AM29LV642D AMD [Advanced Micro Devices], AM29LV642D Datasheet - Page 34

• Manufacturer Part Number: AM29LV642D
• Manufacturer: AMD [Advanced Micro Devices]

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
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 in the read mode, the standby
mode, or the device is in the erase-suspend-read
mode.
Table 11 shows the outputs for RY/BY#.
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# (or CE2#) 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 toggles for approxi-
mately 100 µs, then returns to reading array data. If not all
selected sectors are protected, the Embedded Erase algo-
rithm erases the unprotected sectors, and ignores the se-
lected 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 de-
vice enters the Erase Suspend mode, DQ6 stops toggling.
However, the system must also use DQ2 to determine
which sectors are erasing or erase-suspended. Alterna-
tively, the system can use DQ7 (see the subsection on
DQ7: Data# Polling).
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.
DQ6 also toggles during the erase-suspend-program
mode, and stops toggling once the Embedded Pro-
gram algorithm is complete.
32
CC
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D A T A
Am29LV642D
S H E E T
Table 11 shows the outputs for Toggle Bit I on DQ6.
Figure 6 shows the toggle bit algorithm. Figure 19 in
the “AC Characteristics” section shows the toggle bit
timing diagrams. Figure 20 shows the differences be-
tween DQ2 and DQ6 in graphical form. See also the
subsection on DQ2: Toggle Bit II.
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.
No
Figure 6. Toggle Bit Algorithm
Complete, Write
Reset Command
Read DQ7–DQ0
Read DQ7–DQ0
Read DQ7–DQ0
Program/Erase
Operation Not
Toggle Bit
Toggle Bit
DQ5 = 1?
= Toggle?
= Toggle?
START
Twice
Yes
Yes
Yes
Operation Complete
No
No
Program/Erase
25022A2 May 5, 2006