M29W641DH datasheet(12/42 Pages) STMICROELECTRONICS

12 / 42 page

M29W641DH, M29W641DL, M29W641DU

12/42

The first bus cycle sets up the Double Word

Program Command.

The second bus cycle latches the Address and

the Data of the first word to be written.

The third bus cycle latches the Address and the

Data of the second word to be written and starts

the Program/Erase Controller.

Only one bank can be programmed at any one

time. The other bank must be in Read mode or

Erase Suspend.

Programming should not be attempted when VPP

is not at VPPH.

After programming has started, Bus Read opera-

tions in the Bank being programmed output the

Status Register content, while Bus Read opera-

tions to the other Bank output the contents of the

memory array.

After the program operation has completed the

memory will return to the Read mode, unless an

error has occurred. When an error occurs Bus

Read operations to the Bank where the command

was issued will continue to output the Status Reg-

ister. A Read/Reset command must be issued to

reset the error condition and return to Read mode.

Note that the Fast Program commands cannot

change a bit set at ’0’ back to ’1’. 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’.

Typical Program times are given in Table 4, Pro-

gram, Erase Times and Program, Erase Endur-

ance Cycles.

Unlock Bypass Command

The Unlock Bypass command is used in conjunc-

tion with the Unlock Bypass Program command to

program the memory faster than with the standard

program commands. When the cycle time to the

device is long (as with some EPROM program-

mers) considerable time saving can be made by

using these commands. Three Bus Write opera-

tions are required to issue the Unlock Bypass

command.

Once the Unlock Bypass command has been is-

sued the memory enters Unlock Bypass mode.

When in this mode the memory can be read as if

in Read mode.

When VPPH is applied to the VPP pin the memory

automatically enters the Unlock Bypass mode and

the Unlock Bypass Program command can be is-

sued immediately.

Unlock Bypass Program Command

The Unlock Bypass Program command can be

used to program one address in the memory array

at a time. The command requires two Bus Write

operations, the final write operation latches the ad-

dress and data, and starts the Program/Erase

Controller.

A Program operation initiated by issuing the Un-

lock Bypass Program command is identical to a

Program operation initiated by issuing the Pro-

gram command. It cannot be aborted and a Bus

Read operation will output the Status Register.

See the Program Command paragraph for further

details.

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. Read/

Reset command does not exit from Unlock Bypass

Mode.

Chip Erase Command

The Chip Erase command can be used to erase

the entire chip. Six Bus Write operations are re-

quired 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, including the Erase Suspend com-

mand. It is not possible to issue any command to

abort the operation. Typical chip erase times are

given in Table 4. All Bus Read operations during

the Chip Erase operation will output the Status

tion 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 command can be used to erase

a list of one or more blocks. Six Bus Write opera-

tions 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 addition-

al block must therefore be selected within 50µs of

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