AM29BDS640G SPANSION [SPANSION], AM29BDS640G Datasheet - Page 43

• Manufacturer Part Number: AM29BDS640G
• Description: 64 Megabit (4 M x 16-Bit) CMOS 1.8 Volt-only Simultaneous Read/Write, Burst Mode Flash Memory
• Manufacturer: SPANSION [SPANSION]

October 1, 2003 25903C1
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.
The “Toggle Bit II” 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. But DQ2 cannot distinguish whether the sector is ac-
tively erasing or is erase-suspended. DQ6, by comparison, indicates whether the
device is actively erasing, or is in Erase Suspend, but cannot distinguish which
No
P r e l i m i n a r y
Figure 5. Toggle Bit Algorithm
Complete, Write
Reset Command
Read DQ7–DQ0
Read DQ7–DQ0
Read DQ7–DQ0
Program/Erase
Operation Not
Toggle Bit
DQ5 = 1?
Toggle Bit
= Toggle?
= Toggle?
START
Twice
Am29BDS640G
Yes
Yes
Yes
Operation Complete
No
No
Program/Erase
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