OBSOLETE
2, 4 MEG x 72
NONBUFFERED DRAM DIMMs
PART NUMBERS
EDO PAGE MODE
EDO Operating Mode
EDO PAGE MODE, designated by the “X” version, is an
accelerated FAST-PAGE-MODEcycle. The primary advan-
tage of EDO is the availability of data-out even after CAS#
goes back HIGH. EDO provides for CAS# precharge time
(tCP) to occur without the output data going invalid. This
elimination of CAS# output control provides for pipelined
READs.
PART NUMBER
CONFIGURATION
2 Meg x 72 ECC
2 Meg x 72 ECC
4 Meg x 72 ECC
4 Meg x 72 ECC
SPEED
50ns
60ns
50ns
60ns
MT9LD272AG-5 X
MT9LD272AG-6 X
MT18LD472AG-5 X
MT18LD472AG-6 X
FAST-PAGE-MODE modules have traditionally turned
the output buffers off (High-Z) with the rising edge of
CAS#. EDO-PAGE-MODE DRAMs operate like FAST-
PAGE-MODE DRAMs, except data will remain valid or
become valid after CAS# goes HIGH during READs, pro-
vided RAS# and OE# are held LOW. If OE# is pulsed while
RAS# and CAS# are LOW, data will toggle from valid data
to High-Z and back to the same valid data. If OE# is toggled
or pulsed after CAS# goes HIGH while RAS# remains
LOW, data will transition to and remain High-Z.
During an application, if the DQ outputs are wire OR’d,
OE#must be used to disable idle banks ofDRAMs. Alterna-
tively, pulsing WE# to the idle banks during CAS# HIGH
time will also High-Z the outputs. Independent of OE#
control, the outputs will disable after tOFF, which is refer-
enced from the rising edge of RAS# or CAS#, whichever
occurs last. (Refer to the 4 Meg x 4 [MT4LC4M4E8] DRAM
data sheet for additional information on EDO functional-
ity.)
FPM Operating Mode
PART NUMBER
CONFIGURATION
2 Meg x 72 ECC
4 Meg x 72 ECC
SPEED
60ns
MT9LD272AG-6
MT18LD472AG-6
60ns
GENERAL DESCRIPTION
The MT9LD272A(X) and MT18LD472A(X) are randomly
accessed 16MB and 32MB memories organized in a x72
configuration. They are specially processed to operate from
3V to 3.6V for low-voltage memory systems.
During READ or WRITE cycles, each bit is uniquely
addressed through the 21/ 22 address bits, which are en-
tered 11 bits (A0-A10) at RAS# time and 10/ 11 bits (A0-
A10) at CAS# time.
READ and WRITE cycles are selected with the WE#
input. A logic HIGH on WE# dictates read mode, while a
logic LOW on WE# dictates write mode. During a WRITE
cycle, data-in (D) is latched by the falling edge of WE# or
CAS#, whichever occurs last. An EARLY WRITE occurs
when WE# is taken LOW prior to CAS# falling. A LATE
WRITE or READ-MODIFY-WRITE occurs when WE# falls
after CAS# was taken LOW. During EARLY WRITE cycles,
the data-outputs (Q) will remain High-Z regardless of the
state of OE#. During LATE WRITE or READ-MODIFY-
WRITEcycles,OE#must be taken HIGH to disable the data-
outputs prior to applying input data. If a LATE WRITE or
READ-MODIFY-WRITE is attempted while keeping OE#
LOW, no WRITEwill occur, and the data-outputs will drive
read data from the accessed location.
REFRESH
Returning RAS# and CAS# HIGH terminates a memory
cycle and decreases chip current to a reduced standby level.
Also, the chip is preconditioned for the next cycle during
the RAS# HIGH time. Correct memory cell data is pre-
served by maintaining power and executing any RAS#
cycle (READ, WRITE) or RAS# REFRESH cycle (RAS#-
ONLY, CBR or HIDDEN) so that all combinations of RAS#
t
addresses (A0-A9/ A10) are executed at least every REF,
regardless of sequence. The CBR REFRESH cycle will in-
voke the internal refresh counter for automatic RAS# ad-
dressing.
SERIAL PRESENCE-DETECT OPERATION
This module family incorporates serial presence-detect
(SPD). The SPD function is implemented using a 2,048-bit
EEPROM. This nonvolatile storage device contains 256
bytes. The first 128 bytes can be programmed by Micron to
identify the module type and various DRAM organizations
and timing parameters. The remaining 128 bytes of storage
are available for use by the customer. System READ/
WRITE operations between the master (system logic) and
the slave EEPROM device (DIMM) occur via a standard IIC
bus using the DIMM’s SCL (clock) and SDA (data) signals,
FAST PAGE MODE
FAST-PAGE-MODE operations allow faster data opera-
tions (READ or WRITE) within a row-address-defined
page boundary. The FAST-PAGE-MODE cycle is always
initiated with a row address strobed in by RAS#, followed
by a column address strobed in by CAS#. Additional col-
umns may be accessed by providing valid column
addresses, strobing CAS# and holding RAS# LOW , thus
executing faster memory cycles. Returning RAS# HIGH
terminates the FAST-PAGE-MODE operation.
2, 4 Meg x 72 Nonbuffered DRAM DIMMs
DM60.p65 – Rev. 6/98
Micron Technology, Inc., reserves the right to change products or specifications without notice.
1998, Micron Technology, Inc.
2
MICRON [ MICRON TECHNOLOGY ]
