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16Mb: x16 SDRAM
16MSDRAMx16.p65
–
Rev. 8/99
Micron Technology, Inc., reserves the right to change products or specifications without notice.
1999, Micron Technology, Inc.
21
16Mb: 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
coincident 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.
Figure 21
POWER-DOWN
Figure 20
PRECHARGE Command
Figure 19
Terminating a WRITE Burst
CS#
WE#
CAS#
RAS#
CKE
CLK
A10
BA
BANK 1
HIGH
BANK 0 and 1
BANK 0 or 1
BANK 0
A0-A9
tRAS
tRC
tRCD
All banks idle
Input buffers gated off
Exit POWER-
DOWN mode
(
)
(
)
(
)
(
)
(
)
(
)
tCKS
< tCKS
COMMAND
NOP
ACTIVE
Enter POWER-
DOWN mode
NOP
CLK
CKE
(
)
(
)
(
)
(
)
DON
’
T CARE
CLK
DQ
DIN
n
(Data)
T2
T1
T0
COMMAND
ADDRESS
BURST
TERMINATE
WRITE
Next
Command
BANK,
COL
n
NOTE:
DQMs are low
(Address)
PRECHA RGE
The PRECHARGE command is used to deactivate
the open row in a particular bank or the open row in
all banks (see Figure 20). The bank(s) will be available
for a subsequent row access some specified time (
t
RP)
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, input BA selects the bank. When all
banks are to be precharged, input BA is 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 commands being issued to that bank.
POWER-DOWN
POWER-DOWN occurs if CKE is registered LOW
coincident with a NOP or COMMAND INHIBIT, when
no accesses are in progress (see Figure 21). 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 either bank, this
mode is referred to as active power-down. Entering
power-down deactivates the input and output buff-
ers, 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.
The power-down state is exited by registering a NOP
or COMMAND INHIBIT and CKE HIGH at the desired
clock edge (meeting
t
CKS).