D A T A S H E E T
COMMAND DEFINITIONS
Writing specific address and data commands or
sequences into the command register initiates device
operations. Table 5 defines the valid register command
sequences. Writing incorrect address and data
values or writing them in the improper sequence
resets the device to reading array data.
however, the device ignores reset commands until the
operation is complete.
The reset command may be written between the
sequence cycles in an autoselect command sequence.
Once in the autoselect mode, the reset command must
be written to return to reading array data (also applies
to autoselect during Erase Suspend).
All addresses are latched on the falling edge of WE# or
CE#, whichever happens later. All data is latched on
the rising edge of WE# or CE#, whichever happens
first. Refer to the appropriate timing diagrams in the
“AC Characteristics” section.
If DQ5 goes high during a program or erase operation,
writing the reset command returns the device to
reading array data (also applies during Erase
Suspend).
Reading Array Data
Autoselect Command Sequence
The device is automatically set to reading array data
after device power-up. No commands are required to
retrieve data. The device is also ready to read array
data after completing an Embedded Program or
Embedded Erase algorithm.
The autoselect command sequence allows the host
system to access the manufacturer and devices codes,
and determine whether or not a sector is protected.
Table 5 shows the address and data requirements. This
method is an alternative to that shown in Table 4, which
After the device accepts an Erase Suspend command,
the device enters the Erase Suspend mode. The
system can read array data using the standard read
timings, except that if it reads at an address within
erase-suspended sectors, the device outputs status
data. After completing a programming operation in the
Erase Suspend mode, the system may once again
read array data with the same exception. See “Erase
Suspend/Erase Resume Commands” for more infor-
mation on this mode.
is intended for PROM programmers and requires V
on address bit A9.
ID
The autoselect command sequence is initiated by
writing two unlock cycles, followed by the autoselect
command. The device then enters the autoselect
mode, and the system may read at any address any
number of times, without initiating another command
sequence.
A read cycle at address XX00h or retrieves the manu-
facturer code. A read cycle at address XX01h in word
mode (or 02h in byte mode) returns the device code. A
read cycle containing a sector address (SA) and the
address 02h in word mode (or 04h in byte mode)
returns 01h if that sector is protected, or 00h if it is
unprotected. Refer to Tables 2 and 3 for valid sector
addresses.
The system must issue the reset command to re-
enable the device for reading array data if DQ5 goes
high, or while in the autoselect mode. See the “Reset
Command” section, next.
See also “Requirements for Reading Array Data” in the
“Device Bus Operations” section for more information.
The Read Operations table provides the read parame-
ters, and Figure 9 shows the timing diagram.
The system must write the reset command to exit the
autoselect mode and return to reading array data.
Reset Command
Writing the reset command to the device resets the
device to reading array data. Address bits are don’t
care for this command.
Word/Byte Program Command Sequence
The system may program the device by word or byte,
depending on the state of the BYTE# pin. Program-
ming is a four-bus-cycle operation. The program
command sequence is initiated by writing two unlock
write cycles, followed by the program set-up command.
The program address and data are written next, which
in turn initiate the Embedded Program algorithm. The
system is not required to provide further controls or tim-
ings. The device automatically provides internally
generated program pulses and verify the programmed
cell margin. Table 5 shows the address and data
requirements for the byte program command
sequence.
The reset command may be written between the
sequence cycles in an erase command sequence
before erasing begins. This resets the device to reading
array data. Once erasure begins, however, the device
ignores reset commands until the operation is
complete.
The reset command may be written between the
sequence cycles in a program command sequence
before programming begins. This resets the device to
reading array data (also applies to programming in
Erase Suspend mode). Once programming begins,
When the Embedded Program algorithm is complete,
the device then returns to reading array data and
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