M29W641DH Datasheet, PDF (13/42 Pages) STMicroelectronics – 64 Mbit 4Mb x16, Uniform Block 3V Supply Flash Memory

M29W641DH, M29W641DL, M29W641DU
the lowest address block. The 50µs timer restarts
when an additional block is selected. The Status
Register can be read after the sixth Bus Write op-
eration. See the Status Register section for details
on how to identify if the Program/Erase Controller
has started the Block Erase operation.
If any selected blocks are protected then these are
ignored and all the other selected blocks are
erased. If all of the selected blocks are protected
the Block Erase operation appears to start but will
terminate within about 100µs, leaving the data un-
changed. No error condition is given when protect-
ed blocks are ignored.
During the Block Erase operation the memory will
ignore all commands except the Erase Suspend
command. Typical block erase times are given in
Table 4. All Bus Read operations during the Block
Erase operation will output the Status Register on
the Data Inputs/Outputs. See the section on the
Status Register for more details.
After the Block Erase operation has completed the
memory will return to the Read Mode, unless an
error has occurred. When an error occurs the
memory will continue to output the Status Regis-
ter. A Read/Reset command must be issued to re-
set the error condition and return to Read mode.
The Block Erase Command sets all of the bits in
the unprotected selected blocks to ’1’. All previous
data in the selected blocks is lost.
Erase Suspend Command
The Erase Suspend Command may be used to
temporarily suspend a Block Erase operation and
return the memory to Read mode. The command
requires one Bus Write operation.
The Program/Erase Controller will suspend within
the Erase Suspend Latency time of the Erase Sus-
pend Command being issued. Once the Program/
Erase Controller has stopped the memory will be
set to Read mode and the Erase will be suspend-
ed. If the Erase Suspend command is issued dur-
ing the period when the memory is waiting for an
additional block (before the Program/Erase Con-
troller starts) then the Erase is suspended immedi-
ately and will start immediately when the Erase
Resume Command is issued. It is not possible to
select any further blocks to erase after the Erase
Resume.
During Erase Suspend it is possible to Read and
Program cells in blocks that are not being erased;
both Read and Program operations behave as
normal on these blocks. If any attempt is made to
program in a protected block or in the suspended
block then the Program command is ignored and
the data remains unchanged. The Status Register
is not read and no error condition is given. Read-
ing from blocks that are being erased will output
the Status Register.
It is also possible to issue the Auto Select, Read
CFI Query and Unlock Bypass commands during
an Erase Suspend. The Read/Reset command
must be issued to return the device to Read Array
mode before the Resume command will be ac-
cepted.
Erase Resume Command
The Erase Resume command must be used to re-
start the Program/Erase Controller after an Erase
Suspend. The device must be in Read Array mode
before the Resume command will be accepted. An
erase can be suspended and resumed more than
once.
Enter Extended Block Command
The device has an extra 32 KWord block (Extend-
ed Block) that can only be accessed using the En-
ter Extended Block command. Three Bus write
cycles are required to issue the Extended Block
command. Once the command has been issued
the device enters Extended Block mode where all
Bus Read or Write operations to the Boot Block
addresses access the Extended Block. The Ex-
tended Block (with the same address as the Boot
Blocks) cannot be erased, and can be treated as
one-time programmable (OTP) memory. In Ex-
tended Block mode the Boot Blocks are not acces-
sible.
To exit from the Extended Block mode the Exit Ex-
tended Block command must be issued.
The Extended Block can be protected, however
once protected the protection cannot be undone.
Exit Extended Block Command
The Exit Extended Block command is used to exit
from the Extended Block mode and return the de-
vice to Read mode. Four Bus Write operations are
required to issue the command.
Block Protect and Chip Unprotect Commands
Groups of blocks can be protected against acci-
dental Program or Erase. The whole chip can be
unprotected to allow the data inside the blocks to
be changed.
Block Protect and Chip Unprotect operations are
described in Appendix D.
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