MX29L1611
READ/RESET COMMAND
The read or reset operation is initiated by writing the
read/reset command sequence into the command
register. Microprocessor read cycles retrieve array data
from the memory. The device remains enabled for reads
until the CIR contents are altered by a valid command
sequence.
The device will automatically power-up in the read/reset
state. In this case, a command sequence is not required
for "read operation". Standard microprocessor read
cycles will retrieve array data. This default value ensures
that no spurious alteration of the memory content occurs
during the power transition. Refer to the AC Read
Characteristics and Waveforms for the specific timing
parameters.
The MX29L1611 is accessed like an EPROM. When CE
and OE are low and WE is high the data stored at the
memory location determined by the address pins is
asserted on the outputs. The outputs are put in the high
impedance state whenever CE or OE is high. This dual
line control gives designers flexibility in preventing bus
contention.
Note that the read/reset command is not valid when
program or erase is in progress.
After three-cycle command sequence is given, a
byte(word) load is performed by applying a low pulse on
the WE or CE input with CE or WE low (respectively) and
OE high. The address is latched on the falling edge of
CE or WE, whichever occurs last. The data is latched by
the first rising edge of CE or WE. Maximum of 128 bytes
of data may be loaded into each page by the same
procedure as outlined in the page program section
below.
BYTE-WIDE LOAD/WORD-WIDE LOAD
Byte(word) loads are used to enter the 128 bytes(64
words) of a page to be programmed or the software
codes for data protection. A byte load(word load) is
performed by applying a low pulse on the WE or CE input
with CE or WE low (respectively) and OE high. The
address is latched on the falling edge of CE or WE,
whichever occurs last. The data is latched by the first
rising edge of CE or WE.
Either byte-wide load or word-wide load is
determined(Byte = VIL or VIH is latched) on the falling
edge of the WE (or CE) during the 3rd command write
cycle.
PROGRAM
Any page to be programmed should have the page in the
erased state first, i.e. performing sector erase is
suggested before page programming can be performed.
The device is programmed on a page basis. If a
byte(word) of data within a page is to be changed, data
for the entire page can be loaded into the device. Any
byte(word) that is not loaded during the programming of
its page will be still in the erased state (i.e. FFH). Once
the bytes of a page are loaded into the device, they are
simultaneously programmed during the internal
programming period. After the first data byte(word) has
been loaded into the device, successive bytes(words)
are entered in the same manner. Each new byte(word)
to be programmed must have its high to low transition on
WE (or CE) within 30us of the low to high transition of WE
(or CE) of the preceding byte(word). A6 to A19 specify
the page address, i.e., the device is page-aligned on 128
bytes(64 words)boundary. The page address must be
valid during each high to low transition of WE or CE. A-
1 to A5 specify the byte address within the page, A0 to
A5 specify the word address withih the page. The
PAGE READ
The MX29L1611 offers "fast page mode read" function.
The users can take the access time advantage if keeping
CE, OE at low and the same page address (A3~A19
unchanged). Please refer to Figure 5-2 for detailed
timing waveform. The system performance could be
enhanced by initiating 1 normal read and 7 fast page
reads(for word mode A0~A2) or 15 fast page reads(for
byte mode altering A-1~A2).
PAGE PROGRAM
To initiate Page program mode, a three-cycle command
sequence is required. There are two "unlock" write
cycles. These are followed by writing the page program
command-A0H.
Any attempt to write to the device without the three-cycle
command sequence will not start the internal Write State
Machine(WSM), no data will be written to the device.
P/N:PM0511
REV. 2.4, NOV. 06, 2001
9
MCNIX [ MACRONIX INTERNATIONAL ]
