change a “0” back to a “1.” Under this condition, the device halts the opera-
tion, and when the operation has exceeded the timing limits, DQ5 produces a “1.”
Under both these conditions, the system must issue the reset command to return
the device to reading array data.
DQ3: Sector Erase Timer
After writing a sector erase command sequence, the system may read DQ3 to de-
termine whether or not an erase operation has begun. (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.” The system
may ignore DQ3 if the system can guarantee that the time between additional
sector erase commands will always be less than 50 µs. See also the “Sector
Erase Command Sequence” section.
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 has ac-
cepted the command sequence, and then read DQ3. If DQ3 is “1”, the internally
controlled erase cycle has begun; all further commands (other than Erase Sus-
pend) are ignored until the erase operation is complete. If DQ3 is “0”, the device
will accept additional sector erase commands. To ensure the command has been
accepted, the system software should check the status of DQ3 prior to and fol-
lowing each subsequent sector erase command. If DQ3 is high on the second
status check, the last command might not have been accepted. Table 12 shows
the outputs for DQ3.
Table 12. Write Operation Status
DQ7
(Note
2)
DQ5
(Note 1)
DQ2
(Note 2)
Operation
DQ6
DQ3
N/A
1
RY/BY#
Embedded Program Algorithm
Embedded Erase Algorithm
Program-
Program-
Suspend Read
DQ7#
0
Toggle
Toggle
0
0
No toggle
Toggle
0
0
Standard
Mode
Invalid (not allowed)
Data
1
1
1
Program
Suspend
Mode
Suspended Sector
Non-Program
Suspended Sector
Reading within Erase
Suspended Sector
1
No toggle
0
N/A
Toggle
Erase
Suspend Reading within Non-Erase Suspended
Data
Data
Data
0
Data
N/A
Data
N/A
1
0
Mode
Sector
Erase-Suspend-Program
DQ7#
Toggle
Notes:
1. DQ5 switches to ‘1’ when an Embedded Program or Embedded Erase operation has exceeded the maximum timing
limits. See “DQ5: Exceeded Timing Limits” for more information.
2. DQ7 and DQ2 require a valid address when reading status information. Refer to the appropriate subsection for further
details.
39
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