HY29F040A Datasheet, PDF (12/40 Pages) Hynix Semiconductor – 512K x 8-bit CMOS 5.0 volt-only, Sector Erase Flash Memory

next successive attempts. During Byte Programming,
the Toggle Bit is valid after the rising edge of the
fourth /WE pulse in the four write pulse
sequence. For Chip Erase, the Toggle Bit is valid
after the rising edge of the sixth /WE pulse in the
six write pulse sequence. For Sector Erase, the
Toggle Bit is valid after the last rising edge of the
sector erase /WE pulse. The Toggle Bit is also
active during the sector erase time-out win-
dow.
In Byte Programming, if the sector being written to is
protected, the Toggle Bit toggles for about 2 ms and
then stops toggling without the data having changed.
In Chip Erase or Sector Erase, the device will
erase all the selected sectors except for the ones
that are protected. If all selected sectors are pro-
tected, the chip will toggle the Toggle Bit for about
100 ms and then drop back into read mode, having
changed none of the data. Either /CE or /OE tog-
gling will cause the DQ6 Toggle Bit to toggle.
DQ5
Exceeded Timing Limits
DQ5 will indicate if Byte Programming, Chip Erase,
or Sector Erase time has exceeded the specified
limits (internal pulse count) of the device. Under
these conditions DQ5 will produce a logical “1”. This
is a failure condition that indicates the program or erase
cycle was not successfully completed. /Data Poll-
ing is the only operating function of the device under
this condition. The /OE and /WE pins will control
output disable functions as described in Table 1.
If this failure condition occurs during Sector Erase
operation, it indicates a particular sector is bad
and it may not be reused. However, other sectors
are still functional and may continue to be used
for the program or erase operation. To use other
sectors of the device, it must be reset to Read
mode. Write the Read/Reset command sequence
to the device, and then execute the Byte Program-
ming or Sector Erase command sequence. This
allows the system to continue to use the other
active sectors in the device.
Erase operation, it indicates the entire chip is bad
or combination of sectors are bad. In this situa-
tion, the chip should not be reused.
If this failure condition occurs during the Byte Pro-
gramming operation, it indicates the entire sector
containing that byte is bad and this sector may not
be reused (other sectors are still functional and can
be reused).
The DQ5 failure condition may also appear if a
user tries to program a non-blank location without
erasing. In this example, the device may exceed time
limits and not complete the Internal Algorithm op-
eration. Hence, the system never reads valid data
on DQ7 bit, and DQ6 never stops toggling. Once
the device has exceeded timing limits, the DQ5
bit will indicate a “1”.
DQ3
Sector Erase Timer
After the completion of the initial Sector Erase com-
mand sequence, the sector erase time-out win-
dow will begin. DQ3 will remain low until the time-
out window is closed. /Data Polling and Toggle Bit
are valid after the initial Sector Erase command
sequence.
If /Data Polling or the Toggle Bit indicates the de-
vice has been written with a valid erase
command, DQ3 may be used to determine if the
Sector Erase time-out window is still open. If DQ3
is a logical “1”, the internally controlled erase cycle
has begun. Attempts to write subsequent com-
mand to the device will be ignored until the erase
operation is completed as indicated by /Data Poll-
ing or Toggle Bit. If DQ3 is a logical ”0", the device
will accept additional Sector Erase commands.
To insure 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 were high on the second
status check, the command may not have been
accepted. Refer to Table 5: Write Operation Sta-
tus Flags.
If this failure condition occurs during the Chip
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HY29F040A