D A T A S H E E T
device did not completed the operation successfully,
to and following each subsequent sector erase com-
mand. If DQ3 is high on the second status check, the
last command might not have been accepted. Table 13,
on page 30 shows the outputs for DQ3.
and the system must write the reset command to return
to reading array data.
The remaining scenario is that the system initially
determines that the toggle bit is toggling and DQ5 is not
high. The system may continue to monitor the toggle bit
and DQ5 through successive read cycles, determining
the status as described in the previous paragraph.
Alternatively, it may choose to perform other system
tasks. In this case, the system must start at the begin-
ning of the algorithm when it returns to determine the
status of the operation (top of Figure 6).
START
Read DQ7–DQ0
(Note 1)
DQ5: Exceeded Timing Limits
DQ5 indicates whether the program or erase time
exceeded a specified internal pulse count limit. Under
these conditions DQ5 produces a “1.” This is a failure
condition that indicates the program or erase cycle was
not successfully completed.
Read DQ7–DQ0
The DQ5 failure condition may appear if the system
tries to program a “1” to a location that is previously pro-
grammed to “0.” Only an erase operation can change
a “0” back to a “1.” Under this condition, the device
halts the operation, and when the operation exceeds
the timing limits, DQ5 produces a “1.”
No
Toggle Bit
= Toggle?
Yes
No
DQ5 = 1?
Yes
Under both these conditions, the system must issue the
reset command to return the device to reading array
data.
DQ3: Sector Erase Timer
(Notes
1, 2)
Read DQ7–DQ0
Twice
After writing a sector erase command sequence, the
system may read DQ3 to determine whether or not an
erase operation began. (The sector erase timer does
not apply to the chip erase command.) If additional
sectors are selected for erasure, the entire time-out
also applies after each additional sector erase com-
mand. When the time-out is complete, DQ3 switches
from “0” to “1.” If the time between additional sector
erase commands from the system are assumed to be
less than 50 μs, the system need not monitor DQ3. See
also the “Sector Erase Command Sequence” on
page 24.
Toggle Bit
= Toggle?
No
Yes
Program/Erase
Operation Not
Complete, Write
Reset Command
Program/Erase
Operation Complete
After the sector erase command sequence is written,
the system should read the status on DQ7 (Data#
Polling) or DQ6 (Toggle Bit I) to ensure the device
accepted the command sequence, and then read DQ3.
If DQ3 is “1”, the internally controlled erase cycle
started; all further commands (other than Erase Sus-
pend) are ignored until the erase operation is complete.
If DQ3 is “0”, the device accepts additional sector erase
commands. To ensure the command is accepted, the
system software should check the status of DQ3 prior
Notes:
1. Read toggle bit twice to determine whether or not it is
toggling. See text.
2. Recheck toggle bit because it may stop toggling as DQꢀ
changes to “1”. See text.
Figure 6. Toggle Bit Algorithm
January 23, 2007 21635C5
Am29SL160C
29
AMD [ AMD ]
