AM29PDS322DB40WMIN datasheet(26/51 Pages) AMD

26 / 51 page

Am29PDS322D

23569A5 December 4, 2006

D A TA

SH EE T

When the Embedded Erase algorithm is complete, the

device returns to the read mode 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.

Any commands written during the chip erase operation

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

mediately terminates the erase operation. If that oc-

curs, the chip erase command sequence should be

reinitiated once the device has returned to reading

array data, to ensure data integrity.

Figure 6 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 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 fol-

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

the sector erase command. Table 10 shows the ad-

dress and data requirements for the sector erase com-

mand 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 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.

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. Note that while the Embedded

Erase operation is in progress, the system can read

data from the non-erasing sector. The system can de-

termine the status of the erase operation by reading

DQ7, DQ6, DQ2, or RY/BY# in the erasing sector.

Refer to the Write Operation Status section for infor-

mation 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 6 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 20 section for timing diagrams.

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 µs to suspend the erase operation. How-

ever, when the Erase Suspend command is written

during the sector erase time-out, the device immedi-

ately terminates the time-out period and suspends 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.) Note that un-

lock bypass programming is not allowed when the

device is erase-suspended.

Reading at any address within erase-suspended sec-

tors produces status information on DQ7–DQ0. The

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

d e t e r m in e if a se ct or is a c t i ve ly e rasin g or is

erase-suspended. Refer to the Write Operation Status

section for information on these status bits.

After an erase-suspended program operation is com-

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

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