Integrated Circuit Solution Inc.
The IC41C16100A(S) and IC41LV16100A(S) is a CMOS
DRAM optimized for high-speed bandwidth, low power
applications. During READ or WRITE cycles, each bit is
uniquely addressed through the 16 address bits. These
are entered ten bits (A0-A9) at a time. The row address is
latched by the Row Address Strobe (
RAS). The column
address is latched by the Column Address Strobe (
RAS is used to latch the first ten bits and CAS is used the
latter ten bits.
The IC41C16100A(S) and IC41LV16100A(S) has two
LCAS and UCAS. The LCAS and UCAS inputs
internally generates a
CAS signal functioning in an iden-
tical manner to the single
CAS input on the other 1M x 16
DRAMs. The key difference is that each
CAS controls its
corresponding I/O tristate logic (in conjunction with
WE and RAS). LCAS controls I/O0 through I/O7 and
UCAS controls I/O8 through I/O15.
The IC41C16100A(S) and IC41LV16100A(S)
tion is determined by the first
CAS (LCAS or UCAS)
transitioning LOW and the last transitioning back HIGH.
CAS controls give the IC41C16100A(S) and
IS41LV16100A(S) both BYTE READ and BYTE WRITE
A memory cycle is initiated by bring
RAS LOW and it is
terminated by returning both
RAS and CAS HIGH. To
ensures proper device operation and data integrity any
memory cycle, once initiated, must not be ended or
aborted before the minimum tRAS time has expired. A new
cycle must not be initiated until the minimum precharge
time tRP, tCP has elapsed.
A read cycle is initiated by the falling edge of
CAS or OE,
whichever occurs last, while holding
WE HIGH. The
column address must be held for a minimum time specified
by tAR. Data Out becomes valid only when tRAC, tAA, tCAC
and tOEA are all satisfied. As a result, the access time is
dependent on the timing relationships between these
A write cycle is initiated by the falling edge of
WE, whichever occurs last. The input data must be valid
at or before the falling edge of
CAS or WE, whichever
To retain data, 1,024 refresh cycles are required in each
16 ms period. There are two ways to refresh the memory.
1. By clocking each of the 1,024 row addresses (A0
through A9) with
RAS at least once every 16 ms. Any
read, write, read-modify-write or
RAS-only cycle re-
freshes the addressed row.
2. Using a
CAS-before-RAS refresh cycle. CAS-before-
RAS refresh is activated by the falling edge of RAS,
CAS LOW. In CAS-before-RAS refresh
cycle, an internal 10-bit counter provides the row ad-
dresses and the external address inputs are ignored.
CAS-before-RAS is a refresh-only mode and no data
access or device selection is allowed. Thus, the output
remains in the High-Z state during the cycle.
Self Refresh Cycle
The Self Refresh allows the user a dynamic refresh, data
retention mode at the extended refresh period of 128 ms.
i.e., 125 µs per row when using distributed CBR refreshes.
The feature also allows the user the choice of a fully static,
low power data retention mode. The optional Self Refresh
feature is initiated by performing a CBR Refresh cycle and
RAS LOW for the specified tRASS.
The Self Refresh mode is terminated by driving
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 refresh sequence,
a burst refresh is not required upon exiting Self Refresh.
However, if the DRAM controller utilizes a
burst refresh sequence, all 1,024 rows must be refreshed
within the average internal refresh rate, prior to the re-
sumption of normal operation.
Extended Data Out Page Mode
EDO page mode operation permits all 1,024 columns
within a selected row to be randomly accessed at a high
In EDO page mode read cycle, the data-out is held to the
CAS cycle’s falling edge, instead of the rising edge.
For this reason, the valid data output time in EDO page
mode is extended compared with the fast page mode. In
the fast page mode, the valid data output time becomes
shorter as the
CAS cycle time becomes shorter. Therefore,
in EDO page mode, the timing margin in read cycle is
larger than that of the fast page mode even if the
cycle time becomes shorter.
In EDO page mode, due to the extended data function, the
CAS cycle time can be shorter than in the fast page mode
if the timing margin is the same.
The EDO page mode allows both read and write opera-
tions during one
RAS cycle, but the performance is
equivalent to that of the fast page mode in that case.
After application of the VCC supply, an initial pause of
200 µs is required followed by a minimum of eight initial-
ization cycles (any combination of cycles containing a
During power-on, it is recommended that
RAS track with
VCC or be held at a valid VIH to avoid current surges.