AM29DL800B datasheet(20/46 Pages) AMD

20 / 46 page

Am29DL800B

21519C4 December 4, 2006

D A TA

SH EET

Note: See Table 5 for program command sequence.

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. Table 5 shows

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 sta-

tus 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

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-

tion. Refer to the Erase and Program Operations tables

in the AC Characteristics section for parameters, and

Figure 18 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 un-

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

additional unlock cycles are written, and are then fol-

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

the sector erase command. Table 5 shows the address

and data requirements for the sector 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 within the bank may be written. Loading the

sector erase buffer may be done in any sequence, and

the number of sectors may be from one sector to all

sectors. The time between these additional cycles must

be less than 50 µs, otherwise the last address and

command may not be accepted, and erasure may be-

gin. It is recommended 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 Sector Erase or Erase Suspend during

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.

The system can monitor DQ3 (in the erasing bank) to

determine if the sector erase timer has timed out (See

the section on DQ3: Sector Erase Timer.). The time-out

begins from the rising 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

no longer latched. Note that while the Embedded Erase

operation is in progress, the system can read data from

the non-erasing bank. The system can determine the

status of the erase operation by reading DQ7, DQ6,

DQ2, or RY/BY# in the erasing bank. Refer to the Write

Operation Status section for information on these sta-

tus bits.

Once the sector erase operation has begun, only the

Erase Suspend command is valid. All other commands

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

START

Write Program

Command Sequence

Data Poll

from System

Verify Data?

Yes

Last Address?

Yes

Programming

Completed

Increment Address

Embedded

Program

algorithm

in progress

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