FLASH
AS29F040
is valid only during the sector erase operation,
including
the 50μs 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 Suspect 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 Suspect command.
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 addresss of the sector to be
erased, and the sector erase command. The Command
nitions table shows the address and data requirements for the
sector erase command sequence.
Defi-
When the Erase Suspect command is written during
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 50μs 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 sec-
tors. The time between these additional cycles must be less
than 50μs, 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 50μs, 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.
a
sector erase operation, the device requires a maximum of
20μs 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 erase operation.
After the erase operation has been suspected, the system
can read array data from any sector not selected for erasure.
(The device “erase suspends” all sectors selected for erasure.)
Normal read and write timings and command definitions ap-
ply. 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”
for information on these status bits.
FIGURE 2: 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.
Once the sector erase operation has begun, only the
Erase Suspend command is valid. All other commands are
ignored.
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” for information on these status bits.
Figure 2 illustrates the algorithm for the erase operation.
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.
Erase Suspend/Erase Resume Commands
NOTE:
The Erase Suspect command allows the system to
inter-
1) See the appropriate Command Definitions table for program command
sequence.
rupt a sector erase operation and then read data from, or program
data to, any sector not selected for erasure. This command
2) See “DQ3: Sector Erase Timer” for more information.
AS29F040
Micross Components reserves the right to change products or specifications without notice.
Rev. 2.3 01/10
8
MICROSS [ MICROSS COMPONENTS ]
