EN29LV160B Datasheet, PDF (18/43 Pages) Eon Silicon Solution Inc. – 16 Megabit (2048K x 8-bit / 1024K x 16-bit) Flash Memory

DQ6
Toggle Bit I
EN29LV160B
The EN29LV160B provides a “Toggle Bit” on DQ6 to indicate the status of the embedded programming
and erase operations. (See Table 6)
During an embedded Program or Erase operation, successive attempts to read data from the device at
any address (by active OE# or CE#) will result in DQ6 toggling between “zero” and “one”. Once the
embedded Program or Erase operation is completed, DQ6 will stop toggling and valid data will be read
on the next successive attempts. During embedded Programming, the Toggle Bit is valid after the rising
edge of the fourth WE# pulse in the four-cycle sequence. During Erase operation, the Toggle Bit is valid
after the rising edge of the sixth WE# pulse for sector erase or chip erase.
In embedded Programming, if the sector being written to is protected, DQ6 will toggles for about 2 μs,
then stop toggling without the data in the sector having changed. In Sector Erase or Chip Erase, if all
selected sectors are protected, DQ6 will toggle for about 100 μs. The chip will then return to the read
mode without changing data in all protected sectors.
The flowchart for the Toggle Bit (DQ6) is shown in Flowchart 6. The Toggle Bit timing diagram is shown
in Figure 9.
DQ5 Exceeded Timing Limits
DQ5 indicates whether the program or erase time has exceeded a specified internal pulse count limit.
Under these conditions DQ5 produces a “1.” This is a failure condition that indicates the program or
erase cycle was not successfully completed. Since it is possible that DQ5 can become a 1 when the
device has successfully completed its operation and has returned to read mode, the user must check
again to see if the DQ6 is toggling after detecting a “1” on DQ5.
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.
This Data Sheet may be revised by subsequent versions
18
or modifications due to changes in technical specifications.
© 2004 Eon Silicon Solution, Inc.,
Rev. I, Issue Date: 2011/10/26
www.eonssi.com