M29F400BB-70N1 ,4 MBIT (512KB X8 OR 256KB X16, BOOT BLOCK) SINGLE SUPPLY FLASH MEMORYLogic Diagram■ ERASE SUSPEND and RESUME MODES– Read and Program another Block duringErase Suspend■ ..
M29F400BB-70N1 ,4 MBIT (512KB X8 OR 256KB X16, BOOT BLOCK) SINGLE SUPPLY FLASH MEMORYM29F400BTM29F400BB4 Mbit (512Kb x8 or 256Kb x16, Boot Block)Single Supply Flash Memory■ SINGLE 5V±1 ..
M29F400BB70N1E , 4 Mbit (512Kb x8 or 256Kb x16, Boot Block) single supply Flash memory
M29F400BB-70N1E , 4 Mbit (512Kb x8 or 256Kb x16, Boot Block) single supply Flash memory
M29F400BB70N1T ,4 MBIT (512KB X8 OR 256KB X16, BOOT BLOCK) SINGLE SUPPLY FLASH MEMORYAbsolute Maximum Ratings" maycause permanent damage to the device. These are stress ratings only an ..
M29F400BB-70N1T ,4 MBIT (512KB X8 OR 256KB X16, BOOT BLOCK) SINGLE SUPPLY FLASH MEMORYAbsolute Maximum Ratings Symbol Parameter Value UnitAmbient Operating Temperature (Temperature Rang ..
M50734SP-10 , 8-BIT CMOS MICROCOMPUTER
M50734SP-10 , 8-BIT CMOS MICROCOMPUTER
M50747-161SP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M50747-2B4SP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M50747-2B4SP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M50940-303SP , SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
M29F400BB 70N6-M29F400BB45N1-M29F400BB-45N1-M29F400BB55M1-M29F400BB-55M1-M29F400BB70M1-M29F400BB-70M1-M29F400BB70N1-M29F400BB-70N1-M29F400BB70N1T-M29F400BB-70N1T-M29F400BB70N6-M29F400BB-70N6-M29F400BT-M29F400BT55M1-M29F400BT-55M1-M29F400BT55N1-M29F400BT-55N1-M29F400BT70M
4 MBIT (512KB X8 OR 256KB X16, BOOT BLOCK) SINGLE SUPPLY FLASH MEMORY
1/22July 2000
M29F400BT
M29F400BB4 Mbit (512Kb x8 or 256Kb x16, Boot Block)
Single Supply Flash Memory SINGLE 5V±10% SUPPLY VOLTAGE for
PROGRAM, ERASE and READ OPERATIONS ACCESS TIME: 45ns PROGRAMMING TIME 8μs per Byte/Word typical 11 MEMORY BLOCKS 1 Boot Block (Top or Bottom Location) 2 Parameter and 8 Main Blocks PROGRAM/ERASE CONTROLLER Embedded Byte/Word Program algorithm Embedded Multi-Block/Chip Erase algorithm Status Register Polling and Toggle Bits Ready/Busy Output Pin ERASE SUSPEND and RESUME MODES Read and Program another Block during
Erase Suspend UNLOCK BYPASS PROGRAM COMMAND Faster Production/Batch Programming TEMPORARY BLOCK UNPROTECTION
MODE LOW POWER CONSUMPTION Standby and Automatic Standby 100,000 PROGRAM/ERASE CYCLES per
BLOCK 20 YEARS DATA RETENTION Defectivity below 1 ppm/year ELECTRONIC SIGNATURE Manufacturer Code: 0020h Top Device Code M29F400BT: 00D5h Bottom Device Code M29F400BB: 00D6h
M29F400BT, M29F400BB
Table 1. Signal Names
SUMMARY DESCRIPTIONThe M29F400B is a 4 Mbit (512Kb x8 or 256Kb
x16) non-volatile memory that can be read, erased
and reprogrammed. These operations can be per-
formed using a single 5V supply. On power-up the
memory defaults to its Read mode where it can be
read in the same way as a ROM or EPROM. The
M29F400B is fully backward compatible with the
M29F400.
The memory is divided into blocks that can be
erased independently so it is possible to preserve
valid data while old data is erased. Each block can
be protected independently to prevent accidental
Program or Erase commands from modifying the
memory. Program and Erase commands are writ-
ten to the Command Interface of the memory. An
on-chip Program/Erase Controller simplifies the
process of programming or erasing the memory by
taking care of all of the special operations that are
required to update the memory contents. The end
of a program or erase operation can be detected
and any error conditions identified. The command
set required to control the memory is consistent
with JEDEC standards.
