AM29DL640D120 AMD [Advanced Micro Devices], AM29DL640D120 Datasheet - Page 27

• Manufacturer Part Number: AM29DL640D120
• Description: 64 Megabit CMOS 3.0 Volt-only, Simultaneous Read/Write Flash Memory
• Manufacturer: AMD [Advanced Micro Devices]

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 de-
termine the status of the erase operation by reading
DQ7, DQ6, DQ2, or RY/BY# in the erasing bank. Refer
to the Write Operation Status section for information
on these status bits.
Once the sector erase operation has begun, only the
Erase Suspend command is valid. All other com-
mands are ignored. However, note that a hardware
reset immediately 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.
Figure 5 illustrates the algorithm for the erase opera-
tion. Refer to the Erase and Program Operations
tables in the AC Characteristics section for parame-
ters, and Figure 20 section for timing diagrams.
Erase Suspend/Erase Resume
Commands
The Erase Suspend command, B0h, allows the sys-
tem 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 command is valid only during the
sector erase operation, including the 80 µs time-out
period during the sector erase command sequence.
The Erase Suspend command is ignored if written dur-
ing the chip erase operation or Embedded Program
algorithm.
When the Erase Suspend command is written during
the sector erase operation, the device requires a max-
imum of 20 µs to suspend the erase operation.
However, when the Erase Suspend command is writ-
ten during the sector erase time-out, the device
immediately terminates the time-out period and sus-
p e n d s t h e e r a s e o p e r a t i o n . A d d r e s s e s a r e
“don’t-ca res” when w r iting the Eras e s uspe nd
command.
After the erase operation has been suspended, the
bank enters the erase-suspend-read mode. The sys-
tem can read data from or program data to any sector
not selected for erasure. (The device “erase sus-
pends” all sectors selected for erasure.) Reading at
any address within erase-suspended sectors pro-
duces status 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 infor-
mation on these status bits.
After an erase-suspended program operation is com-
plete, the bank returns to the erase-suspend-read
26
Am29DL640D
mode. The system can determine the status of the
program operation using the DQ7 or DQ6 status bits,
just as in the standard Byte Program operation.
Refer to the Write Operation Status section for more
information.
In the erase-suspend-read mode, the system can also
issue the autoselect command sequence. The device
allows reading autoselect codes even at addresses
within erasing sectors, since the codes are not stored
in the memory array. When the device exits the au-
toselect mode, the device rever ts to the Erase
Suspend mode, and is ready for another valid opera-
tion. Refer to the Autoselect Mode and Autoselect
Command Sequence sections for details.
To resume the sector erase operation, the system
must write the Erase Resume command (address bits
are don’t care). The bank address of the erase-sus-
pended bank is required when writing this command.
Further writes of the Resume command are ignored.
Another Erase Suspend command can be written after
the chip has resumed erasing.
Notes:
1. See Table 12 for erase command sequence.
2. See the section on DQ3 for information on the sector
erase timer.
No
Figure 5. Erase Operation
Command Sequence
Data Poll to Erasing
Erasure Completed
Bank from System
Write Erase
Data = FFh?
(Notes 1, 2)
START
Yes
Embedded
Erase
algorithm
in progress
October 7, 2004