DQ6, or RY/BY#. See “Write Operation Status” for in-
formation on these status bits.
Any commands written to the device during the Em-
bedded Program Algorithm are ignored. Note that a
hardware reset immediately terminates the program-
ming operation. The program command sequence
should be reinitiated once the device has reset to read-
ing array data, to ensure data integrity.
Programming is allowed in any sequence and across
sector boundaries. A bit cannot be programmed
from a “0” back to a “1”. Attempting to do so may halt
the operation and set DQ5 to “1”, or cause the Data#
Polling algorithm to indicate the operation was suc-
cessful. However, a succeeding read will show that the
data is still “0”. Only erase operations can convert a “0”
to a “1”.
Note: See the appropriate Command Definitions table for
program command sequence.
Figure 2. Program Operation
Chip Erase Command Sequence
Chip erase is a six-bus-cycle operation. The chip erase
command sequence is initiated by writing two unlock
cycles, followed by a set-up command. Two additional
unlock write cycles are then followed by the chip erase
command, which in turn invokes the Embedded Erase
algorithm. The device does not require the system to
preprogram prior to erase. The Embedded Erase algo-
rithm automatically preprograms and verifies the entire
memory for an all zero data pattern prior to electrical
erase. The system is not required to provide any con-
trols or timings during these operations. The Command
Definitions table shows the address and data require-
ments for the chip erase command sequence.
Any commands written to the chip during the Embed-
ded Erase algorithm are ignored. Note that a hardware
reset during the chip erase operation immediately ter-
minates the operation. The Chip Erase command se-
quence should be reinitiated once the device has
returned to reading array data, to ensure data integrity.
The system can determine the status of the erase
operation by using DQ7, DQ6, DQ2, or RY/BY#. See
“Write Operation Status” for information on these
status bits. When the Embedded Erase algorithm is
complete, the device returns to reading array data
and addresses are no longer latched.
Figure 3 illustrates the algorithm for the erase opera-
tion. See the Erase/Program Operations tables in “AC
Characteristics” for parameters, and to the Chip/Sector
Erase Operation Timings for timing waveforms.
Sector Erase Command Sequence
Sector erase is a six bus cycle operation. The sector
erase command sequence is initiated by writing two un-
lock cycles, followed by a set-up command. Two addi-
tional unlock write cycles are then followed by the
address of the sector to be erased, and the sector
erase command. The Command Definitions table
shows the address and data requirements for the sec-
tor erase command sequence.
The device does not require the system to preprogram
the memory prior to erase. The Embedded Erase algo-
rithm automatically programs and verifies the sector for
an all zero data pattern prior to electrical erase. The
system is not required to provide any controls or tim-
ings during these operations.
After the command sequence is written, a sector erase
time-out of 50 µs begins. During the time-out period,
additional sector addresses and sector erase com-
mands may be written. Loading the sector erase buffer
may be done in any sequence, and the number of sec-
tors may be from one sector to all sectors. The time be-
tween these additional cycles must be less than 50 µs,
otherwise the last address and command might not be
accepted, and erasure may begin. It is recommended
that processor interrupts be disabled during this time to
ensure all commands are accepted. The interrupts can
be re-enabled after the last Sector Erase command is