W3E32M64S-XBX Datasheet, PDF (7/17 Pages) White Electronic Designs Corporation – 32Mx64 DDR SDRAM

White Electronic Designs
W3E32M64S-XBX
FIGURE 3 – MODE REGISTER DEFINITION
BA1 BA0 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 Address Bus
0*
0*
Operating Mode
* M14 and M13
(BA0 and BA1 must be
"0, 0" to select
the base mode register
(vs. the extended
mode register).
CAS Latency BT Burst Length
Mode Register (Mx)
M2 M1 M0
0 00
0 01
0 10
0 11
1 00
1 01
1 10
1 11
Burst Length
M3 = 0
Reserved
2
4
8
Reserved
Reserved
Reserved
Reserved
M3 = 1
Reserved
2
4
8
Reserved
Reserved
Reserved
Reserved
M3
0
1
M6 M5 M4
0 00
0 01
0 10
0 11
1 00
1 01
1 10
1 11
Burst Type
Sequential
Interleaved
CAS Latency
Reserved
Reserved
2
Reserved
Reserved
Reserved
2.5
Reserved
M12 M11 M10 M9
M8
M7
M6-M0
Operating Mode
0
0
0
0
0
0
Valid
Normal Operation
0
0
0
0
1
0
Valid
Normal Operation/Reset DLL
-
-
-
-
-
-
-
All other states reserved
TABLE 1 – BURST DEFINITION
Burst
Length
2
4
8
Starting Column
Address
A0
0
1
A1 A0
00
01
10
11
A2 A1 A0
000
001
010
011
100
101
110
111
Order of Accesses Within a Burst
Type = Sequential Type = Interleaved
0-1
0-1
1-0
1-0
0-1-2-3
1-2-3-0
2-3-0-1
3-0-1-2
0-1-2-3
1-0-3-2
2-3-0-1
3-2-1-0
0-1-2-3-4-5-6-7
1-2-3-4-5-6-7-0
2-3-4-5-6-7-0-1
3-4-5-6-7-0-1-2
4-5-6-7-0-1-2-3
5-6-7-0-1-2-3-4
6-7-0-1-2-3-4-5
7-0-1-2-3-4-5-6
0-1-2-3-4-5-6-7
1-0-3-2-5-4-7-6
2-3-0-1-6-7-4-5
3-2-1-0-7-6-5-4
4-5-6-7-0-1-2-3
5-4-7-6-1-0-3-2
6-7-4-5-2-3-0-1
7-6-5-4-3-2-1-0
NOTES:
1. For a burst length of two, A1-Ai select two-data-element block; A0 selects the
starting column within the block.
2. For a burst length of four, A2-Ai select four-data-element block; A0-1 select the
starting column within the block.
3. For a burst length of eight, A3-Ai select eight-data-element block; A0-2 select the
starting column within the block.
4. Whenever a boundary of the block is reached within a given sequence above, the
following access wraps within the block.
WRITE
The WRITE command is used to initiate a burst write
access to an active row. The value on the BA0, BA1 inputs
selects the bank, and the address provided on inputs A0-9
selects the starting column location. The value on input A10
determines whether or not AUTO PRECHARGE is used. If
AUTO PRECHARGE is selected, the row being accessed
will be precharged at the end of the WRITE burst; if AUTO
PRECHARGE is not selected, the row will remain open for
subsequent accesses. Input data appearing on the D/Qs
is written to the memory array subject to the DQM input
logic level appearing coincident with the data. If a given
DQM signal is registered LOW, the corresponding data
will be written to memory; if the DQM signal is registered
HIGH, the corresponding data inputs will be ignored, and a
WRITE will not be executed to that byte/column location.
PRECHARGE
The PRECHARGE command is used to deactivate the
open row in a particular bank or the open row in all banks.
The bank(s) will be available for a subsequent row access
a specified time (tRP) after the PRECHARGE command is
issued. Except in the case of concurrent auto precharge,
where a READ or WRITE command to a different bank is
July 2006
Rev. 3
7
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