M29W641D View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

M29W641D

64 Mbit (4Mb x16, Uniform Block) 3V Supply Flash Memory

STMicroelectronics 

M29W641DH, M29W641DL, M29W641DU

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.

See Table 3 for a summary of the commands.

Read/Reset Command

The Read/Reset command 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.

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. If the Read/Reset command is issued

during the timeout of a Block erase operation then

the memory will take up to 10µs to abort. During

the abort period no valid data can be read from the

memory. The Read/Reset command will not abort

an Erase operation when issued while in Erase

Suspend.

Auto Select Command

The Auto Select command is used to read the

Manufacturer Code, the Device Code, the Block

Protection Status and the Extended Memory Block

Verify Code. Three consecutive Bus Write opera-

tions are required to issue the Auto Select com-

mand. Once the Auto Select command is issued

the memory remains in Auto Select mode until a

Read/Reset command is issued. Read CFI Query

and Read/Reset commands are accepted in Auto

Select mode, all other commands are ignored.

In 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 ST-

Microelectronics 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 M29W641D is 22C7h.

The Block Protection Status of each block can be

read using a Bus Read operation with A0 = VIL,

A1 = VIH, and A12-A21 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.

Read CFI Query Command

The Read CFI Query Command is used to read

data from the Common Flash Interface (CFI)

Memory Area. This command is valid when the de-

vice is in the Read Array mode, or when the device

is in Autoselected mode.

One Bus Write cycle is required to issue the Read

CFI Query Command. Once the command is is-

sued subsequent Bus Read operations read from

the Common Flash Interface Memory Area.

The Read/Reset command must be issued to re-

turn the device to the previous mode (the Read Ar-

ray mode or Autoselected mode). A second Read/

Reset command would be needed if the device is

to be put in the Read Array mode from Autoselect-

ed mode.

See Appendix B, Table 18 to Table 23 for details

on the information contained in the Common Flash

Interface (CFI) memory area.

Program Command

The Program command can be used to program a

value to one address in the memory array at a

time. The command requires four Bus Write oper-

ations, the final write operation latches the ad-

dress and data, and starts the Program/Erase

Controller.

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-

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’.

Fast Program Commands

There is a Fast Program command available to im-

prove the programming throughput, by writing sev-

eral adjacent words or bytes in parallel: the Double

Word Program command.

Double Word Program Command. The Double

Word Program command is used to write a page

of two adjacent words in parallel. The two words

must differ only for the address A0.

Three bus write cycles are necessary to issue the

Double Word Program command.

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