64Mb: x32
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 coin-
cident 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 (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 subsequent row access some specified time (tRP) af-
ter 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 and BA1 select the bank.
When all banks are to be precharged, inputs BA0 and
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 commands being issued to
that bank.
Figure 19
Terminating a WRITE Burst
T0
T1
T2
POWER-DOWN
CLK
Power-down occurs if CKE is registered LOW coinci-
dent with a NOP or COMMAND INHIBIT when no ac-
cesses 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 deacti-
vates the input 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
NOTE: DQMs are LOW.
The power-down state is exited by registering a NOP
or COMMAND INHIBIT and CKE HIGH at the desired
t
clock edge (meeting CKS).
Figure 20
PRECHARGECommand
Figure 21
CLK
Power-Down
CKE
CS#
HIGH
( (
) )
( (
CLK
) )
> t
CKS
t
CKS
CKE
( (
) )
( (
) )
( (
) )
RAS#
COMMAND
NOP
NOP
ACTIVE
t
All banks idle
RCD
CAS#
WE#
Input buffers gated off
t
RAS
t
RC
Enter power-down mode.
Exit power-down mode.
DON’T CARE
A0–A9
A10
All Banks
Bank Selected
BANK
ADDRESS
BA0, 1
64Mb: x32 SDRAM
64MSDRAMx32_5.p65 – Rev. B; Pub. 6/02
MicronTechnology,Inc.,reservestherighttochangeproductsorspecificationswithoutnotice.
©2002,MicronTechnology,Inc.
21
MICRON [ MICRON TECHNOLOGY ]
