differentiates the offerings in one place—
MT4LC16M4A7. The fifth field distinguishes
various options: A7 designates an 8K refresh and
T8 designates a 4K refresh for FPM DRAMs.
The 16 Meg x 4 DRAMs are high-speed CMOS,
dynamic random-access memory devices contain-ing
67,108,864 bits organized in a x4 configuration. The
MT4LC16M4A7 and MT4LC16M4T8 are functionally
organized as 16,777,216 locations containing four bits
each. The 16,777,216 memory locations are arranged in
8,192 rows by 2,048 columns for the MT4LC16M4A7 or
4,096 rows by 4,096 columns for the MT4LC16M4T8.
During READ or WRITE cycles, each location is uniquely
addressed via the address bits. First, the row address is
latched by the RAS# signal, then the column address by
CAS#. Both devices provide FAST-PAGE-MODE operation, allowing for fast successive data operations (READ,
WRITE, or READ-MODIFY-WRITE) within a given row.
The MT4LC16M4A7 and MT4LC16M4T8 must be
refreshed periodically in order to retain stored data.
FAST PAGE MODE ACCESS
Each location in the DRAM is uniquely addressable
as mentioned in the General Description. The data for
each location is accessed via the four I/O pins (DQ0DQ3). The WE# signal must be activated to execute a
WRITE operation; otherwise, a READ operation will be
performed. The OE# signal must be activated to enable
the DQ output drivers for a read access and can be
deactivated to disable output data if necessary.
FAST-PAGE-MODE operations are always initiated
with a row address strobed in by the RAS# signal,
followed by a column address strobed in by CAS#, just
like for single location accesses. However, subsequent
column locations within the row may then be accessed
at the page mode cycle time. This is accomplished by
cycling CAS# while holding RAS# LOW and entering
new column addresses with each CAS# cycle. Returning
RAS# HIGH terminates the FAST-PAGE-MODE operation.
DRAM REFRESH
The supply voltage must be maintained at the specified levels, and the refresh requirements must be met in
order to retain stored data in the DRAM. The refresh
requirements are met by refreshing all 8,192 rows (A7)
or all 4,096 rows (T8) in the DRAM array at least once
every 64ms. The recommended procedure is to execute
4,096 CBR REFRESH cycles, either uniformly spaced or
grouped in bursts, every 64ms. The MT4LC16M4A7
internally refreshes two rows for every CBR cycle,
16 MEG x 4
FPM DRAM
whereas the MT4LC16M4T8 refreshes one row for every
CBR cycle. So with either device, executing 4,096 CBR
cycles covers all rows. The CBR refresh will invoke the
internal refresh counter for automatic RAS# addressing. Alternatively, RAS#-ONLY REFRESH capability is
inherently provided. However, with this method only
one row is refreshed at a time; so for the MT4LC16M4A7,
8,192 RAS#-ONLY REFRESH cycles must be executed
every 64ms to cover all rows. Some compatibility issues
may become apparent. JEDEC strongly recommends
the use of CBR REFRESH for this device.
An optional self refresh mode is also available on the
“S” version. The self refresh feature is initiated by
performing a CBR REFRESH cycle and holding RAS#
LOW for the specified tRASS. The “S” option allows for
an extended refresh period of 128ms, or 31.25µs per
row for a 4K refresh and 15.625µs per row for an 8K
refresh, when using a distributed CBR REFRESH. This
refresh rate can be applied during normal operation, as
well as during a standby or battery backup mode.
The self refresh mode is terminated by driving RAS#
HIGH for a minimum time of tRPS. This delay allows for
the completion of any internal refresh cycles that may
be in process at the time of the RAS# LOW-to-HIGH
transition. If the DRAM controller uses a distributed
CBR refresh sequence, a burst refresh is not required
upon exiting self refresh. However, if the DRAM controller utilizes RAS#-ONLY or burst CBR refresh sequence, all rows must be refreshed within the average
internal refresh rate prior to the resumption of normal
operation.
STANDBY
Returning RAS# and CAS# HIGH terminates a
memory cycle and decreases chip current to a reduced
standby level. The chip is preconditioned for the next
cycle during the RAS# HIGH time.
