D A T A S H E E T
See the following for additional information: Figure 4
RDY: Ready
(toggle bit flowchart), DQ6: Toggle Bit I (description),
Figure 17 (toggle bit timing diagram), and Table 11
(compares DQ2 and DQ6).
The RDY is a dedicated output that indicates (when at
logic low) the system should wait until RDY returns high
before expecting the next word of data.
RDY functions only while reading data in burst mode.
The following conditions cause the RDY output to be
low: during the initial access (in burst mode); after the
boundary that occurs every 64 words beginning with
the 63rd address, 3Eh; and when the clock frequency
is less than 6 MHz (in which case RDY is low every third
clock). The RDY pin will also switch during status reads
if there is a clock signal at the CLK input. If RDY goes
low, it indicates that the status data is not yet valid and
that the system should wait until RDY returns high.
START
Read Byte
(DQ0-DQ7)
Address = VA
Read Byte
(DQ0-DQ7)
Address = VA
DQ6: Toggle Bit I
Toggle Bit I on DQ6 indicates whether an Embedded
Program or Erase algorithm is in progress or complete,
or whether the device has entered the Erase Suspend
mode. Toggle Bit I may 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.
No
DQ6 = Toggle?
Yes
No
DQ5 = 1?
During an Embedded Program or Erase algorithm
operation, successive read cycles to any address
cause DQ6 to toggle. Note that OE# must be low during
toggle bit status reads. When the operation is com-
plete, DQ6 stops toggling.
Yes
Read Byte Twice
(DQ 0-DQ7)
Adrdess = VA
After an erase command sequence is written, if all
sectors selected for erasing are protected, DQ6 toggles
for approximately 100 µs, then returns to reading array
data. If not all selected sectors are protected, the
Embedded Erase algorithm erases the unprotected
sectors, and ignores the selected sectors that are pro-
tected.
No
DQ6 = Toggle?
The system can use DQ6 and DQ2 together to deter-
mine 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 toggling. However, the
system must also use DQ2 to determine which sectors
are erasing or erase-suspended. Alternatively, the
system can use DQ7 (see the subsection on DQ7:
Data# Polling).
Yes
FAIL
PASS
Note: The system should recheck the toggle bit even if DQ5
= “1” because the toggle bit may stop toggling as DQ5
changes to “1.” See the subsections on DQ6 and DQ2 for
more information.
If a program address falls within a protected sector,
DQ6 toggles for approximately 1 μs after the program
command sequence is written, then returns to reading
array data.
Figure 4. Toggle Bit Algorithm
DQ6 also toggles during the erase-suspend-program
mode, and stops toggling once the Embedded
Program algorithm is complete.
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