M29W400DT ST Microelectronics, M29W400DT Datasheet - Page 12

• Manufacturer Part Number: M29W400DT
• Description: 4 Mbit (512Kb x8 or 256Kb x16 / Boot Block) 3V Supply Flash Memory
• Manufacturer: ST Microelectronics

M29W400DT, M29W400DB
Table 3. Bus Operations, BYTE = V
Note: X = V
COMMAND INTERFACE
All 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 5, or 6, 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, unless other-
wise stated. 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.
The Read/Reset Command can be issued, be-
tween Bus Write cycles before the start of a pro-
gram or erase operation, to return the device to
read mode. Once the program or erase operation
has started the Read/Reset command is no longer
accepted. The Read/Reset command will not
abort an Erase operation when issued while in
Erase Suspend.
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 = V
12/36
Bus Read
Bus Write
Output Disable
Standby
Read Manufacturer
Code
Read Device Code
Operation
IL
or V
IL
and A1 = V
IH
.
V
V
V
V
V
E
X
IH
IL
IL
IL
IL
IL
. The other address bits
V
V
V
V
V
G
X
IH
IH
IL
IL
IL
IH
V
V
V
V
V
W
X
IH
IH
IH
IH
IL
Cell Address
Command Address
X
X
A0 = V
Others V
A0 = V
Others V
Address Inputs
IL
IH
, A1 = V
, A1 = V
IL
IL
may be set to either V
Code for STMicroelectronics is 0020h.
The Device Code can be read using a Bus Read
operation with A0 = V
address bits may be set to either V
Device Code for the M29W400DT is 00EEh and
for the M29W400DB is 00EFh.
The Block Protection Status of each block can be
read using a Bus Read operation with A0 = V
A1 = V
the block. The other address bits may be set to ei-
ther V
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 4. 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-
A0-A17
or V
or V
IH
IH
IL
IL
IL
IH
, A9 = V
, A9 = V
or V
, and A12-A17 specifying the address of
IH
. If the addressed block is protected
ID
ID
,
,
IL
IH
DQ15A–1, DQ14-DQ0
00EEh (M29W400DT)
00EFh (M29W400DB)
Data Inputs/Outputs
or V
and A1 = V
Data Output
IH
Data Input
. The Manufacturer
0020h
Hi-Z
Hi-Z
IL
IL
or V
. The other
IH
. The
IL
,