D A T A S H E E T
Any commands written to the chip during the Embed-
Timer” section.) The time-out begins from the rising
edge of the final WE# pulse in the command sequence.
ded Erase algorithm are ignored. Note that a hardware
reset during the chip erase operation immediately ter-
minates the operation. The Chip Erase command
sequence should be reinitiated once the device has re-
turned to reading array data, to ensure data integrity.
Once the sector erase operation has begun, only the
Erase Suspend command is valid. All other commands
are ignored. Note that a hardware reset during the
sector erase operation immediately terminates the op-
eration. The Sector Erase command sequence 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.
When the Embedded Erase algorithm is complete, the
device returns to reading array data and addresses are
no longer latched. The system can determine the sta-
tus of the erase operation by using DQ7, DQ6, DQ2, or
RY/BY#. Refer to “Write Operation Status” for informa-
tion on these status bits.
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.
Figure 3 illustrates the algorithm for the erase opera-
tion. Refer to the Erase/Program Operations tables in
the “AC Characteristics” section for parameters, and to
the Sector Erase Operations Timing diagram 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
additional 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.
Erase Suspend/Erase Resume Commands
The Erase Suspend command allows the system to in-
terrupt a sector erase operation and then read data
from, or program data to, any sector not selected for
erasure. This command is valid only during the sector
erase operation, including the 50 µs time-out period
during the sector erase command sequence. The
Erase Suspend command is ignored if written during
the chip erase operation or Embedded Program algo-
rithm. Writing the Erase Suspend command during the
Sector Erase time-out immediately terminates the
time-out period and suspends the erase operation. Ad-
dresses are “don’t-cares” when writing the Erase
Suspend command.
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
between 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 recom-
mended that processor interrupts be disabled during
this time to ensure all commands are accepted. The in-
terrupts can be re-enabled after the last Sector Erase
command is written. If the time between additional sec-
tor erase commands can be assumed to be less than
50 µs, the system need not monitor DQ3. Any com-
mand other than Sector Erase or Erase Suspend
during the time-out period resets the device to
reading array data. The system must rewrite the com-
mand sequence and any additional sector addresses
and commands.
When the Erase Suspend command is written during a
sector erase operation, the device requires a maximum
of 20 µs to suspend the erase operation. However,
when the Erase Suspend command is written during
the sector erase time-out, the device immediately ter-
minates the time-out period and suspends the erase
operation.
After the erase operation has been suspended, the
system can read array data from or program data to
any sector not selected for erasure. (The device “erase
suspends” all sectors selected for erasure.) Normal
read and write timings and command definitions apply.
Reading at any address within erase-suspended sec-
tors produces status data on DQ7–DQ0. The system
can use DQ7, or DQ6 and DQ2 together, to determine
if a sector is actively erasing or is erase-suspended.
See “Write Operation Status” for information on these
status bits.
The system can monitor DQ3 to determine if the sector
erase timer has timed out. (See the “DQ3: Sector Erase
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