IBM0316809C IBM0316409C
IBM0316169C
16Mbit Synchronous DRAM
Burst Stop Command
Once a burst read or write operation has been initiated, there exist several methods in which to terminate the
burst operation prematurely. These methods include using another Read or Write Command to interrupt an
existing burst operation, use a Precharge Command to interrupt a burst cycle and close the active bank, or
using the Burst Stop Command to terminate the existing burst operation but leave the bank open for future
Read or Write Commands to the same page of the active bank. When interrupting a burst with another Read
or Write Command care must be taken to avoid DQ contention. The Burst Stop Command, however, has the
fewest restrictions making it the easiest method to use when terminating a burst operation before it has been
completed. The Burst Stop Command is defined by having RAS and CAS high with CS and WE low at the ris-
ing edge of the clock.
When using the Burst Stop Command during a burst read cycle, the data DQ’s go to a high impedance state
after a delay which is equal to the CAS Latency set in the Mode Register.
Termination of a Burst Read Operation (Burst Length > 4, CAS latency = 1, 2, 3)
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
Burst
Stop
READ A
NOP
NOP
NOP
NOP
NOP
NOP
NOP
COMMAND
The burst ends after a delay equal to the CAS latency.
CAS latency = 1
DOUT A
DOUT A
DOUT A
DOUT A
DOUT A
DOUT A
DOUT A
0
1
0
2
3
2
1
t
CK1, DQ’s
CAS latency = 2
DOUT A
DOUT A
DOUT A
3
1
0
t
CK2, DQ’s
CAS latency = 3
DOUT A
DOUT A
3
2
t
CK3, DQ’s
If a Burst Stop Command is issued during a burst write operation, then any residual data from the burst write
cycle will be ignored. Data that is presented on the DQ pins before the Burst Stop Command is registered will
be written to the memory.
Termination of a Burst Write Operation (Burst Length =X, CAS latency = 1,2,3)
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
Burst
Stop
NOP
WRITE A
NOP
NOP
NOP
NOP
NOP
NOP
COMMAND
CAS latency = 1,2,3
don’t care
DIN A
0
DIN A
DIN A
2
1
DQ’s
Input data for the Write is masked.
©IBM Corporation, 1996. All rights reserved.
Use is further subject to the provisions at the end of this document.
07H3997
SA14-4711-02
Revised 05/96
Page 18 of 100
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