28 Am49DL640BG March 8, 2002
PRELIMINARY
DQ7, DQ6, DQ 2, or RY/BY# in the erasing bank.
Refer to the Flash Write Operation Status section for
informa tio n on these status bits.
Once the sector erase opera tion has begu n, only the
Erase Suspend command is valid. All other com-
mands are ignored. However, note t hat a hardware
reset immediatel y 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 dat a integrity.
Figu re 4 i llustra tes the al gorithm fo r the e rase oper a-
tion. Refer to the Erase and Program O perations ta-
bles in the AC Charact eristics section for parameters,
and Figure 20 section for timing diagrams.
Erase Suspend/Erase Resume
Commands
The Erase Suspend command, B0h, allows the sys-
tem to int errupt a sector erase operat ion and then read
data from, or program data to, any sector not selected
for er asur e. The bank addr es s is required when wri ting
this comman d. This c ommand is v alid only d uring 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.
Whe n the E ras e S uspen d co mmand is w ritte n dur ing
the sector erase operation, the device requires a max -
imum of 20 µs to suspend the erase operation. How-
ever, when the Erase Suspe nd command is written
during the sector erase time-out, the device immedi-
ately terminates the time-out period and suspends the
erase operati on. Addresse s are “don’t-cares” when
writing the Era se suspend command.
After th e erase operation has bee n suspended , the
bank e nter s the er ase-suspen d-read m ode. Th e 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 Flash Write Operation Status section for
informa tio n on these status bits.
After an eras e-suspe nde d prog ram operatio n is c om-
plete, the bank returns to the erase-suspend-read
mode. The system can determine the status of the
progr am ope ration u sing the DQ7 or DQ6 status bits,
just as in the standard Byte Program operation.
Ref er to the F las h Writ e Op erat ion Stat us s ectio n fo r
more information.
In the erase-suspend-read mode, the system can also
issu e the autoselec t comm and seque nce. The device
allows reading autoselect codes even at addresses
within erasing sectors, since the code s are not stored
in the mem ory array. When the device exits the au-
toselect mode, the device reverts to the Erase Sus-
pen d mode, and is rea dy for ano ther vali d operati on.
Refer to the S ector/Sector Block Protection and Un-
protection and Autoselect Comm and Sequence sec-
tions for d e ta ils.
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-
pend ed bank is req uired wh en wr iting t his comma nd.
Further writes of the Resume command are ignored.
Another Erase Suspend com mand can be written aft er
the chip has resumed erasing.
Figure 4. Erase Operation
START
Write Erase
Command Sequence
(Notes 1, 2)
Data Poll to Erasing
Bank from System
Data = FFh?
No
Yes
Erasure Completed
Embedded
Erase
algorithm
in progress
Notes:
1. See Table 12 for erase command sequence.
2. See the section on DQ3 for information on the sector
erase timer.