K4H281638B-TCB0000 Samsung Semiconductor, K4H281638B-TCB0000 Datasheet - Page 24

• Manufacturer Part Number: K4H281638B-TCB0000
• Manufacturer: Samsung Semiconductor

Specifications of K4H281638B-TCB0000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

128Mb DDR SDRAM
The following functionality establishes how a Write command may interrupt a Read burst.
1. For Write commands interrupting a Read burst, a Burst Terminate command is required to stop the read
2. It is illegal for a Write command to interrupt a Read with autoprecharge command.
3.3.3 Read Interrupted by a Read
the previous burst is interrupted, the remaining addresses are overridden by the new address with the full burst
length. The data from the first Read command continues to appear on the outputs until the CAS latency from
the interrupting Read command is satisfied.
appears. Read to Read interval is minimum 1 Clock.
3.3.4 Read Interrupted by a Write & Burst Stop
tion on the I/O bus by placing the DQ’s(Output drivers) in a high impedance state. To insure the DQ’s are tri-
stated one cycle before the beginning the write operation, Burst stop command must be applied at least 2
clock cycles for CL=2 and at least 3 clock cycles for CL=2.5 before the Write command.
CAS Latency=2
CAS Latency=2
A Burst Read can be interrupted before completion of the burst by new Read command of any bank. When
To interrupt a burst read with a write command, Burst Stop command must be asserted to avoid data conten-
burst and tristate the DQ bus prior to valid input write data. Once the Burst Terminate command has been
issued, the minimum delay to a Write command = RU(CL) [CL is the CAS Latency and RU means round up
to the nearest integer].
< Burst Length=4, CAS Latency=2 >
< Burst Length=4, CAS Latency=2 >
Command
Command
DQS
DQ s
DQS
DQ s
CK
CK
CK
CK
Figure 12. Read interrupted by a write and burst stop timing.
READ A
READ
0
0
Figure 11. Read interrupted by a read timing
Burst Stop
READ B
1
1
NOP
NOP
D
Dout 0 Dout 1
out
2
2
A
At this point the data from the interrupting Read command
0
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D
out
WRITE
NOP
A
1
D
3
3
out
B
0
D
out
NOP
Din 0
NOP
B
1
D
4
4
out
Din 1
B
2
D
out
NOP
Din 2
B
NOP
3
5
5
REV. 1.31 Nov. 3. 2001
Din 3
NOP
NOP
6
6
NOP
NOP
7
7
NOP
NOP
8
8