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 10.1 on page 30 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
algorithm 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 commands 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 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
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 35.) The time-out begins from the rising edge of the final WE# pulse in the command
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, DQ2,
or RY/BY#. (Refer to Write Operation Status on page 31 for information on these status bits.)
Figure 9.2 on page 29 illustrates the algorithm for the erase operation. Refer to Erase/Program Operations
on page 43 for parameters, and to Figure 17.6 on page 44 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 algorithm.
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
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 terminates the time-out period and suspends the
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 sectors
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 on page 31 for information on
these status bits.
After an erase-suspended program operation is complete, 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 on page 31 for more
S29AL016D_00_A8 February 27, 2009