3/22
M29F400BT, M29F400BBThe blocks in the memory are asymmetrically ar-
ranged, see Tables 3 and 4, Block Addresses. The
first or last 64 Kbytes have been divided into four
additional blocks. The 16 Kbyte Boot Block can be
used for small initialization code to start the micro-
processor, the two 8 Kbyte Parameter Blocks can
be used for parameter storage and the remaining
32K is a small Main Block where the application
may be stored.
Chip Enable, Output Enable and Write Enable sig-
nals control the bus operation of the memory.
They allow simple connection to most micropro-
cessors, often without additional logic.
The memory is offered in TSOP48 (12 x 20mm)
and SO44 packages and it is supplied with all the
bits erased (set to ’1’).
Table 2. Absolute Maximum Ratings (1)Note:1. Except for the rating "Operating Temperature Range", stresses above those listed in the Table "Absolute Maximum Ratings" may
cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions
above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating condi-
tions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant qual-
ity documents. Minimum Voltage may undershoot to –2V during transition and for less than 20ns during transitions.
Table 3. Top Boot Block Addresses,
M29F400BT
Table 4. Bottom Boot Block addresses,
M29F400BB
M29F400BT, M29F400BB
SIGNAL DESCRIPTIONSSee Figure 1, Logic Diagram, and Table 1, Signal
Names, for a brief overview of the signals connect-
ed to this device.
Address Inputs (A0-A17). The Address Inputs
select the cells in the memory array to access dur-
ing Bus Read operations. During Bus Write opera-
tions they control the commands sent to the
Command Interface of the internal state machine.
Data Inputs/Outputs (DQ0-DQ7). The Data In-
puts/Outputs output the data stored at the selected
address during a Bus Read operation. During Bus
Write operations they represent the commands
sent to the Command Interface of the internal state
machine.
Data Inputs/Outputs (DQ8-DQ14). The Data In-
puts/Outputs output the data stored at the selected
address during a Bus Read operation when BYTE
is High, VIH. When BYTE is Low, VIL, these pins
are not used and are high impedance. During Bus
Write operations the Command Register does not
use these bits. When reading the Status Register
these bits should be ignored.
Data Input/Output or Address Input (DQ15A-1).When BYTE is High, VIH, this pin behaves as a
Data Input/Output pin (as DQ8-DQ14). When
BYTE is Low, VIL, this pin behaves as an address
pin; DQ15A–1 Low will select the LSB of the Word
on the other addresses, DQ15A–1 High will select
the MSB. Throughout the text consider references
to the Data Input/Output to include this pin when
BYTE is High and references to the Address In-
puts to include this pin when BYTE is Low except
when stated explicitly otherwise.
Chip Enable (E). The Chip Enable, E, activates
the memory, allowing Bus Read and Bus Write op-
erations to be performed. When Chip Enable is
High, VIH, all other pins are ignored.
Output Enable (G). The Output Enable, G, con-
trols the Bus Read operation of the memory.
Write Enable (W). The Write Enable, W, controls
the Bus Write operation of the memory’s Com-
mand Interface.
Reset/Block Temporary Unprotect (RP). The Re-
set/Block Temporary Unprotect pin can be used to
apply a Hardware Reset to the memory or to tem-
porarily unprotect all Blocks that have been pro-
tected.
A Hardware Reset is achieved by holding Reset/
Block Temporary Unprotect Low, VIL, for at least
tPLPX. After Reset/Block Temporary Unprotect
goes High, VIH, the memory will be ready for Bus
Read and Bus Write operations after tPHEL or
tRHEL, whichever occurs last. See the Ready/Busy
Output section, Table 17 and Figure 11, Reset/
Temporary Unprotect AC Characteristics for more
details.
Holding RP at VID will temporarily unprotect the
protected Blocks in the memory. Program and
Erase operations on all blocks will be possible.
The transition from VIH to VID must be slower than
tPHPHH.
Ready/Busy Output (RB). The Ready/Busy pin
is an open-drain output that can be used to identify
when the memory array can be read. Ready/Busy
is high-impedance during Read mode, Auto Select
mode and Erase Suspend mode.
After a Hardware Reset, Bus Read and Bus Write
operations cannot begin until Ready/Busy be-
comes high-impedance. See Table 17 and Figure
11, Reset/Temporary Unprotect AC Characteris-
tics.
During Program or Erase operations Ready/Busy
is Low, VOL. Ready/Busy will remain Low during
Read/Reset commands or Hardware Resets until
the memory is ready to enter Read mode.
The use of an open-drain output allows the Ready/
Busy pins from several memories to be connected
to a single pull-up resistor. A Low will then indicate
that one, or more, of the memories is busy.
