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W3H32M64EA-400SBM 参数 Datasheet PDF下载

W3H32M64EA-400SBM图片预览
型号: W3H32M64EA-400SBM
PDF下载: 下载PDF文件 查看货源
内容描述: [DDR DRAM, 32MX64, CMOS, PBGA208, 16 X 20 MM, 1 MM PITCH, PLASTIC, BGA-208]
分类和应用: 动态存储器双倍数据速率内存集成电路
文件页数/大小: 27 页 / 1197 K
品牌: MERCURY [ MERCURY UNITED ELECTRONICS INC ]
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W3H32M64EA-XSBX  
ADVANCED  
FIGURE 5 – MODE REGISTER (MR) DEFINITION  
MODE REGISTER (MR)  
The mode register is used to dene the specic mode of operation  
of the DDR2 SDRAM. This denition includes the selection of a  
burst length, burst type, CL, operating mode, DLL RESET, write  
recovery, and power-down mode, as shown in Figure 5. Contents of  
the mode register can be altered by re-executing the LOAD MODE  
(LM) command. If the user chooses to modify only a subset of the  
MR variables, all variables (M0–M14) must be programmed when  
the command is issued.  
1
2
BA2 BA1 BA0 An A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0  
Address Bus  
16 15 14  
n
12 11 10  
PD WR  
9
8
7
6
5
4
3
2
1
0
Mode Register (Mx)  
0
MR  
0
DLL TM CAS# Latency BT Burst Length  
M2 M1 M0 Burst Length  
M12 PD Mode  
Mode  
Normal  
Test  
M7  
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Reserved  
Reserved  
4
0
Fast exit  
(normal)  
1
The mode register is programmed via the LM command (bits  
BA1–BA0 = 0, 0) and other bits (M12–M0) will retain the stored  
information until it is programmed again or the device loses power  
(except for bit M8, which is self-clearing). Reprogramming the  
mode register will not alter the contents of the memory array,  
provided it is performed correctly.  
1
Slow exit  
(low power)  
8
DLL Reset  
No  
M8  
0
Reserved  
Reserved  
Reserved  
Reserved  
1
Yes  
Write Recovery  
M11 M10 M9  
Reserved  
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
2
3
4
5
6
7
8
Burst Type  
Sequential  
Interleaved  
M3  
0
The LM command can only be issued (or reissued) when all  
banks are in the precharged state (idle state) and no bursts are in  
progress. The controller must wait the specied time tMRD before  
initiating any subsequent operations such as anACTIVE command.  
Violating either of these requirements will result in unspecied  
operation.  
1
CAS Latency (CL)  
M6 M5 M4  
Reserved  
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Reserved  
Reserved  
M15 M14  
Mode Register Definition  
3
4
5
6
7
0
0
1
1
0
1
0
1
Mode register (MR)  
Extended mode register (EMR)  
Extended mode register (EMR2)  
Extended mode register (EMR3)  
BURST LENGTH  
Burst length is dened by bits M0–M3, as shown in Figure 5. Read  
and write accesses to the DDR2 SDRAM are burst-oriented, with  
the burst length being programmable to either four or eight. The  
burst length dete rmines the maximum number of column locations  
that can be accessed for a given READ or WRITE command.  
Notes:  
1. M16 (BA2) is only applicable for densities 1Gb, reserved for future use, and  
must be programmed to “0.”  
When a READ or WRITE command is issued, a block of columns  
equal to the burst length is effectively selected. All accesses for  
that burst take place within this block, meaning that the burst  
will wrap within the block if a boundary is reached. The block is  
uniquely selected by A2–Ai when BL = 4 and by A3–Ai when BL =  
8 (where Ai is the most signicant column address bit for a given  
conguration). The remaining (least signicant) address bit(s)  
is (are) used to select the starting location within the block. The  
programmed burst length applies to both READ and WRITE bursts.  
2. Mode bits (Mn) with corresponding address balls (An) greater than M12 (A12)  
are reserved for future use and must be programmed to “0.”  
3. Not all listed WR and CL options are supported in any individual speed grade.  
BURST TYPE  
Accesses within a given burst may be programmed to be either  
sequential or interleaved. The burst type is selected via bit M3,  
as shown in Figure 5. The ordering of accesses within a burst is  
determined by the burst length, the burst type, and the starting  
column address, as shown in Table 2. DDR2 SDRAM supports  
4-bit burst mode and 8-bit burst mode only. For 8-bit burst mode,  
full interleave address ordering is supported; however, sequential  
address ordering is nibble-based.  
Microsemi Corporation reserves the right to change products or specications without notice.  
August 2011 © 2011 Microsemi Corporation. All rights reserved.  
Rev.1  
8
Microsemi Corporation • (602) 437-1520 • www.microsemi.com