- 您现在的位置：买卖IC网 > PDF目录370033 > 256MBDDRSDRAM (SAMSUNG SEMICONDUCTOR CO. LTD.) DDR SDRAM Specification Version 0.3 PDF资料下载
参数资料
| 型号： | 256MBDDRSDRAM |
| 厂商： | SAMSUNG SEMICONDUCTOR CO. LTD. |
| 英文描述： | DDR SDRAM Specification Version 0.3 |
| 中文描述： | DDR SDRAM的规格版本0.3 |
| 文件页数： | 22/51页 |
| 文件大小： | 658K |
| 代理商： | 256MBDDRSDRAM |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页当前第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页第49页第50页第51页
- 22 -
REV. 0.3 November 2. 2000
256Mb DDR SDRAM
Preliminary
3.3.5 Read Interrupted by a Precharge
A Burst Read operation can be interrupted by precharge of the same bank. The minimum 1 clock is required
for the read to precharge intervals. A precharge command to output disable latency is equivalent to the CAS
latency.
Command
< Burst Length=8, CAS Latency=2 >
READ
NOP
Precharge
NOP
NOP
NOP
NOP
NOP
NOP
DQS
DQ
′
s
CAS Latency=2
Dout 0
Dout 1
Dout 2
Dout 3
Interrupted by precharge
2
0
1
5
3
4
8
6
7
Dout 4
Dout 5 Dout 6
Dout 7
1t
CK
CK
CK
When a burst Read command is issued to a DDR SDRAM, a Precharge command may be issued to the same
bank before the Read burst is complete. The following functionality determines when a Precharge command
may be given during a Read burst and when a new Bank Activate command may be issued to the same bank.
1. For the earliest possible Precharge command without interrupting a Read burst, the Precharge command
may be given on the rising clock edge which is CL clock cycles before the end of the Read burst where CL
is the CAS Latency. A new Bank Activate command may be issued to the same bank after tRP (RAS
Precharge time).
2. When a Precharge command interrupts a Read burst operation, the Precharge command may be given on
the rising clock edge which is CL clock cycles before the last data from the interrupted Read burst where
CL is the CAS Latency. Once the last data word has been output, the output buffers are tristated. A new
Bank Activate command may be issued to the same bank after tRP.
3. For a Read with autoprecharge command, a new Bank Activate command may be issued to the same
bank after tRP where tRP begins on the rising clock edge which is CL clock cycles before the end of the
Read burst where CL is the CAS Latency. During Read with autoprecharge, the initiation of the internal
precharge occurs at the same time as the earliest possible external Precharge command would initiate a
precharge operation without interrupting the Read burst as described in 1 above.
4. For all cases above, tRP is an analog delay that needs to be converted into clock cycles. The number of
clock cycles between a Precharge command and a new Bank Activate command to the same bank equals
tRP/tCK (where tCK is the clock cycle time) with the result rounded up to the nearest integer number of
clock cycles. (Note that rounding to X.5 is not possible since the Precharge and Bank Activate commands
can only be given on a
rising
clock edge).
In all cases, a Precharge operation cannot be initiated unless tRAS(min) [minimum Bank Activate to Precharge
time] has been satisfied. This includes Read with autoprecharge commands where tRAS(min) must still be
satisfied such that a Read with autoprecharge command has the same timing as a Read command followed by
the earliest possible Precharge command which does not interrupt the burst.
Figure 13. Read interrupted by a precharge timing
相关PDF资料 |
PDF描述 |
|---|---|
| 25AV5-GA | FOR TV HORIZONTAL-DEFLECTION AMPLIFIER APPLICATIONS |
| 25CV100BE | Surface Mount Type Miniature, Super low profile 3.9mm height |
| 25CV10BE | Surface Mount Type Miniature, Super low profile 3.9mm height |
| 25CV68BE | Surface Mount Type Miniature, Super low profile 3.9mm height |
| 25CV22BE | Surface Mount Type Miniature, Super low profile 3.9mm height |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 256MB-FD | 制造商:PNY Technologies 功能描述:256MB USB, FOR IBM - Bulk |
| 256MB-FLASH | 制造商:STMicroelectronics 功能描述: |
| 256ME-250K | 制造商:ILLINOISCAPACITOR 制造商全称:Illinois Capacitor, Inc. 功能描述:Metallized Polyester Motor Run/AC Film Capacitors In Boxes |
| 256ME-350K | 制造商:ILLINOISCAPACITOR 制造商全称:Illinois Capacitor, Inc. 功能描述:Metallized Polyester Motor Run/AC Film Capacitors In Boxes |
| 256ME-400K | 制造商:ILLINOISCAPACITOR 制造商全称:Illinois Capacitor, Inc. 功能描述:Metallized Polyester Motor Run/AC Film Capacitors In Boxes |
发布紧急采购，3分钟左右您将得到回复。