Byte/Word Organization Select (BYTE). The Byte/
Word Organization Select pin is used to switch be-
tween the 8-bit and 16-bit Bus modes of the mem-
ory. When Byte/Word Organization Select is Low,
VIL, the memory is in 8-bit mode, when it is High,
VIH, the memory is in 16-bit mode.
VCC Supply Voltage. The VCC Supply Voltage
supplies the power for all operations (Read, Pro-
gram, Erase etc.).
The Command Interface is disabled when the VCC
Supply Voltage is less than the Lockout Voltage,
VLKO. This prevents Bus Write operations from ac-
cidentally damaging the data during power up,
power down and power surges. If the Program/
Erase Controller is programming or erasing during
this time then the operation aborts and the memo-
ry contents being altered will be invalid.
A 0.1μF capacitor should be connected between
the VCC Supply Voltage pin and the VSS Ground
pin to decouple the current surges from the power
supply. The PCB track widths must be sufficient to
carry the currents required during program and
erase operations, ICC4.
Vss Ground. The VSS Ground is the reference
for all voltage measurements.
5/22
M29F400BT, M29F400BB
Table 5. Bus Operations, BYTE = VILNote: X = VIL or VIH.
Table 6. Bus Operations, BYTE = VIHNote: X = VIL or VIH.
BUS OPERATIONSThere are five standard bus operations that control
the device. These are Bus Read, Bus Write, Out-
put Disable, Standby and Automatic Standby. See
Tables 5 and 6, Bus Operations, for a summary.
Typically glitches of less than 5ns on Chip Enable
or Write Enable are ignored by the memory and do
not affect bus operations.
Bus Read. Bus Read operations read from the
memory cells, or specific registers in the Com-
mand Interface. A valid Bus Read operation in-
volves setting the desired address on the Address
Inputs, applying a Low signal, VIL, to Chip Enable
and Output Enable and keeping Write Enable
High, VIH. The Data Inputs/Outputs will output the
value, see Figure 8, Read Mode AC Waveforms,
and Table 14, Read AC Characteristics, for details
of when the output becomes valid.
Bus Write. Bus Write operations write to the
Command Interface. A valid Bus Write operation
begins by setting the desired address on the Ad-
dress Inputs. The Address Inputs are latched by
the Command Interface on the falling edge of Chip
Enable or Write Enable, whichever occurs last.
The Data Inputs/Outputs are latched by the Com-
mand Interface on the rising edge of Chip Enable
or Write Enable, whichever occurs first. Output En-
able must remain High, VIH, during the whole Bus
Write operation. See Figures 9 and 10, Write AC
Waveforms, and Tables 15 and 16, Write AC
Characteristics, for details of the timing require-
ments.
Output Disable. The Data Inputs/Outputs are in
the high impedance state when Output Enable is
High, VIH.
Standby. When Chip Enable is High, VIH, the
Data Inputs/Outputs pins are placed in the high-
impedance state and the Supply Current is re-
duced to the Standby level.
When Chip Enable is at VIH the Supply Current is
reduced to the TTL Standby Supply Current, ICC2.
To further reduce the Supply Current to the CMOS
Standby Supply Current, ICC3, Chip Enable should
be held within VCC ± 0.2V. For Standby current
levels see Table 13, DC Characteristics.
During program or erase operations the memory
will continue to use the Program/Erase Supply
Current, ICC4, for Program or Erase operations un-
til the operation completes.
M29F400BT, M29F400BB
Automatic Standby. If CMOS levels (VCC ± 0.2V)
are used to drive the bus and the bus is inactive for
150ns or more the memory enters Automatic
Standby where the internal Supply Current is re-
duced to the CMOS Standby Supply Current, ICC3.
The Data Inputs/Outputs will still output data if a
Bus Read operation is in progress.
Special Bus OperationsAdditional bus operations can be performed to
read the Electronic Signature and also to apply
and remove Block Protection. These bus opera-
tions are intended for use by programming equip-
ment and are not usually used in applications.
They require VID to be applied to some pins.
Electronic Signature. The memory has two
codes, the manufacturer code and the device
code, that can be read to identify the memory.
These codes can be read by applying the signals
listed in Tables 5 and 6, Bus Operations.
Block Protection and Blocks Unprotection. Each
block can be separately protected against acci-
dental Program or Erase. Protected blocks can be
unprotected to allow data to be changed.
There are two methods available for protecting
and unprotecting the blocks, one for use on pro-
gramming equipment and the other for in-system
use. For further information refer to Application
Note AN1122, Applying Protection and Unprotec-
tion to M29 Series Flash.
