M29W641DH datasheet(13/42 Pages) STMICROELECTRONICS

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M29W641DH, M29W641DL, M29W641DU

the lowest address block. The 50µs timer restarts

when an additional block is selected. The Status

eration. See the Status Register section 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

command. Typical block erase times are given in

Table 4. 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 32 KWord block (Extend-

ed Block) that can only be accessed using the En-

ter Extended Block command. Three Bus write

cycles are required to issue the Extended Block

command. Once the command has been issued

the device enters Extended Block mode where all

Bus Read or Write operations to the Boot Block

addresses access the Extended Block. The Ex-

tended Block (with the same address as the Boot

Blocks) cannot be erased, and can be treated as

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

tended Block mode the Boot Blocks are not acces-

sible.

To exit from the Extended Block mode the Exit Ex-

tended Block command must be issued.

The Extended Block can be protected, however

once protected the protection cannot be undone.

Exit Extended Block Command

The Exit Extended Block command is used to exit

from the Extended Block mode and return the de-

vice to Read mode. Four Bus Write operations are

required to issue the command.

Block Protect and Chip Unprotect Commands

Groups of blocks can be protected against acci-

dental Program or Erase. The whole chip can be

unprotected to allow the data inside the blocks to

be changed.

Block Protect and Chip Unprotect operations are

described in Appendix D.

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