AM29BDS640G Datasheet, PDF (37/78 Pages) SPANSION – 64 Megabit (4 M x 16-Bit) CMOS 1.8 Volt-only Simultaneous Read/Write, Burst Mode Flash Memory

Preliminary
The system can monitor DQ3 to determine if the sector erase timer has timed out
(See “DQ3: Sector Erase Timer” section on page 43.). The time-out begins from
the rising edge of the final WE# pulse in the command sequence.
When the Embedded Erase algorithm is complete, the bank returns to reading
array data and addresses are no longer latched. Note that while the Embedded
Erase operation is in progress, the system can read data from the non-erasing
bank. The system can determine the status of the erase operation by reading
DQ7 or DQ6/DQ2 in the erasing bank. Refer to the “Write Operation Status” sec-
tion on page 38 section for information on these status bits.
Once the sector erase operation has begun, only the Erase Suspend command is
valid. All other commands are ignored. However, note that a hardware reset im-
mediately terminates the erase operation. If that occurs, the sector erase
command sequence should be reinitiated once that bank has returned to reading
array data, to ensure data integrity.
The host system may also initiate the sector erase command sequence while the
device is in the unlock bypass mode. The command sequence is four cycles cycles
in length instead of six cycles.
Figure 2 illustrates the algorithm for the erase operation. Refer to the Erase/Pro-
gram Operations table in the AC Characteristics section for parameters and timing
diagrams.
Erase Suspend/Erase Resume Commands
The Erase Suspend command, B0h, allows the system to interrupt a sector erase
operation and then read data from, or program data to, any sector not selected
for erasure. The bank address is required when writing this command. This com-
mand is valid only during the sector erase operation, including the minimum 50
µs time-out period during the sector erase command sequence. The Erase Sus-
pend command is ignored if written during the chip erase operation or Embedded
Program algorithm.
When the Erase Suspend command is written during the sector erase operation,
the device requires a maximum of 35 µs to suspend the erase operation. How-
ever, when the Erase Suspend command is written during the sector erase time-
out, the device immediately terminates the time-out period and suspends the
erase operation.
After the erase operation has been suspended, the bank enters the erase-sus-
pend-read mode. The system can read data from or program data to any sector
not selected for erasure. (The device “erase suspends” all sectors selected for
erasure.) Reading at any address within erase-suspended sectors produces sta-
tus information on DQ7–DQ0. The system can use DQ7, or DQ6 and DQ2
together, to determine if a sector is actively erasing or is erase-suspended. Refer
to the Write Operation Status section for information on these status bits.
After an erase-suspended program operation is complete, the bank returns to the
erase-suspend-read mode. The system can determine the status of the program
operation using the DQ7 or DQ6 status bits, just as in the standard program op-
eration. Refer to the “Write Operation Status” section for more information.
In the erase-suspend-read mode, the system can also issue the autoselect com-
mand sequence. Refer to the “Autoselect Functions” section on page 16 and
“Autoselect Command Sequence” section on page 31 sections for details.
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