AM29LV640MH datasheet(33/62 Pages) AMD

33 / 62 page

December 14, 2005

Am29LV640MH/L

DA TA SH EET

an all zero data pattern prior to electrical erase. The

system is not required to provide any controls or tim-

ings during these operations.

After the command sequence is written, a sector erase

time-out of 50 µs occurs. During the time-out period,

additional sector addresses and sector erase com-

mands may be written. Loading the sector erase buffer

may be done in any sequence, and the number of sec-

tors may be from one sector to all sectors. The time

between these additional cycles must be less than 50

µs, otherwise erasure may begin. Any sector erase ad-

dress and command following the exceeded time-out

may or may not be accepted. It is recommended that

processor interrupts be disabled during this time to en-

sure all commands are accepted. The interrupts can

be re-enabled after the last Sector Erase command is

written. Any command other than Sector Erase or

Erase Suspend during the time-out period resets

the device to the read mode. The system must re-

write the command sequence and any additional ad-

dresses and commands. Note that the SecSi Sector,

autoselect, and CFI functions are unavailable when an

erase operation is in progress.

The system can monitor DQ3 to determine if the sec-

tor erase timer has timed out (See the section on DQ3:

Sector Erase Timer.). The time-out begins from the ris-

ing edge of the final WE# pulse in the command

sequence.

When the Embedded Erase algorithm is complete, the

device returns to reading array data and addresses

are no longer latched. The system can determine the

status of the erase operation by reading DQ7, DQ6, or

DQ2 in the erasing sector. Refer to the Write Opera-

tion Status section for information on these status bits.

Once the sector erase operation has begun, only the

Erase Suspend command is valid. All other com-

mands are ignored. However, note that a hardware

reset immediately terminates the erase operation. If

that occurs, the sector erase command sequence

should be reinitiated once the device has returned to

reading array data, to ensure data integrity.

Figure 7 illustrates the algorithm for the erase opera-

tion. Refer to the Erase and Program Operations ta-

bles in the AC Characteristics section for parameters,

and Figure 19 section for timing diagrams.

Notes:

1. See Tables 10 and 11 for erase command sequence.

2. See the section on DQ3 for information on the sector erase timer.

Figure 7.

Erase Operation

START

Write Erase

Command Sequence

(Notes 1, 2)

Data Poll to Erasing

Bank from System

Data = FFh?

Yes

Erasure Completed

Embedded

Erase

algorithm

in progress

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