EN29LV010 Datasheet, PDF (13/35 Pages) Eon Silicon Solution Inc. – 1 Megabit (128K x 8-bit ) Uniform Sector, CMOS 3.0 Volt-only Flash Memory

EN29LV010
The DQ5 failure condition may appear if the system tries to program a “1” to a location that is
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 operation has exceeded the timing limits,
DQ5 produces a “1.” Under both these conditions, the system must issue the reset command to
return the device to reading array data.
DQ3: Sector Erase Timer
After writing a sector erase command sequence, the output on DQ3 can be used to determine
whether or not an erase operation has begun. (The sector erase timer does not apply to the chip
erase command.) When sector erase starts, DQ3 switches from “0” to “1.” This device does not
support multiple sector erase command sequences so it is not very meaningful since it immediately
shows as a “1” after the first 30h command. Future devices may support this feature.
DQ2: Erase Toggle Bit II
The “Toggle Bit” on DQ2, when used with DQ6, indicates whether a particular 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. (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 cannot
distinguish which sectors are selected for erasure. Thus, both status bits are required for sector and
mode information. Refer to Table 5 to compare outputs for DQ2 and DQ6.
Flowchart 6 shows the toggle bit algorithm, and the section “DQ2: Toggle Bit” explains the algorithm.
See also the “DQ6: Toggle Bit I” subsection. Refer to the Toggle Bit Timings figure for the toggle bit
timing diagram. The DQ2 vs. DQ6 figure shows the differences between DQ2 and DQ6 in graphical
form.
Reading Toggle Bits DQ6/DQ2
Refer to Flowchart 6 for the following discussion. 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.
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–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 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 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 (top of Flowchart 6).
This Data Sheet may be revised by subsequent versions ₁₃ ©2003 Eon Silicon Solution, Inc., www.essi.com.tw
or modifications due to changes in technical specifications.
Rev. B, Issue Date: 2004/01/05