COMMAND INTERFACEAll Bus Write operations to the memory are inter-
preted by the Command Interface. Commands
consist of one or more sequential Bus Write oper-
ations. Failure to observe a valid sequence of Bus
Write operations will result in the memory return-
ing to Read mode. The long command sequences
are imposed to maximize data security.
The address used for the commands changes de-
pending on whether the memory is in 16-bit or 8-
bit mode. See either Table 7, or 8, depending on
the configuration that is being used, for a summary
of the commands.
Read/Reset Command. The Read/Reset com-
mand returns the memory to its Read mode where
it behaves like a ROM or EPROM. It also resets
the errors in the Status Register. Either one or
three Bus Write operations can be used to issue
the Read/Reset command.
If the Read/Reset command is issued during a
Block Erase operation or following a Programming
or Erase error then the memory will take upto 10μs
to abort. During the abort period no valid data can
be read from the memory. Issuing a Read/Reset
command during a Block Erase operation will
leave invalid data in the memory.
Auto Select Command. The Auto Select com-
mand is used to read the Manufacturer Code, the
Device Code and the Block Protection Status.
Three consecutive Bus Write operations are re-
quired to issue the Auto Select command. Once
the Auto Select command is issued the memory
remains in Auto Select mode until another com-
mand is issued.
From the Auto Select mode the Manufacturer
Code can be read using a Bus Read operation
with A0 = VIL and A1 = VIL. The other address bits
may be set to either VIL or VIH. The Manufacturer
Code for STMicroelectronics is 0020h.
The Device Code can be read using a Bus Read
operation with A0 = VIH and A1 = VIL. The other
address bits may be set to either VIL or VIH. The
Device Code for the M29F400BT is 00D5h and for
the M29F400BB is 00D6h.
7/22
M29F400BT, M29F400BB
Table 7. Commands, 16-bit mode, BYTE = VIH
Table 8. Commands, 8-bit mode, BYTE = VILNote: X Don’t Care, PA Program Address, PD Program Data, BA Any address in the Block.
All values in the table are in hexadecimal.
The Command Interface only uses A–1, A0-A10 and DQ0-DQ7 to verify the commands; A11-A17, DQ8-DQ14 and DQ15 are Don’t Care.
DQ15A–1 is A–1 when BYTE is VIL or DQ15 when BYTE is VIH.
Read/Reset. After a Read/Reset command, read the memory as normal until another command is issued.
Auto Select. After an Auto Select command, read Manufacturer ID, Device ID or Block Protection Status.
Program, Unlock Bypass Program, Chip Erase, Block Erase. After these commands read the Status Register until the Program/EraseController completes and the memory returns to Read Mode. Add additional Blocks during Block Erase Command with additional Bus Write
Operations until Timeout Bit is set.
Unlock Bypass. After the Unlock Bypass command issue Unlock Bypass Program or Unlock Bypass Reset commands.
Unlock Bypass Reset. After the Unlock Bypass Reset command read the memory as normal until another command is issued.
Erase Suspend. After the Erase Suspend command read non-erasing memory blocks as normal, issue Auto Select and Program commandson non-erasing blocks as normal.
Erase Resume. After the Erase Resume command the suspended Erase operation resumes, read the Status Register until the Program/Erase Controller completes and the memory returns to Read Mode.
M29F400BT, M29F400BBThe Block Protection Status of each block can be
read using a Bus Read operation with A0 = VIL, = VIH, and A12-A17 specifying the address of
the block. The other address bits may be set to ei-
ther VIL or VIH. If the addressed block is protected
then 01h is output on Data Inputs/Outputs DQ0-
DQ7, otherwise 00h is output.
Program Command. The Program command
can be used to program a value to one address in
the memory array at a time. The command re-
quires four Bus Write operations, the final write op-
eration latches the address and data in the internal
state machine and starts the Program/Erase Con-
troller.
If the address falls in a protected block then the
Program command is ignored, the data remains
unchanged. The Status Register is never read and
no error condition is given.
During the program operation the memory will ig-
nore all commands. It is not possible to issue any
command to abort or pause the operation. Typical
program times are given in Table 9. Bus Read op-
erations during the program operation will output
the Status Register on the Data Inputs/Outputs.
See the section on the Status Register for more
details.
After the program 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.
Note that the Program command cannot change a
bit set at ’0’ back to ’1’. One of the Erase Com-
mands must be used to set all the bits in a block or
in the whole memory from ’0’ to ’1’.
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.
