CMS4A16LAx–75Ex
Table 2. Burst Length Definition.
Order of Accesses within a Burst
Burst Length
Starting Column Address
Type=Sequential
A0
2
0
1
A1 A0
00
4
01
10
11
A2 A1 A0
000
001
010
8
011
100
101
110
111
Full Page(y)
n=A0-A8(location 0-y)
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
Bn, Bn+1, Bn+2…..Bn,…
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
Not supported
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
1-0
0-1
1-0
Type=Interleaved
Operating Mode
The normal operating mode is selected by setting M7 and M8
to zero; the other combinations of values for M7 and M8 are
reserved for future use and/or test modes.Test modes
and reserved states should not be used because unknown
operation or incompatibility with future versions may result.
CAS Latency
The CAS latency is the delay, in clock cycles, between the
registration of a READ command and the availability of the
first piece of output data. The latency can be set to one, two,
or three clocks. If a READ command is registered at clock edge
r,
and the latency is
q
clocks, the data will be available by clock
edge
r + q.
The DQs will start driving as a result of the clock
edge one cycle earlier
(r + q- 1),
and provided that the relevant
access times are met, the data will be valid by clock edge
r + q.
For example, assumi ng th at th e clock cycle time is
such that all relevant access times are met, if a READ
command is registered at T0 and the latency is programmed
to two clocks, the DQs will start driving after T1 and the data
will be valid by T2, as shown in Figure 2.
Table 3 indicates the operating frequencies at which each CAS
latency setting can be used. Reserved states should not be
used as unknown operation or incompatibility with future
versions may result.
Write Burst Mode
When M9=0, the burst length programmed via M0-M2 applies to
both READ and WRITE bursts; when M9=1, the programmed
burst length applies to READ bursts, but write accesses are
single-location (non-burst) accesses.
Rev. 0.5, May. ‘07
9
FIDELIX [ FIDELIX ]
