S71GL064A08 SPANSION [SPANSION], S71GL064A08 Datasheet - Page 59

• Manufacturer Part Number: S71GL064A08
• Description: STACKED MULTI CHIP PRODUCT FLASH MEMORY AND RAM
• Manufacturer: SPANSION [SPANSION]

February 8, 2005 S71GL064A_00_A2
DQ2: Toggle Bit II
Reading Toggle Bits DQ6/DQ2
DQ5: Exceeded Timing Limits
The “Toggle Bit II” on DQ2, when used with DQ6, indicates whether a particular sector is ac-
tively erasing (that is, the Embedded Erase algorithm is in progress), or whether that sector
is erase-suspended. Toggle Bit II is valid after the rising edge of the final WE# pulse in the
command sequence.
DQ2 toggles when the system reads at addresses within those sectors that have been se-
lected for erasure. (The system may use either OE# or CE# to control the read cycles.) But
DQ2 cannot distinguish whether the sector is actively erasing or is erase-suspended. DQ6, by
comparison, indicates whether the device is actively erasing, or is in Erase Suspend, but can-
not distinguish which sectors are selected for erasure. Thus, both status bits are required for
sector and mode information. Refer to
Figure 8
II” explains the algorithm. See also the RY/BY#: Ready/Busy# subsection.
the toggle bit timing diagram.
graphical form.
Refer to
toggle bit status, it must read DQ7–DQ0 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 DQ7–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 operation. If it is still
toggling, the device did not completed the operation successfully, and the system must write
the reset command to return to reading array data.
The remaining scenario is that the system initially determines that the toggle bit is toggling
and DQ5 has not gone high. The system may continue to monitor the toggle bit and DQ5
through successive read cycles, determining the status as described in the previous para-
graph. 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 (top of
DQ5 indicates whether the program, erase, or write-to-buffer time has exceeded a specified
internal pulse count limit. Under these conditions DQ5 produces a “1,” indicating that the pro-
gram or erase cycle was not successfully completed.
The device may output a “1” on DQ5 if the system tries to program a “1” to a location that
was previously programmed to “0.” Only an erase operation can change a “0” back to a
“1.” Under this condition, the device halts the operation, and when the timing limit has been
exceeded, DQ5 produces a “1.”
In all these cases, the system must write the reset command to return the device to the read-
ing the array (or to erase-suspend-read if the device was previously in the erase-suspend-
program mode).
Figure 8
shows the toggle bit algorithm in flowchart form, and the section “DQ2: Toggle Bit
A d v a n c e
Figure
for the following discussion. Whenever the system initially begins reading
6).
I n f o r m a t i o n
S71GL064A based MCPs
Figure 21
Table 11
shows the differences between DQ2 and DQ6 in
to compare outputs for DQ2 and DQ6.
Figure 20
shows
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