Voltage on VCC Relative to VSS ................ -1V to +4.6V
Voltage on NC, Inputs or I/O Pins
Relative to VSS ..................................... -1V to +4.6V
Operating Temperature, TA (ambient) ... 0°C to +70°C
Storage Temperature (plastic) ............ -55°C to +150°C
Power Dissipation ................................................... 1W
*Stresses greater than those listed under “Absolute
Maximum Ratings” may cause permanent damage to
the device. This is a stress rating only, and functional
operation of the device at these or any other conditions
above those indicated in the operational sections of
this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may
affect reliability.
DC ELECTRICAL CHARACTERISTICS AND OPERATING CONDITIONS
(Notes: 1, 5, 6) (VCC = +3.3V ±0.3V)
PARAMETER/CONDITIONSYMBOLMINMAXUNITS NOTES
SUPPLY VOLTAGEVCC33.6V
INPUT HIGH VOLTAGE:
Valid Logic 1; All inputs, I/Os and any NCVIH2VCC + 0.3V26
INPUT LOW VOLTAGE:
Valid Logic 0; All inputs, I/Os and any NCVIL-0.30.8V 26
INPUT LEAKAGE CURRENT:
Any input at VIN (0V ≤ VIN≤ VCC + 0.3V);II-22µA
All other pins not under test = 0V
OUTPUT HIGH VOLTAGE:
IOUT = -2mAVOH2.4–V
OUTPUT LOW VOLTAGE:
IOUT = 2mAVOL–0.4V
OUTPUT LEAKAGE CURRENT:
Any output at VOUT (0V ≤ VOUT ≤ VCC + 0.3V);IOZ-55µ A
DQ is disabled and in High-Z state
STANDBY CURRENT: CMOS
(RAS# = CAS# VCC - 0.2V, DQs may be left open,ICC2ALL500500µA
other inputs: VIN VCC - 0.2V or VIN≤ 0.2V)
OPERATING CURRENT: Random READ/WRITEICC3-5170130mA25
Average power supply current-6160120
(RAS#, CAS#, address cycling: tRC = tRC [MIN])
OPERATING CURRENT: FAST PAGE MODEICC4-5100100mA25
Average power supply current (RAS# = VIL,-69090
CAS#, address cycling: tPC = tPC [MIN])
REFRESH CURRENT: RAS#-ONLYICC5-5170130mA22
Average power supply current-6160120
(RAS# cycling, CAS# = VIH: tRC = tRC [MIN])
REFRESH CURRENT: CBRICC6-5170130mA4, 7
Average power supply current-6160120
(RAS#, CAS#, address cycling: tRC = tRC [MIN])
REFRESH CURRENT: Extended (“S” version only)
Average power supply current: CAS# = 0.2V or
CBR cycling; RAS# = tRAS (MIN); WE# = VCC - 0.2V;ICC7ALL400400µA4, 7
A0-A11, OE# and DIN = VCC - 0.2V or 0.2V
(DIN may be left open)
REFRESH CURRENT: Self (“S” version only)
Average power supply current: CBR withICC8ALL400400µA4, 7
RAS# tRASS (MIN) and CAS# held LOW;
WE# = VCC - 0.2V; A0-A11, OE# and DIN =
VCC - 0.2V or 0.2V (DIN may be left open)
AC CHARACTERISTICS-5-6
PARAMETERSYMBOLMINMAXMINMAXUNITSNOTES
Access time from column address
Column-address hold time (referenced to RAS#)
Column-address setup time
Row-address setup time
Column address to WE# delay time
Access time from CAS#
Column-address hold time
CAS# pulse width
CAS# LOW to “Don’t Care” during Self Refresh
CAS# hold time (CBR Refresh)
CAS# to output in Low-Z
CAS# precharge time (FAST PAGE MODE)
Access time from CAS# precharge
CAS# to RAS# precharge time
CAS# hold time
CAS# setup time (CBR Refresh)
CAS# to WE# delay time
WRITE command to CAS# lead time
Data-in hold time
Data-in setup time
Output disable
Output enable time
OE# hold time from WE# during