D640D90VF datasheet(27/54 Pages) AMD

27 / 54 page

December 13, 2005

Am29DL640D

Figure 4.

Program Operation

Chip Erase Command Sequence

Chip erase is a six bus cycle operation. The chip erase

command sequence is initiated by writing two unlock

cycles, followed by a set-up command. Two additional

unlock write cycles are then followed by the chip erase

command, which in turn invokes the Embedded Erase

algorithm. The device does not require the system to

preprogram prior to erase. The Embedded Erase algo-

rithm automatically preprograms and verifies the entire

memory for an all zero data pattern prior to electrical

erase. The system is not required to provide any con-

trols or timings during these operations. Table 12

shows the address and data requirements for the chip

erase command sequence. Note that the Secured Sili-

con Sector, autoselect, and CFI functions are

unavailable when an erase operation in is progress.

When the Embedded Erase algorithm is complete,

that bank returns to the read mode and addresses are

no longer latched. The system can determine the sta-

tus of the erase operation by using DQ7, DQ6, DQ2,

or RY/BY#. Refer to the Write Operation Status sec-

tion for information on these status bits.

Any commands written during the chip erase operation

are ignored. However, note that a hardware reset im-

mediately terminates the erase operation. If that

occurs, the chip erase command sequence should be

reinitiated once that bank has returned to reading

array data, to ensure data integrity.

Figure 5 illustrates the algorithm for the erase opera-

tion. Refer to the Erase and Program Operations

tables in the AC Characteristics section for parame-

ters, and Figure 20 section for timing diagrams.

Sector Erase Command Sequence

Sector erase is a six bus cycle operation. The sector

erase command sequence is initiated by writing two

unlock cycles, followed by a set-up command. Two ad-

ditional unlock cycles are written, and are then

followed by the address of the sector to be erased, and

the sector erase command. Table 12 shows the ad-

dress and data requirements for the sector erase

command sequence. Note that the Secured Silicon

Sector, autoselect, and CFI functions are unavailable

when an erase operation in is progress.

The device does not require the system to preprogram

prior to erase. The Embedded Erase algorithm auto-

matically programs and verifies the entire memory for

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 80 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 80

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

that bank to the read mode. The system must rewrite

the command sequence and any additional addresses

and commands. Note that the Secured Silicon Sector,

autoselect, and CFI functions are unavailable when an

erase operation in is 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

bank returns to reading array data and addresses are

START

Write Program

Command Sequence

Data Poll

from System

Verify Data?

Yes

Last Address?

Yes

Programming

Completed

Increment Address

Embedded

Program

algorithm

in progress

Note: See Table 12 for program command sequence.

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