M29F400BT, M29F400BB
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.
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
15µs of the Erase Suspend Command being is-
sued. Once the Program/Erase Controller has
stopped the memory will be set to Read mode and
the Erase will be suspended. If the Erase Suspend
command is issued during the period when the
memory is waiting for an additional block (before
the Program/Erase Controller starts) then the
Erase is suspended immediately and will start im-
mediately when the Erase Resume Command is
issued. It will not be possible to select any further
blocks for erasure 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. Reading from blocks that
are being erased will output the Status Register. It
is also possible to enter the Auto Select mode: the
memory will behave as in the Auto Select mode on
all blocks until a Read/Reset command returns the
memory to Erase Suspend mode.
Erase Resume Command. The Erase Resume
command must be used to restart the Program/
Erase Controller from Erase Suspend. An erase
can be suspended and resumed more than once.
Table 9. Program, Erase Times and Program, Erase Endurance Cycles
(T = 0 to 70°C, –40 to 85°C or –40 to 125°C)
A
Typical after
(1)
Parameter
Min
Max
Unit
Typ
(1)
100k W/E Cycles
Chip Erase (All bits in the memory set to ‘0’)
Chip Erase
1.5
1.5
5
sec
sec
5
20
4
Block Erase (64 Kbytes)
0.6
8
0.6
8
sec
Program (Byte or Word)
150
18
9
µs
Chip Program (Byte by Byte)
Chip Program (Word by Word)
4.5
2.3
4.5
2.3
sec
sec
Program/Erase Cycles (per Block)
100,000
cycles
Note: 1. T = 25°C, V = 5V.
A
CC
9/22
STMICROELECTRONICS [ ST ]
