P R E L I M I N A R Y
ensure all commands are accepted. The interrupts can
time-out period and suspends the erase operation. Ad-
dresses are “don’t-cares” when writing the Erase Sus-
pend command.
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.
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.
The system can monitor DQ3 to determine if the sector
erase timer has timed out. (See the “DQ3: Sector Erase
Timer” section.) The time-out begins from the rising
edge of the final WE# pulse in the command sequence.
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.
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.
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.)
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 operation.
See “Write Operation Status” for more information.
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
Figure 17 for timing diagrams.
The system may also write the autoselect command
sequence when the device is in the Erase Suspend
mode. The device allows reading autoselect codes
even at addresses within erasing sectors, since the
codes are not stored in the memory array. When the
device exits the autoselect mode, the device reverts to
the Erase Suspend mode, and is ready for another
valid operation. See “Autoselect Command Sequence”
for more information.
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
The system must write the Erase Resume command
(address bits are “don’t care”) to exit the erase suspend
mode and continue the sector erase operation. Further
writes of the Resume command are ignored. Another
Erase Suspend command can be written after the de-
vice has resumed erasing.
15
Am29LV400
CYPRESS [ CYPRESS ]
