- 28 -
Revision A03
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相关代理商/技术参数 |
参数描述 |
|---|---|
| W9725G6KB25I TR | 制造商:Winbond Electronics Corp 功能描述:256M DDR2-800, X16, IND TEMP |
| W9725G6KB25K | 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 |
| W9725G6KB-3 | 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 |
| W9725G8JB | 制造商:WINBOND 制造商全称:Winbond 功能描述:8M ? 4 BANKS ? 8 BIT DDR2 SDRAM |
| W9725G8JB25 | 制造商:Winbond Electronics Corp 功能描述:DRAM Chip DDR2 SDRAM 256M-Bit 32Mx8 1.8V 60-Pin WBGA |
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