COTS PEM
BOOT SECTOR FLASH
Austin Semiconductor, Inc.
AS29LV016J
DQ5: EXCEEDED TIMING LIMITS
DQ5 indicates whether the program or erase time has
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.
The DQ5 failure condition may appear if the system tries
to program a 1 to a location that is previously programmed
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 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.
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 accepted the
command sequence, and then read DQ3. If DQ3 is 1, the
internally controlled erase cycle has begun; all further
commands (other than Erase Suspend) 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 following
each subsequent sector erase command. If DQ3 is high
on the second status check, the last command might
not have been accepted. Table 10 shows the outputs for
DQ3.
DQ3: SECTOR ERASE TIMER
After writing a sector erase command sequence, the
system may read DQ3 to determine 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 command. 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 on page 19.
Table 10: Write Operation Status
Operation
Standard Embedded Program Algorithm
Mode Embedded Erase Algorithm
Reading within Erase
Erase Suspended Sector
Suspend Reading within Non-Erase
Mode Suspended Sector
Erase-Suspend-Program
DQ72
DQ7#
0
1
DQ6
Toggle
Toggle
No Toggle
DQ11
0
0
0
Data
DQ7#
Data
Toggle
Data
0
DQ3
N/A
1
N/A
DQ22 RY/BY#
No Toggle 0
Toggle
0
Toggle
1
Data
Data
1
N/A
N/A
0
Notes:
1. DQ5 switches to 1 when and 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.
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Rev. 0.0 02/09
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