mt48lc1m16a1 Micron Semiconductor Products, mt48lc1m16a1 Datasheet - Page 10

• Manufacturer Part Number: mt48lc1m16a1
• Description: Synchronous Dram
• Manufacturer: Micron Semiconductor Products

COMMAND INHIBIT
commands from being executed by the SDRAM, re-
gardless of whether the CLK signal is enabled. The
SDRAM is effectively deselected. Operations already in
progress are not affected.
NO OPERATION (NOP)
perform a NOP to an SDRAM which is selected (CS# is
LOW). This prevents unwanted commands from being
registered during idle or wait states. Operations already
in progress are not affected.
LOAD MODE REGISTER
BA. See Mode Register heading in Register Definition
section. The LOAD MODE REGISTER command can
only be issued when all banks are idle, and a subsequent
executable command cannot be issued until
met.
ACTIVE
a row in a particular bank for a subsequent access. The
value on the BA input selects the bank, and the address
provided on inputs A0-A10 selects the row. This row
remains active (or open) for accesses until a PRECHARGE
command is issued to that bank. A PRECHARGE com-
mand must be issued before opening a different row in
the same bank.
READ
access to an active row. The value on the BA input
selects the bank, and the address provided on inputs
A0-A7 selects the starting column location. The value
on input A10 determines whether or not AUTO
PRECHARGE is used. If AUTO PRECHARGE is selected,
the row being accessed will be precharged at the end of
the READ burst; if AUTO PRECHARGE is not selected,
the row will remain open for subsequent accesses. Read
data appears on the DQs, subject to the logic level on
the DQM inputs two clocks earlier. If a given DQM
signal was registered HIGH, the corresponding DQs
will be High-Z two clocks later; if the DQM signal was
registered LOW, the DQs will provide valid data.
WRITE
write access to an active row. The value on the BA input
selects the bank, and the address provided on inputs
16Mb: x16 IT SDRAM
16MSDRAMx16IT.p65 – Rev. 5/99
The COMMAND INHIBIT function prevents new
The NO OPERATION (NOP) command is used to
The Mode Register is loaded via inputs A0-A10 and
The ACTIVE command is used to open (or activate)
The READ command is used to initiate a burst read
The WRITE command is used to initiate a burst
t
MRD is
10
A0-A7 selects the starting column location. The value
on input A10 determines whether or not AUTO
PRECHARGE is used. If AUTO PRECHARGE is selected,
the row being accessed will be precharged at the end of
the WRITE burst; if AUTO PRECHARGE is not selected,
the row will remain open for subsequent accesses.
Input data appearing on the DQs is written to the
memory array subject to the DQM input logic level
appearing coincident with the data. If a given DQM
signal is registered LOW, the corresponding data will be
written to memory; if the DQM signal is registered
HIGH, the corresponding data inputs will be ignored,
and a WRITE will not be executed to that byte/column
location.
PRECHARGE
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 a specified time (
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. Otherwise 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 com-
mands being issued to that bank.
AUTO PRECHARGE
same individual-bank PRECHARGE function described
above, but without requiring an explicit command.
This is accomplished by using A10 to enable AUTO
PRECHARGE in conjunction with a specific READ or
WRITE command. A precharge of the bank/row that is
addressed with the READ or WRITE command is auto-
matically performed upon completion of the READ or
WRITE burst, except in the full-page burst mode, where
AUTO PRECHARGE does not apply. AUTO
PRECHARGE is nonpersistent in that it is either enabled
or disabled for each individual READ or WRITE com-
mand.
is initiated at the earliest valid stage within a burst. The
user must not issue another command to the same
bank until the precharge time (
is determined as if an explicit PRECHARGE command
was issued at the earliest possible time, as described for
each burst type in the Operation section of this data
sheet.
The PRECHARGE command is used to deactivate
AUTO PRECHARGE is a feature which performs the
AUTO PRECHARGE ensures that the PRECHARGE
Micron Technology, Inc., reserves the right to change products or specifications without notice.
t
RP) after the PRECHARGE
t
RP) is completed. This
16Mb: x16
IT SDRAM
©1999, Micron Technology, Inc.