MBM29F800TA-55/-70/-90/MBM29F800BA-55/-70/-90
The DQ5 failure condition may also appear if a user tries to program a non blank location without erasing. In this
case the device locks out and never complete the Embedded Algorithm operation. Hence, the system never
reads a valid data on DQ7 bit and DQ6 never stops toggling. Once the device has exceeded timing limits, the
DQ5 bit will indicate a “1.” Please note that this is not a device failure condition since the device was incorrectly
used. If this occurs, rest the device with command sequence.
DQ3
Sector Erase Timer
After the completion of the initial sector erase command sequence the sector erase time-out will begin. DQ3 will
remain low until the time-out is complete. Data Polling and Toggle Bit are valid after the initial sector erase
command sequence.
If Data Polling or the Toggle Bit I indicates the device has been written with a valid erase command, DQ3 may
be used to determine if the sector erase timer window is still open. If DQ3 is high (“1”) the internally controlled
erase cycle has begun; attempts to write subsequent commands to the device will be ignored until the erase
operation is completed as indicated by Data Polling or Toggle Bit I. If DQ3 is low (“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 8: Hardware Sequence Flags.
DQ2
Toggle Bit II
This toggle bit II, along with DQ6, can be used to determine whether the device is in the Embedded Erase
Algorithm or in Erase Suspend.
Successive reads from the erasing sector will cause DQ2 to toggle during the Embedded Erase Algorithm. If the
device is in the erase-suspended-read mode, successive reads from the erase-suspended sector will cause DQ2
to toggle. When the device is in the erase-suspended-program mode, successive reads from the byte address
of the non-erase suspended sector will indicate a logic “1” at the DQ2 bit.
DQ6 is different from DQ2 in that DQ6 toggles only when the standard program or Erase, or Erase Suspend
Program operation is in progress. The behavior of these two status bits, along with that of DQ7, is summarized
as follows:
Mode
DQ7
DQ7
0
DQ6
DQ2
1
Program
Erase
toggles
toggles
toggles
Erase Suspend Read
(Erase-Suspended Sector)
(Note 1)
1
1
toggles
Erase Suspend Program
DQ7 (Note 2)
toggles
1 (Note 2)
Notes: 1. These status flags apply when outputs are read from a sector that has been erase-suspended.
2. Thesestatusflagsapplywhenoutputsarereadfromthebyteaddressofthenon-erasesuspendedsector.
For example, DQ2 and DQ6 can be used together to determine the erase-suspend-read mode (DQ2 toggles while
DQ6 does not). See also Table 8 and Figure 22.
Furthermore, DQ2 can also be used to determine which sector is being erased. When the device is in the erase
mode, DQ2 toggles if this bit is read from the erasing sector.
20
FUJITSU [ FUJITSU ]
