
February 23, 2005 S71AL016M_M0_A0
S71AL016M
33
A d v a n c e I n f o r m a t i o n
Figure 5, on page 35
illustrates the algorithm for the erase operation. See the
Table 18 on page 57
for parameters, and to
Figure 18, on page 57
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 addi-
tional unlock write cycles are then followed by the address of the sector to be
erased, and the sector erase command.
Table 10 on page 37
and
Table 11 on
page 43
show the address and data requirements for the sector erase command
sequence.
Note that the SecSi Sector, autoselect, and CFI functions are un-
available when an erase operation is in progress.
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 re-
quired 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 rec-
ommended 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 com-
mands 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 43
.) The time-out begins from the
rising edge of the final WE# pulse in the command sequence.
Once the sector erase operation begins, 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 returns 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 38
for information on these status bits.)
Figure 5, on page 35
illustrates the algorithm for the erase operation. Refer to
the
Table 18 on page 57
for parameters, and to
Figure 18, on page 52
for timing
diagrams.
Erase Suspend/Erase Resume Commands
The Erase Suspend command allows the system to interrupt a sector erase op-
eration 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