D a t a S h e e t
program set-up command. The program address and data are written next, which
in turn initiate the Embedded Program algorithm. The system is not required to
provide further controls or timings. The device automatically provides internally
generated program pulses and verifies the programmed cell margin. Table 5, on
page 25 shows the address and data requirements for the byte program com-
mand sequence.
When the Embedded Program algorithm is complete, the device then returns to
reading array data and addresses are no longer latched. The system can deter-
mine the status of the program operation by using DQ7, DQ6, or RY/BY#. See
Write Operation Status, on page 27 for information on these status bits.
Any commands written to the device during the Embedded Program Algorithm
are ignored. Note that a hardware reset immediately terminates the program-
ming operation. The program command sequence should be reinitiated once the
device resets to reading array data, to ensure data integrity.
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 shows that the data is
still 0. Only erase operations can convert a 0 to a 1.
Unlock Bypass Command Sequence
The unlock bypass feature allows the system to program 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 program command, A0h; the second
cycle contains the program address and data. Additional data is programmed in
the same manner. This mode dispenses with the initial two unlock cycles required
in the standard program command sequence, resulting in faster total program-
ming time. Table 5, on page 25 shows the requirements for the command
sequence.
During the unlock bypass mode, only the Unlock Bypass Program and Unlock By-
pass Reset commands are valid. To exit the unlock bypass mode, the system
must issue the two-cycle unlock bypass reset command sequence. The first cycle
must contain the data 90h; the second cycle the data 00h. Addresses are don’t
care for both cycles. The device then returns to reading array data.
Figure 3, on page 22 illustrates the algorithm for the program operation. See
Erase / Program Operations, on page 42 i for parameters, and Figure 17, on
page 43 for timing diagrams.
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