W631GG6KB-15 Datasheet, PDF (17/158 Pages) Winbond – Double Data Rate architecture: two data transfers per clock cycle

W631GG6KB
7.3.1.1 Burst Length, Type and Order
Accesses within a given burst may be programmed to sequential or interleaved order. The burst type
is selected via bit A3 as shown in Figure 5. The ordering of accesses within a burst is determined by
the burst length, burst type, and the starting column address as shown in Table 1. The burst length is
defined by bits A0-A1. Burst length options include fixed BC4, fixed BL8 and ‗on the fly‘ which allows
BC4 or BL8 to be selected coincident with the registration of a Read or Write command via A12/BC#.
Table 1 – Burst Type and Burst Order
Burst
Length
4
Chop
READ/
WRITE
READ
Starting Column Address
(A2, A1, A0)
000
001
Burst type = Sequential
(decimal)
A3 = 0
0,1,2,3,T,T,T,T
1,2,3,0,T,T,T,T
Burst type = Interleaved
(decimal)
A3 = 1
0,1,2,3,T,T,T,T
1,0,3,2,T,T,T,T
NOTES
1, 2, 3
1, 2, 3
010
2,3,0,1,T,T,T,T
2,3,0,1,T,T,T,T
1, 2, 3
011
3,0,1,2,T,T,T,T
3,2,1,0,T,T,T,T
1, 2, 3
100
4,5,6,7,T,T,T,T
4,5,6,7,T,T,T,T
1, 2, 3
101
5,6,7,4,T,T,T,T
5,4,7,6,T,T,T,T
1, 2, 3
110
6,7,4,5,T,T,T,T
6,7,4,5,T,T,T,T
1, 2, 3
111
7,4,5,6,T,T,T,T
7,6,5,4,T,T,T,T
1, 2, 3
WRITE
0,V,V
0,1,2,3,X,X,X,X
0,1,2,3,X,X,X,X
1, 2, 4, 5
1,V,V
4,5,6,7,X,X,X,X
4,5,6,7,X,X,X,X
1, 2, 4, 5
8
READ
000
0,1,2,3,4,5,6,7
0,1,2,3,4,5,6,7
2
001
1,2,3,0,5,6,7,4
1,0,3,2,5,4,7,6
2
010
2,3,0,1,6,7,4,5
2,3,0,1,6,7,4,5
2
011
3,0,1,2,7,4,5,6
3,2,1,0,7,6,5,4
2
100
4,5,6,7,0,1,2,3
4,5,6,7,0,1,2,3
2
101
5,6,7,4,1,2,3,0
5,4,7,6,1,0,3,2
2
110
6,7,4,5,2,3,0,1
6,7,4,5,2,3,0,1
2
111
7,4,5,6,3,0,1,2
7,6,5,4,3,2,1,0
2
WRITE
V,V,V
0,1,2,3,4,5,6,7
0,1,2,3,4,5,6,7
2, 4
Notes:
1. In case of burst length being fixed to 4 by MR0 setting, the internal write operation starts two clock cycles earlier than for the
BL8 mode. This means that the starting point for tWR and tWTR will be pulled in by two clocks. In case of burst length being
selected on-the-fly via A12/BC#, the internal write operation starts at the same point in time like a burst of 8 write operation.
This means that during on-the-fly control, the starting point for tWR and tWTR will not be pulled in by two clocks.
2. 0...7 bit number is value of CA[2:0] that causes this bit to be the first read during a burst.
3. T: Output driver for data and strobes are in high impedance.
4. V: a valid logic level (0 or 1), but respective buffer input ignores level on input pins.
5. X: Don't Care.
7.3.1.2 CAS Latency
The CAS Latency is defined by MR0 (bits A2, A4, A5 and A6) as shown in Figure 5. CAS Latency is
the delay, in clock cycles, between the internal Read command and the availability of the first bit of
output data. DDR3 SDRAM does not support any half-clock latencies. The overall Read Latency (RL)
is defined as Additive Latency (AL) + CAS Latency (CL); RL = AL + CL. For more information on the
supported CL and AL settings based on the operating clock frequency, refer to section 9.15 “Speed
Bins” on page 133. For detailed Read operation refer to section 7.13 “READ Operation” on page 42.
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Publication Release Date: Feb. 27, 2013
Revision A04