SDRAM
AS4SD4M16
Austin Semiconductor, Inc.
with AUTO PRECHARGE. The disadvantage of the
PRECHARGE command is that it requires that the command
and address buses be available at the appropriate time to issue
the command; the advantage of the PRECHARGE command is
that it can be used to truncate fixed-length or full-page bursts.
Full-page READ bursts can be truncated with the
may be truncated with a BURST TERMINATE command,
provided that AUTO PRECHARGE was not activated. The
BURST TERMINATE command should be issued x cycles
before the clock edge at which the last desired data element is
valid, where x equals the CAS latency minus one. This is shown
in Figure 12 for each possible CAS latency; data element n + 3
is the last desired data element of a longer burst.
BURST TERMINATE command, and fixed-length READ bursts
T6
T0
T1
T2
T3
T4
T5
CLK
BURST
TERMINATE
NOP
READ
NOP
NOP
NOP
NOP
COMMAND
X = 1 cycles
BANK,
COL n
ADDRESS
DQ
DOUT
n+1
DOUT
n+3
DOUT
n
DOUT
n+2
CAS Latency = 2
T6
T7
T0
T1
T2
T3
T4
T5
CLK
COMMAND
ADDRESS
DQ
BURST
NOP
READ
NOP
NOP
NOP
NOP
NOP
TERMINATE
X = 2 cycles
BANK,
COL n
DOUT
n+2
DOUT
n
DOUT
n+1
DOUT
n+3
CAS Latency = 3
DON’T CARE
NOTE: DQM is LOW.
Figure 12
TERMINATING A READ BURST
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
AS4SD4M16
Rev. 2.1 6/05
18
AUSTIN [ AUSTIN SEMICONDUCTOR ]
