May 5, 2006 21557F4
Am29LV001B
15
D A T A S H E E T
device has returned to reading array data, to ensure
data integrity.
The system can determine the status of the erase oper-
ation by using DQ7, DQ6, or DQ2. See
“Write
Operation Status” on page 18
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 4, on page 16
illustrates the algorithm for the
erase operation. See the tables
“Erase/Program Oper-
ations” on page 28
for parameters, and
Figure 16, on
page 30
for timing diagrams.
Sector Erase Command Sequence
Sector erase is a six bus cycle operation. The sector
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
address of the sector to be erased, and the sector
erase command.
Table 5 on page 17
shows the
address and data requirements for the sector 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
timings 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
sectors 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
interrupts can be re-enabled after the last Sector Erase
command is written. If the time between additional
sector erase commands can be assumed to be less
than 50 μs, the system need not monitor DQ3. Any
command other than Sector Erase or Erase Suspend
during the time-out period resets the device to reading
array data. The system must rewrite the command
sequence and any additional sector addresses and
commands.
The system can monitor DQ3 to determine if the sector
erase timer has timed out. (See
“DQ3: Sector Erase
Timer” on page 20
.) The time-out begins from the rising
edge of the final WE# pulse in the command sequence.
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
operation. The Sector Erase command sequence
should be reinitiated once the device has returned to
reading array data, to ensure data integrity.
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
status of the erase operation by using DQ7, DQ6, or
DQ2. (Refer to
“Write Operation Status” on page 18
for
information on these status bits.)
Figure 4
illustrates the algorithm for the erase opera-
tion. Refer to the tables
“Erase/Program Operations”
on page 28
for parameters, and
Figure 16, on page 30
for timing diagrams.
Erase Suspend/Erase Resume Commands
The Erase Suspend command allows the system to
interrupt 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.
Addresses are “don’t-cares” when writing the Erase
Suspend command.
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
system can use DQ7, or DQ6 and DQ2 together, to
determine if a sector is actively erasing or is erase-sus-
pended. See
“Write Operation Status” on page 18
for
information on these status bits.
After an erase-suspended program operation is com-
plete, the system can once again read array data within
non-suspended sectors. The system can determine
the status of the program operation using the DQ7 or
DQ6 status bits, just as in the standard program oper-
ation. See
“Write Operation Status” on page 18
for
more information.