9/22
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(TA = 0 to 70°C, –40 to 85°C or –40 to 125°C)
Note:1. TA = 25°C, VCC = 5V.
M29F400BT, M29F400BB
STATUS REGISTERBus Read operations from any address always
read the Status Register during Program and
Erase operations. It is also read during Erase Sus-
pend when an address within a block being erased
is accessed.
The bits in the Status Register are summarized in
Table 10, Status Register Bits.
Data Polling Bit (DQ7). The Data Polling Bit can
be used to identify whether the Program/Erase
Controller has successfully completed its opera-
tion or if it has responded to an Erase Suspend.
The Data Polling Bit is output on DQ7 when the
Status Register is read.
During Program operations the Data Polling Bit
outputs the complement of the bit being pro-
grammed to DQ7. After successful completion of
the Program operation the memory returns to
Read mode and Bus Read operations from the ad-
dress just programmed output DQ7, not its com-
plement.
During Erase operations the Data Polling Bit out-
puts ’0’, the complement of the erased state of
DQ7. After successful completion of the Erase op-
eration the memory returns to Read Mode.
In Erase Suspend mode the Data Polling Bit will
output a ’1’ during a Bus Read operation within a
block being erased. The Data Polling Bit will
change from a ’0’ to a ’1’ when the Program/Erase
Controller has suspended the Erase operation.
Figure 4, Data Polling Flowchart, gives an exam-
ple of how to use the Data Polling Bit. A Valid Ad-
dress is the address being programmed or an
address within the block being erased.
Toggle Bit (DQ6). The Toggle Bit can be used to
identify whether the Program/Erase Controller has
successfully completed its operation or if it has re-
sponded to an Erase Suspend. The Toggle Bit is
output on DQ6 when the Status Register is read.
During Program and Erase operations the Toggle
Bit changes from ’0’ to ’1’ to ’0’, etc., with succes-
sive Bus Read operations at any address. After
successful completion of the operation the memo-
ry returns to Read mode.
During Erase Suspend mode the Toggle Bit will
output when addressing a cell within a block being
erased. The Toggle Bit will stop toggling when the
Program/Erase Controller has suspended the
Erase operation.
Figure 5, Data Toggle Flowchart, gives an exam-
ple of how to use the Data Toggle Bit.
Error Bit (DQ5). The Error Bit can be used to
identify errors detected by the Program/Erase
Controller. The Error Bit is set to ’1’ when a Pro-
gram, Block Erase or Chip Erase operation fails to
write the correct data to the memory. If the Error
Bit is set a Read/Reset command must be issued
before other commands are issued. The Error bit
is output on DQ5 when the Status Register is read.
Note that the Program command cannot change a
bit set at ’0’ back to ’1’ and attempting to do so may
or may not set DQ5 at ‘1’. In both cases, a succes-
sive Bus Read operation will show the bit is still ‘0’.
One of the Erase commands must be used to set
all the bits in a block or in the whole memory from
’0’ to ’1’.
Table 10. Status Register BitsNote: Unspecified data bits should be ignored.
11/22
M29F400BT, M29F400BB
Erase Timer Bit (DQ3). The Erase Timer Bit can
be used to identify the start of Program/Erase
Controller operation during a Block Erase com-
mand. Once the Program/Erase Controller starts
erasing the Erase Timer Bit is set to ’1’. Before the
Program/Erase Controller starts the Erase Timer
Bit is set to ’0’ and additional blocks to be erased
may be written to the Command Interface. The
Erase Timer Bit is output on DQ3 when the Status
Register is read.
Alternative Toggle Bit (DQ2). The Alternative
Toggle Bit can be used to monitor the Program/
Erase controller during Erase operations. The Al-
ternative Toggle Bit is output on DQ2 when the
Status Register is read.
During Chip Erase and Block Erase operations the
Toggle Bit changes from ’0’ to ’1’ to ’0’, etc., with
successive Bus Read operations from addresses
within the blocks being erased. Once the operation
completes the memory returns to Read mode.
During Erase Suspend the Alternative Toggle Bit
changes from ’0’ to ’1’ to ’0’, etc. with successive
Bus Read operations from addresses within the
blocks being erased. Bus Read operations to ad-
dresses within blocks not being erased will output
the memory cell data as if in Read mode.
After an Erase operation that causes the Error Bit
to be set the Alternative Toggle Bit can be used to
identify which block or blocks have caused the er-
ror. The Alternative Toggle Bit changes from ’0’ to
’1’ to ’0’, etc. with successive Bus Read Opera-
tions from addresses within blocks that have not
erased correctly. The Alternative Toggle Bit does
not change if the addressed block has erased cor-
rectly.
