MX29LV160C T/B
Toggle Bit I may be read at any address, and is valid
after the rising edge of the final WE# or CE#, whichever
happens first, in the command sequence (prior to the
program or erase operation), and during the sector time-
out.
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 com-
parison, indicates whether the device is actively eras-
ing, or is in Erase Suspend, but cannot distinguish which
sectors are selected for erasure. Thus, both status bits
are required for sectors and mode information. Refer to
Table 7 to compare outputs for Q2 and Q6.
During an Automatic Program or Erase algorithm opera-
tion, successive read cycles to any address cause Q6
to toggle. The system may use either OE# or CE# to
control the read cycles.When the operation is complete,
Q6 stops toggling.
ReadingToggle Bits Q6/ Q2
After an erase command sequence is written, if all sec-
tors 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.
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 com-
pleted the program or erase operation. The system can
read array data on Q7-Q0 on the following read cycle.
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.
However, if after the initial two read cycles, the system
determines that the toggle bit is still toggling, the sys-
tem 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 opera-
tion. 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.
If a program address falls within a protected sector, Q6
toggles for approximately 2 us 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 algorithm
is complete.
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 sta-
tus 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 al-
gorithm when it returns to determine the status of the
operation.
Table 8 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 II is valid
after the rising edge of the final WE# or CE#, whichever
happens first, in the command sequence.
Q5 : ExceededTiming 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
indicates that the program or erase cycle was not suc-
Q2 toggles when the system reads at addresses within
those sectors that have been selected for erasure. (The
P/N:PM1186
REV. 1.2, JAN. 19, 2006
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