M29W640DB datasheet(14/49 Pages) STMICROELECTRONICS

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M29W640DT, M29W640DB

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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 6.. 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

the last block. The 50µs timer restarts when an ad-

ditional block is selected. The Status Register can

be read after the sixth Bus Write operation. See

the Status Register section for details on how to

identify if the Program/Erase Controller has start-

ed 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

command. Typical block erase times are given in

Table 6.. All Bus Read operations 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

the Erase Suspend Latency time of the Erase Sus-

pend Command being issued. Once the Program/

Erase Controller has stopped the memory will be

set to Read mode and the Erase will be suspend-

ed. If the Erase Suspend command is issued dur-

ing the period when the memory is waiting for an

additional block (before the Program/Erase Con-

troller starts) then the Erase is suspended immedi-

ately and will start immediately when the Erase

Resume Command is issued. It is not possible to

select any further blocks to erase 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. If any attempt is made to

program in a protected block or in the suspended

block then the Program command is ignored and

the data remains unchanged. The Status Register

is not read and no error condition is given. Read-

ing from blocks that are being erased will output

the Status Register.

It is also possible to issue the Auto Select, Read

CFI Query and Unlock Bypass commands during

an Erase Suspend. The Read/Reset command

must be issued to return the device to Read Array

mode before the Resume command will be ac-

cepted.

Erase Resume Command.

The Erase Resume command must be used to re-

start the Program/Erase Controller after an Erase

Suspend. The device must be in Read Array mode

before the Resume command will be accepted. An

erase can be suspended and resumed more than

once.

Enter Extended Block Command

The device has an extra 64 KByte block (Extended

Block) that can only be accessed using the Enter

Extended Block command. Three Bus write cycles

are required to issue the Extended Block com-

mand. Once the command has been issued the

device enters Extended Block mode where all Bus

Read or Write operations to the Boot Block ad-

dresses access the Extended Block. The Extend-

ed Block (with the same address as the Boot

Blocks) cannot be erased, and can be treated as

one-time programmable (OTP) memory. In Ex-

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