D A T A S H E E T
from “0” back to a “1.” Attempting to do so may
Enter Secured Silicon™ Sector/Exit
Secured Silicon Sector Command
Sequence
cause that bank to set DQ5 = 1, or cause the DQ7 and
DQ6 status bits to indicate the operation was success-
ful. However, a succeeding read will show that the
data is still “0.” Only erase operations can convert a “0”
to a “1.”
The system can access the Secured Silicon Sector re-
gion by issuing the three-cycle Enter Secured Silicon
Sector command sequence. The device continues to
access the Secured Silicon Sector region until the sys-
tem issues the four-cycle Exit Secured Silicon Sector
command sequence. The Exit Secured Silicon Sector
command sequence returns the device to normal op-
eration. Table 14 shows the address and data
requirements for both command sequences. See also
“Secured Silicon Sector Flash Memory Region” for fur-
ther information. Note that a hardware reset
(RESET#=VIL) will reset the device to reading array
data.
Unlock Bypass Command Sequence
The unlock bypass feature allows the system to pro-
gram bytes or words to a bank 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 14 shows the require-
ments for the command sequence.
Byte/Word Program Command Sequence
The system may program the device by word or byte,
depending on the state of the BYTE# pin. Program-
ming is a four-bus-cycle operation. The program
command sequence is initiated by writing two unlock
write cycles, followed by the program set-up com-
mand. The program address and data are written next,
which in turn initiate the Embedded Program algo-
rithm. 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 14 shows the address
and data requirements for the byte program command
sequence.
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 device then returns to reading
array data.
The device offers accelerated program operations
through the WP#/ACC pin. When the system asserts
When the Embedded Program algorithm is complete,
that bank then returns to reading array data and ad-
dresses are no longer latched. The system can
determine the status of the program operation by
using DQ7, DQ6, or RY/BY#. Refer to the Write Oper-
ation Status section for information on these status
bits.
V
HH on the WP#/ACC pin, the device automatically en-
ters the Unlock Bypass mode. The system may then
write the two-cycle Unlock Bypass program command
sequence. The device uses the higher voltage on the
WP#/ACC pin to accelerate the operation. Note that
the WP#/ACC pin must not be at VHH any operation
other than accelerated programming, or device dam-
age may result. In addition, the WP#/ACC pin must not
be left floating or unconnected; inconsistent behavior
of the device may result.
Any commands written to the device during the Em-
bedded Program Algorithm are ignored. Note that a
hardware reset immediately terminates the program
operation. The program command sequence should
be reinitiated once that bank has returned to reading
array data, to ensure data integrity.
Figure 3 illustrates the algorithm for the program oper-
ation. Refer to the Erase and Program Operations
table in the AC Characteristics section for parameters,
and Figure 17 for timing diagrams.
Programming is allowed in any sequence and across
sector boundaries. A bit cannot be programmed
26
Am29DL16xD
21533E6 February 26, 2009
SPANSION [ SPANSION ]
