D A T A S H E E T
Temporary Sector Unprotect
HARDWARE DATA PROTECTION
This feature allows temporary unprotection of previ-
ously protected sectors to change data in-system. The
Sector Unprotect mode is activated by setting the RE-
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes (refer to Table 4 for com-
mand definitions). In addition, the following hardware
data protection measures prevent accidental erasure
or programming, which might otherwise be caused by
SET# pin to V . During this mode, formerly protected
ID
sectors can be programmed or erased by selecting the
sector addresses. Once V is removed from the RE-
ID
SET# pin, all the previously protected sectors are
protected again. Figure 2 shows the algorithm, and
Figure 23 shows the timing diagrams, for this feature.
spurious system level signals during V power-up and
power-down transitions, or from system noise.
CC
Low VCC Write Inhibit
When V
is less than V
, the device does not ac-
CC
LKO
cept any write cycles. This protects data during V
power-up and power-down. The command register and
all internal program/erase circuits are disabled, and the
CC
START
device resets. Subsequent writes are ignored until V
CC
RESET# = VID
(Note 1)
is greater than V
. The system must provide the
LKO
proper signals to the control pins to prevent uninten-
tional writes when V is greater than V
.
CC
LKO
Perform Erase or
Program Operations
Write Pulse “Glitch” Protection
Noise pulses of less than 5 ns (typical) on OE#, CE# or
WE# do not initiate a write cycle.
RESET# = VIH
Logical Inhibit
Write cycles are inhibited by holding any one of OE# =
Temporary Sector
Unprotect Completed
(Note 2)
V , CE# = V or WE# = V . To initiate a write cycle,
IL
IH
IH
CE# and WE# must be a logical zero while OE# is a
logical one.
Notes:
Power-Up Write Inhibit
1. All protected sectors unprotected.
If WE# = CE# = V and OE# = V during power up, the
IL
IH
2. All previously protected sectors are protected once
again.
device does not accept commands on the rising edge
of WE#. The internal state machine is automatically
reset to reading array data on power-up.
Figure 2. Temporary Sector Unprotect Operation
COMMAND DEFINITIONS
Writing specific address and data commands or se-
quences into the command register initiates device op-
erations. Table 4 defines the valid register command
sequences. Writing incorrect address and data val-
ues or writing them in the improper sequence resets
the device to reading array data.
retrieve data. The device is also ready to read array
data after completing an Embedded Program or Em-
bedded Erase algorithm.
After the device accepts an Erase Suspend com-
mand, the device enters the Erase Suspend mode.
The system can read array data using the standard
read timings, except that if it reads at an address
within erase-suspended sectors, the device outputs
status data. After completing a programming opera-
tion in the Erase Suspend mode, the system may
once again read array data with the same exception.
See “Erase Suspend/Erase Resume Commands” for
more information on this mode.
All addresses are latched on the falling edge of
WE# or CE#, whichever happens later. All data is
latched on the rising edge of WE# or CE#, whichever
happens first. Refer to the appropriate timing diagrams
in the AC Characteristics section.
Reading Array Data in Non-burst Mode
The device is automatically set to reading array data
after device power-up. No commands are required to
The system must issue the reset command to re-en-
able the device for reading array data if DQ5 goes high,
14
Am29BL802C
22371C7 November 3, 2006
SPANSION [ SPANSION ]
