S29PL-N Datasheet, PDF (42/85 Pages) SPANSION – 256/128/128 Mb (16/8/8 M x 16-Bit) CMOS, 3.0 Volt-only Simultaneous Read/Write, Page-Mode Flash Memory

Preliminary
DQ6: Toggle Bit I . Toggle Bit I on DQ6 indicates whether an Embedded Program or Erase algo-
rithm is in progress or complete, or whether the device has entered the Erase Suspend mode.
Toggle Bit I can be read at any address in the same bank, and is valid after the rising edge of the
final WE# pulse in the command sequence (prior to the program or erase operation), and during
the sector erase time-out.
During an Embedded Program or Erase algorithm operation, successive read cycles to any ad-
dress cause DQ6 to toggle. When the operation is complete, DQ6 stops toggling.
After an erase command sequence is written, if all sectors selected for erasing are protected, DQ6
toggles for approximately t_ASP (all sectors protected toggle time), then returns to reading array
data. If not all selected sectors are protected, the Embedded Erase algorithm erases the unpro-
tected sectors, and ignores the selected sectors that are protected.
The system can use DQ6 and DQ2 together to determine whether a sector is actively erasing or
is erase-suspended. When the device is actively erasing (that is, the Embedded Erase algorithm
is in progress), DQ6 toggles. When the device enters the Erase Suspend mode, DQ6 stops tog-
gling. However, the system must also use DQ2 to determine which sectors are erasing or erase-
suspended. Alternatively, the system can use DQ7, see DQ7: Data# Polling.
If a program address falls within a protected sector, DQ6 toggles for approximately t_PAP after the
program command sequence is written, then returns to reading array data.
DQ6 also toggles during the erase-suspend-program mode, and stops toggling once the Embed-
ded Program Algorithm is complete.
See the following for additional information: Figure 7.4, Write Operation Status Flowchart,
Figure 11.14, Toggle Bit Timings (During Embedded Algorithms), Table 7.18, Write Operation
Status, and Figure 11.15, DQ2 vs. DQ6.
Toggle Bit I on DQ6 requires either OE# or CE# to be de-asserted and reasserted to show the
change in state.
DQ2: Toggle Bit II . The Toggle Bit II on DQ2, when used with DQ6, indicates whether a partic-
ular sector is actively 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 selected for erasure. But DQ2 cannot distinguish whether the sector is actively
erasing or is erase-suspended. DQ6, by comparison, 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 sector and mode information. Refer to Table 7.18, Write Opera-
tion Status to compare outputs for DQ2 and DQ6. See the following for additional information:
Figure 7.4, Write Operation Status Flowchart and Figure 11.14, Toggle Bit Timings (During Em-
bedded Algorithms).
Reading Toggle Bits DQ6/DQ2. Whenever the system initially begins reading toggle bit status,
it must read DQ7 – DQ0 at least twice in a row to determine whether a toggle bit is toggling. Typ-
ically, 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 erases 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 deter-
mine again whether the toggle bit is toggling, since the toggle bit might have stopped toggling
just as DQ5 went high. If the toggle bit is no longer toggling, the device has successfully com-
pleted the program or erases 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 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
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S29PL-N MirrorBit™ Flash Family
S29PL-N_00_A4 November 23, 2005