MX29F200CT Macronix International, MX29F200CT Datasheet - Page 12

• Manufacturer Part Number: MX29F200CT
• Description: 2M-BIT [256Kx8/128Kx16] CMOS FLASH MEMORY
• Manufacturer: Macronix International

After an erase command sequence is written, if all
sectors selected for erasing are protected, Q6 toggles
and returns to reading array data. If not all selected
sectors are protected, the Automatic Erase algorithm
erases the unprotected sectors, and ignores the selected
sectors that are protected.
The system can use Q6 and Q2 together to determine
whether a sector is actively erasing or is erase sus-
pended. When the device is actively erasing (that is, the
Automatic Erase algorithm is in progress), Q6 toggling.
When the device enters the Erase Suspend mode, Q6
stops toggling. However, the system must also use Q2
to determine which sectors are erasing or erase-sus-
pended. Alternatively, the system can use Q7.
If a program address falls within a protected sector, Q6
toggles for approximately 2us after the program com-
mand sequence is written, then returns to reading array
data.
Q6 also toggles during the erase-suspend-program mode,
and stops toggling once the Automatic Program algo-
rithm is complete.
Table 4 shows the outputs for Toggle Bit I on Q6.
Q2:Toggle Bit II
The "Toggle Bit II" on Q2, when used with Q6, indicates
whether a particular sector is actively erasing (that is, the
Automatic Erase algorithm is in process), or whether that
sector is erase-suspended. Toggle Bit I is valid after the
rising edge of the final WE# pulse in the command
sequence.
Q2 toggles when the system reads at addresses within
those sectors that have been selected for erasure. (The
system may use either OE# or CE# to control the read
cycles.) But Q2 cannot distinguish whether the sector is
actively erasing or is erase-suspended. Q6, by compari-
son, indicates whether the device is actively erasing, or
is in Erase Suspend, but cannot distinguish which sec-
tors are selected for erasure. Thus, both status bits are
required for sectors and mode information. Refer to Table
4 to compare outputs for Q2 and Q6.
P/N:PM1250
12
Reading Toggle Bits Q6/ Q2
Whenever the system initially begins reading toggle bit
status, it must read Q7-Q0 at least twice in a row to
determine whether a toggle bit is toggling. Typically, the
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 Q7-Q0 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 Q5 is high (see the
section on Q5). 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 Q5 went high. If the
toggle bit is no longer toggling, the device has successfully
completed the program or erase operation. If it is still
toggling, the device did not complete the operation
successfully, and the system must write the reset
command to return to reading array data.
The remaining scenario is that system initially determines
that the toggle bit is toggling and Q5 has not gone high.
The system may continue to monitor the toggle bit and
Q5 through successive read cycles, determining the
status as described in the previous paragraph.
Alternatively, it may choose to perform other system
tasks. In this case, the system must start at the beginning
of the algorithm when it returns to determine the status of
the operation.
Q5
Exceeded Timing Limits
Q5 will indicate if the program or erase time has exceeded
the specified limits(internal pulse count). Under these
conditions Q5 will produce a "1". This time-out condition
which indicates that the program or erase cycle was not
successfully completed. Data# Polling and Toggle Bit
are the only operating functions of the device under this
condition.
If this time-out condition occurs during sector erase
operation, it specifies that a particular sector is bad and
it may not be reused. However, other sectors are still
functional and may be used for the program or erase
MX29F200C T/B
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REV. 1.0 , DEC. 14, 2005