AM29LV640MH datasheet(34/62 Pages) AMD

34 / 62 page

Am29LV640MH/L

December 14, 2005

DA TA SH EET

Erase Suspend/Erase Resume

Commands

The Erase Suspend command, B0h, allows the sys-

tem to interrupt a sector erase operation and then read

data from, or program data to, any sector not selected

for erasure. This command is valid only during the sec-

tor erase operation, including the 50 µs time-out pe-

riod during the sector erase command sequence. The

Erase Suspend command is ignored if written during

the chip erase operation or Embedded Program

algorithm.

When the Erase Suspend command is written during

the sector erase operation, the device requires a max-

imum of 20 (typical 5 µs) to suspend the erase opera-

tion. However, when the Erase Suspend command is

written during the sector erase time-out, the device im-

mediately terminates the time-out period and sus-

pends the erase operation.

After the erase operation has been suspended, the

device enters the erase-suspend-read mode. The sys-

tem can read data from or program data to any sector

not selected for erasure. (The device “erase sus-

pends” all sectors selected for erasure.) Reading at

any address within erase-suspended sectors pro-

duces status information on DQ7–DQ0. The system

can use DQ7, or DQ6 and DQ2 together, to determine

if a sector is actively erasing or is erase-suspended.

Refer to the Write Operation Status section for infor-

mation on these status bits.

After an erase-suspended program operation is com-

plete, the device returns to the erase-suspend-read

mode. The system can determine the status of the

program operation using the DQ7 or DQ6 status bits,

just as in the standard word program operation.

Refer to the Write Operation Status section for more

information.

In the erase-suspend-read mode, the system can also

issue the autoselect command sequence. Refer to the

Autoselect Mode and Autoselect Command Sequence

sections for details.

To resume the sector erase operation, the system

must write the Erase Resume command. Fur ther

writes of the Resume command are ignored. Another

Erase Suspend command can be written after the chip

has resumed erasing.

Note: During an erase operation, this flash device per-

forms multiple internal operations which are invisible

to the system. When an erase operation is suspended,

any of the internal operations that were not fully com-

pleted must be restarted. As such, if this flash device

is continually issued suspend/resume commands in

rapid succession, erase progress will be impeded as a

function of the number of suspends. The result will be

a longer cumulative erase time than without suspends.

Note that the additional suspends do not affect device

reliability or future performance. In most systems rapid

erase/suspend activity occurs only briefly. In such

cases, erase performance will not be significantly im-

pacted.

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