curs, the chip erase command sequence should be
reinitiated once that bank has returned to reading
array data, to ensure data integrity. Note that the Se-
cured Silicon Sector, autoselect, and CFI functions are
unavailable when an erase operation is in progress.
START
Figure 5 illustrates the algorithm for the erase opera-
tion. Refer to the Erase and Program Operations ta-
bles in the AC Characteristics section for parameters,
and Figure 20 section for timing diagrams.
Write Program
Command Sequence
Sector Erase Command Sequence
Data Poll
from System
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 ad-
ditional unlock cycles are written, and are then fol-
lowed by the address of the sector to be erased, and
the sector erase command. Table 12 shows the ad-
dress and data requirements for the sector erase com-
mand sequence.
Embedded
Program
algorithm
in progress
Verify Data?
Yes
No
The device does not require the system to preprogram
prior to erase. The Embedded Erase algorithm auto-
matically programs and verifies the entire sector for an
all zero data pattern prior to electrical erase. The sys-
tem is not required to provide any controls or timings
during these operations.
No
Increment Address
Last Address?
Yes
Programming
Completed
After the command sequence is written, a sector erase
time-out of 80 µs occurs. 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 80
µs, otherwise erasure may begin. Any sector erase ad-
dress and command following the exceeded time-out
may or may not be accepted. It is recommended that
processor interrupts be disabled during this time to en-
sure all commands are accepted. The interrupts can
be re-enabled after the last Sector Erase command is
written. Any command other than Sector Erase or
Erase Suspend during the time-out period resets
that bank to the read mode. The system must rewrite
the command sequence and any additional addresses
and commands.
Note: See Table 12 for program command sequence.
Figure 4. Program Operation
Chip Erase Command Sequence
Chip erase is a six bus cycle operation. The chip 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 chip erase
command, which in turn invokes the Embedded Erase
algorithm. The device does not require the system to
preprogram prior to erase. The Embedded Erase algo-
rithm automatically preprograms and verifies the entire
memory for an all zero data pattern prior to electrical
erase. The system is not required to provide any con-
trols or timings during these operations. Table 12
shows the address and data requirements for the chip
erase command sequence.
The system can monitor DQ3 to determine if the sec-
tor erase timer has timed out (See the section on DQ3:
Sector Erase Timer.). The time-out begins from the ris-
ing edge of the final WE# or CE# pulse (first rising
edge) in the command sequence.
When the Embedded Erase algorithm is complete,
that bank returns to the read mode 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 the Write Operation Status sec-
tion for information on these status bits.
When the Embedded Erase algorithm is complete, the
bank returns to reading array data and addresses are
no longer latched. Note that while the Embedded
Erase operation is in progress, the system can read
data from the non-erasing bank. The system can de-
termine the status of the erase operation by reading
DQ7, DQ6, DQ2, or RY/BY# in the erasing bank. Refer
Any commands written during the chip erase operation
are ignored. However, note that a hardware reset im-
mediately terminates the erase operation. If that oc-
June 7, 2005
Am29DL640H
25
SPANSION [ SPANSION ]
