ADVANCE
512Mb: x4, x8, x16
DDR SDRAM
the sequential and the interleaved burst types.
Reserved states should not be used, as unknown
operation or incompatibility with future versions may
result.
When a READ or WRITE command is issued, a block
of columns equal to the burst length is effectively se-
lected. 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 se-
lected by A1-Ai when the burst length is set to two, by
A2-Ai when the burst length is set to four and by A3-Ai
when the burst length is set to eight (where Ai is the
most significant column address bit for a given con-
figuration). The remaining (least significant) 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.
Burst Type
Accesses within a given burst may be programmed
to be either sequential or interleaved; this is referred to
as the burst type and is selected via bit M3.
The ordering of accesses within a burst is deter-
mined by the burst length, the burst type and the start-
ing column address, as shown in Table 1.
BA1 BA0 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
Address Bus
Table 1
Burst Definition
Burst
Length
Starting Column
Address
A0
0
1
A1 A0
0
0
0
1
1
0
1
1
A2 A1 A0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Order of Accesses Within a Burst
Type = Sequential
Type = Interleaved
0-1
1-0
0-1-2-3
1-2-3-0
2-3-0-1
3-0-1-2
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
1-0
0-1-2-3
1-0-3-2
2-3-0-1
3-2-1-0
0-1-2-3-4-5-6-7
1-0-3-2-5-4-7-6
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
14 13 12 11 10 9
8
Operating Mode
0* 0*
* M14 and M13 (BA0 and BA1)
must be “0, 0” to select the
base mode register (vs. the
extended mode register).
7
6 5 4 3 2 1 0
CAS Latency BT Burst Length
Mode Register (Mx)
Burst Length
M2 M1 M0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
M3 = 0
Reserved
2
4
8
Reserved
Reserved
Reserved
Reserved
M3 = 1
Reserved
2
4
8
Reserved
Reserved
Reserved
Reserved
2
4
M3
0
1
Burst Type
Sequential
Interleaved
8
M6 M5 M4
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
CAS Latency
Reserved
Reserved
2
Reserved
Reserved
Reserved
2.5
Reserved
M12 M11 M10 M9 M8 M7
0
0
-
0
0
-
0
0
-
0
0
-
0
1
-
0
0
-
M6-M0
Valid
Valid
-
Operating Mode
Normal Operation
Normal Operation/Reset DLL
All other states reserved
Figure 1
Mode Register Definition
NOTE:
1. For a burst length of two, A1-Ai select the two-
data-element block; A0 selects the first access
within the block.
2. For a burst length of four, A2-Ai select the four-
data-element block; A0-A1 select the first access
within the block.
3. For a burst length of eight, A3-Ai select the eight-
data-element block; A0-A2 select the first access
within the block.
4. Whenever a boundary of the block is reached
within a given sequence above, the following
access wraps within the block.
512Mb: x4, x8, x16 DDR SDRAM
512Mx4x8x16DDR_B.p65 – Rev. B; Pub 4/01
10
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2001, Micron Technology, Inc.
MICRON [ MICRON TECHNOLOGY ]
