P R E L I M I N A R Y
Any commands written to the device during the Em-
Chip Erase Command Sequence
bedded Program Algorithm are ignored. Note that a
hardware reset immediately terminates the program-
ming operation. The Byte Program command se-
quence should be reinitiated once the device has reset
to reading array data, to ensure data integrity.
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 5 shows
the address and data requirements for the chip erase
command sequence.
Programming is allowed in any sequence and across
sector boundaries. A bit cannot be programmed
from a “0” back to a “1”. Attempting to do so may halt
the operation and set DQ5 to “1”, or cause the Data#
Polling algorithm to indicate the operation was suc-
cessful. However, a succeeding read will show that the
data is still “0”. Only erase operations can convert a “0”
to a “1”.
Figure 2 illustrates the algorithm for the program oper-
ation. See the Erase/Program Operations table in “AC
Characteristics” for parameters, and to Figure 16 for
timing diagrams.
Any commands written to the chip during the Embed-
ded Erase algorithm are ignored. Note that a hardware
reset during the chip erase operation immediately ter-
minates the operation. The Chip Erase command se-
quence should be reinitiated once the device has
returned to reading array data, to ensure data integrity.
The system can determine the status of the erase op-
eration by using DQ7, DQ6, DQ2, or RY/BY#. See
“Write Operation Status” for information on these sta-
tus bits. When the Embedded Erase algorithm is com-
plete, the device returns to reading array data and
addresses are no longer latched.
START
Write Program
Command Sequence
Figure 3 illustrates the algorithm for the erase opera-
tion. See the Erase/Program Operations tables in “AC
Characteristics” for parameters, and to Figure 17 for
timing diagrams.
Data Poll
from System
Embedded
Program
algorithm
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 ad-
ditional unlock write cycles are then followed by the ad-
dress of the sector to be erased, and the sector erase
command. Table 5 shows the address and data re-
quirements for the sector erase command sequence.
in progress
Verify Data?
No
Yes
No
The device does not require the system to preprogram
the memory prior to erase. The Embedded Erase algo-
rithm 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 tim-
ings during these operations.
Increment Address
Last Address?
Yes
Programming
Completed
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 sec-
tors may be from one sector to all sectors. The time be-
tween 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
20514C-6
Note: See Table 5 for program command sequence.
Figure 2. Program Operation
Am29LV400
14
CYPRESS [ CYPRESS ]
