M420000022 datasheet(29/64 Pages) AMD

29 / 64 page

May 19, 2003

Am42DL32x4G

PR ELI M I NARY

Figure 3.

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. Tables 14 and

16 show the address and data requirements for the

chip erase command sequence.

When the Embedded Erase algorithm is complete,

that bank returns to reading array data and addresses

are no longer latched. The system can determine the

status of the erase operation by using DQ7, DQ6,

DQ2, or RY/BY#. Refer to the Write Operation Status

section for information on these status bits. Note that

the SecSi Sector, autoselect, and CFI functions are

unavailable when an erase operation in is progress.

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 4 illustrates the algorithm for the erase opera-

t i on. Refer to the Fl as h Eras e and Program

Operations tables in the AC Characteristics section for

par am et er s , and F i gu r e 20 s ec t ion fo r tim i ng

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. Tables 14 and 16

show the address and data requirements for the sec-

tor erase command sequence.

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 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

address and command following the exceeded

time-out may or may not be accepted. It is recom-

mended that processor interrupts be disabled during

this time to ensure all commands are accepted. The

interrupts can be re-enabled after the last Sector

Erase command is written. Any command other than

Se ct or E rase or E rase Su spend dur ing the

time-out period resets that bank to reading array

data. The system must rewrite the command se-

quence and any additional addresses and commands.

Note that the SecSi Sector, autoselect, and CFI func-

tions 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 Tables 14 and 16 for program command

sequence.

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