MBM29DL16XTE/BE70/90
DQ5 bit will indicate a “1.” Please note that this is not a device failure condition since the devices were incorrectly
used. If this occurs, reset 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.
See “Hardware Sequence Flags Table”.
• DQ2
Toggle Bit II
This toggle bit II, along with DQ6, can be used to determine whether the devices are 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
devices are in the erase-suspended-read mode, successive reads from the erase-suspended sector will cause
DQ2 to toggle. When the devices are 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:
For example, DQ2 and DQ6 can be used together to determine if the erase-suspend-read mode is in progress.
(DQ2 toggles while DQ6 does not.) See also “Toggle Bit Status Table” and “(9) DQ2 vs. DQ6” in ■TIMING
DIAGRAM.
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 an erasing sector.
To operate toggle bit function properly, CE or OE must be high when bank address is changed.
• Reading Toggle Bits DQ6/DQ2
Whenever the system initially begins reading toggle bit status, it must read DQ7 to DQ0 at least twice in a row to
determine whether a toggle bit is toggling. Typically a system would note and store the value of the toggle bit
after the first read. After the second read, the system would compare the new value of the toggle bit with the
first. If the toggle bit is not toggling, the device has completed the program or erase operation. The system can
read array data on DQ7 to DQ0 on the following read cycle.
However, if, after the initial two read cycles, the system determines that the toggle bit is still toggling, the system
also should note whether the value of DQ5 is high (see the section on “DQ5”). If it is, the system should then
determine again whether the toggle bit is toggling, since the toggle bit may have stopped toggling just as DQ5
went high. If the toggle bit is no longer toggling, the device has successfully completed the program or erase
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SPANSION [ SPANSION ]
