128Mb: x4, x8, x16
SDRAM
Fixed-length or full-page WRITE bursts can be trun-
cated with the BURST TERMINATE command. When
truncating a WRITE burst, the input data applied coinci-
dent with the BURST TERMINATE command will be
ignored. The last data written (provided that DQM is
LOW at that time) will be the input data applied one clock
previous to the BURST TERMINATE command. This is
shown in Figure 19, where data n is the last desired data
element of a longer burst.
PRECHARGE
The PRECHARGE command (see Figure 20) is used to
deactivate the open row in a particular bank or the open
row in all banks. The bank(s) will be available for a subse-
quent row access some specified time (tRP) after the
PRECHARGE command is issued. Input A10 determines
whether one or all banks are to be precharged, and in the
case where only one bank is to be precharged, inputs
BA0, BA1 select the bank. When all banks are to be
precharged, inputs BA0, BA1 are treated as “Don’t Care.”
Once a bank has been precharged, it is in the idle state
and must be activated prior to any READ or WRITE com-
mands being issued to that bank.
T0
T1
T2
CLK
POWER-DOWN
Power-down occurs if CKE is registered LOW coinci-
dent with a NOP or COMMAND INHIBIT when no ac-
cesses are in progress. If power-down occurs when all
banks are idle, this mode is referred to as precharge
power-down; if power-down occurs when there is a row
active in any bank, this mode is referred to as active
power-down. Entering power-down deactivates the in-
put and output buffers, excluding CKE, for maximum
power savings while in standby. The device may not
remain in the power-down state longer than the refresh
period (64ms) since no refresh operations are performed
in this mode.
BURST
TERMINATE
NEXT
COMMAND
WRITE
COMMAND
ADDRESS
DQ
BANK,
COL n
(ADDRESS)
(DATA)
DIN
n
The power-down state is exited by registering a NOP
or COMMAND INHIBIT and CKE HIGH at the desired
clock edge (meeting tCKS). See Figure 21.
Figure 19
Terminating a WRITE Burst
CLK
( (
) )
CLK
( (
) )
CKE
CS#
HIGH
> t
CKS
t
CKS
CKE
( (
) )
( (
) )
( (
) )
COMMAND
NOP
NOP
ACTIVE
RAS#
t
All banks idle
RCD
Input buffers gated off
t
RAS
t
RC
CAS#
WE#
Enter power-down mode.
Exit power-down mode.
DON’T CARE
Figure 21
Power-Down
A0-A9
A10
All Banks
Bank Selected
BANK
ADDRESS
BA0,1
Figure 20
PRECHARGE Command
128Mb: x4, x8, x16 SDRAM
128MSDRAM_E.p65 – Rev. E; Pub. 1/02
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2001, Micron Technology, Inc.
24
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