
10
21445E5
November 1, 2006
D A T A  S H E E T
COMMAND DEFINITIONS
Writing specific address and data commands or se-
quences into the command register initiates device 
operations. The Command Definitions table defines the 
valid register command sequences. Writing 
incorrect
address and data values
 or writing them in the 
im-
proper sequence
 resets the device to reading array 
data. 
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.
Reading Array Data
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 Em-
bedded Erase algorithm.
After the device accepts an Erase Suspend command, 
the device enters the Erase Suspend mode. The sys-
tem 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.
The system 
must
 issue the reset command to re-en-
able the device for reading array data if DQ5 goes high, 
or while in the autoselect mode. See the 
“Reset Com-
mand”
 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 Read Operation Timings diagram shows the 
timing diagram.
Reset Command
Writing the reset command to the device resets the de-
vice to reading array data. Address bits are don’t care 
for this command. 
The reset command may be written between the se-
quence cycles in an erase command sequence before 
erasing begins. This resets the device to reading array 
data. Once erasure begins, however, the device ig-
nores reset commands until the operation is complete.
The reset command may be written between the se-
quence 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, 
however, the device ignores reset commands until the 
operation is complete.
The reset command may be written between the se-
quence 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).
If DQ5 goes high during a program or erase operation, 
writing the reset command returns the device to read-
ing array data (also applies during Erase Suspend).
Autoselect Command Sequence
The autoselect command sequence allows the host 
system to access the manufacturer and devices codes, 
and determine whether or not a sector is protected. 
The Command Definitions table shows the address 
and data requirements. This method is an alternative to 
that shown in the Autoselect Codes (High Voltage 
Method) table, which is intended for PROM program-
mers and requires V
ID
 on address bit A9.
The autoselect command sequence is initiated by writ-
ing 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 returns 
the device code. A read cycle containing a sector ad-
dress (SA) and the address 02h in returns 01h if that 
sector is protected, or 00h if it is unprotected. Refer to 
the Sector Address tables for valid sector addresses.
The system must write the reset command to exit the 
autoselect mode and return to reading array data.
Byte Program Command Sequence
Programming is a four-bus-cycle operation. The pro-
gram 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 al-
gorithm. The system is 
not
 required to provide further 
controls or timings. The device automatically provides 
internally generated program pulses and verify the pro-
grammed cell margin. The Command Definitions take 
shows the address and data requirements for the byte 
program command sequence.
When the Embedded Program algorithm is complete, 
the device then returns to reading array data and ad-
dresses are no longer latched. The system can 
determine the status of the program operation by using 
DQ7 or DQ6. See “Write Operation Status” for informa-
tion on these status bits.