Am29DL16xC
27
P R E L I M I NARY
RY/BY#: Ready/Busy#
The RY/BY# is a dedicated, open-drain output pin
which indicates whether an Embedded Algorithm is in
progress or complete. The RY/BY# status is valid after
the rising edge of the final WE# pulse in the command
sequence. Since RY/BY# is an open-drain output, sev-
eral RY/BY# pins can be tied together in parallel with a
pull-up resistor to V
CC.
If the output is low (Busy), the device is actively eras-
ing or programming. (This includes programming in
the Erase Suspend mode.) If the output is high
(Ready), the device is reading array data, the standby
mode, or o ne of the ban ks is in the e rase-sus-
pend-read mode.
DQ6: Toggle Bit I
Toggle Bit I on DQ6 indicates whether an Embedded
Program or Erase algorithm is in progress or com-
plete, or whether the device has entered the Erase
Suspend mode. Toggle Bit I may be read at any ad-
dress, 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 op-
eration, successive read cycles to any address cause
DQ6 to toggle. The system may use either OE# or
CE# to control the read cycles. When the operation is
complete, DQ6 stops toggling.
After an erase command sequence is written, if all
sectors selected for erasing are protected, DQ6 tog-
gles for approximately 100 s, 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
protected.
The system can use DQ6 and DQ2 together to deter-
min e whethe r a sector is actively e rasin g 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 Sus-
pend mode, DQ6 stops toggling. However, the system
must also use DQ2 to determine which sectors are
erasing or erase-suspended. Alternatively, the system
If a program address falls within a protected sector,
DQ6 toggles for approximately 1
s 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 Embedded Pro-
gram algorithm is complete.
Table 15 shows the outputs for Toggle Bit I on DQ6.
timing diagrams.
Figure 23 shows the differences be-
tween DQ2 and DQ6 in graphical form. See also the
START
No
Yes
DQ5 = 1?
No
Yes
Toggle Bit
= Toggle?
No
Program/Erase
Operation Not
Complete, Write
Reset Command
Program/Erase
Operation Complete
Read DQ7–DQ0
Toggle Bit
= Toggle?
Read DQ7–DQ0
Twice
Read DQ7–DQ0
21533C-11
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.
Figure 6.
Toggle Bit Algorithm