M29W200BT, M29W200BB
Unlock Bypass Command.
The Unlock Bypass
command is used in conjunction with the Unlock
Bypass Program command to program the memo-
ry. When the access time to the device is long (as
with some EPROM programmers) considerable
time saving can be made by using these com-
mands. Three Bus Write operations are required
to issue the Unlock Bypass command.
Once the Unlock Bypass command has been is-
sued the memory will only accept the Unlock By-
pass Program command and the Unlock Bypass
Reset command. The memory can be read as if in
Read mode.
Unlock Bypass Program Command.
The Un-
lock Bypass Program command can be used to
program one address in memory at a time. The
command requires two Bus Write operations, the
final write operation latches the address and data
in the internal state machine and starts the Pro-
gram/Erase Controller.
The Program operation using the Unlock Bypass
Program command behaves identically to the Pro-
gram operation using the Program command. A
protected block cannot be programmed; the oper-
ation cannot be aborted and the Status Register is
read. Errors must be reset using the Read/Reset
command, which leaves the device in Unlock By-
pass Mode. See the Program command for details
on the behavior.
Unlock Bypass Reset Command.
The Unlock
Bypass Reset command can be used to return to
Read/Reset mode from Unlock Bypass Mode.
Two Bus Write operations are required to issue the
Unlock Bypass Reset command.
Chip Erase Command.
The Chip Erase com-
mand can be used to erase the entire chip. Six Bus
Write operations are required to issue the Chip
Erase Command and start the Program/Erase
Controller.
If any blocks are protected then these are ignored
and all the other blocks are erased. If all of the
blocks are protected the Chip Erase operation ap-
pears to start but will terminate within about 100µs,
leaving the data unchanged. No error condition is
given when protected blocks are ignored.
During the erase operation the memory will ignore
all commands. It is not possible to issue any com-
mand to abort the operation. Typical chip erase
times are given in Table 9. All Bus Read opera-
tions during the Chip Erase operation will output
the Status Register on the Data Inputs/Outputs.
See the section on the Status Register for more
details.
After the Chip 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 Chip Erase Command sets all of the bits in un-
protected blocks of the memory to ’1’. All previous
data is lost.
Block Erase Command.
The Block Erase com-
mand can be used to erase a list of one or more
blocks. Six Bus Write operations are required to
select the first block in the list. Each additional
block in the list can be selected by repeating the
sixth Bus Write operation using the address of the
additional block. The Block Erase operation starts
the Program/Erase Controller about 50µs after the
last Bus Write operation. Once the Program/Erase
Controller starts it is not possible to select any
more blocks. Each additional block must therefore
be selected within 50µs of the last block. The 50µs
timer restarts when an additional block is selected.
The Status Register can be read after the sixth
Bus Write operation. See the Status Register 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
and Read/Reset commands. Typical block erase
times are given in Table 9. All Bus Read opera-
tions 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.
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STMICROELECTRONICS [ STMICROELECTRONICS ]
