D A T A S H E E T
DQ7, DQ6, or RY/BY#. See “Write Operation Status”
for information on these status bits.
Any commands written to the device during the Em-
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.
START
Write Program
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
successful. However, a succeeding read will show that
the data is still “0”. Only erase operations can convert
a “0” to a “1”.
Data Poll
from System
Embedded
Program
algorithm
in progress
Verify Data?
Yes
No
Unlock Bypass Command Sequence
The unlock bypass feature allows the system to pro-
gram bytes or words to the device faster than using the
standard program command sequence. The unlock
bypass command sequence is initiated by first writing
two unlock cycles. This is followed by a third write
cycle containing the unlock bypass command, 20h.
The device then enters the unlock bypass mode. A
two-cycle unlock bypass program command sequence
is all that is required to program in this mode. The first
cycle in this sequence contains the unlock bypass pro-
gram command, A0h; the second cycle contains the
program address and data. Additional data is pro-
grammed in the same manner. This mode dispenses
with the initial two unlock cycles required in the stan-
dard program command sequence, resulting in faster
total programming time. Table 5 shows the require-
ments for the command sequence.
No
Increment Address
Last Address?
Yes
Programming
Completed
Note: See Table 5 for program command sequence.
Figure 3. Program Operation
During the unlock bypass mode, only the Unlock By-
pass Program and Unlock Bypass Reset commands
are valid. To exit the unlock bypass mode, the system
must issue the two-cycle unlock bypass reset com-
mand sequence. The first cycle must contain the pro-
gram address and the data 90h. The second cycle
need only contain the data 00h. The device then re-
turns to reading array data.
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 5 shows
the address and data requirements for the chip erase
command sequence.
Figure 3 illustrates the algorithm for the program oper-
ation. See the Erase/Program Operations table in “AC
Characteristics” for parameters, and to Figure 17 for
timing diagrams.
Any commands written to the chip during the Embed-
ded Erase algorithm are ignored. Note that a hard-
ware reset during the chip erase operation
immediately terminates the operation. The Chip Erase
command sequence should be reinitiated once the de-
16
Am29LV400B
21523D4 December 4, 2006
SPANSION [ SPANSION ]
