AM29SL400CB100REF datasheet(18/44 Pages) SPANSION

18 / 44 page

March 3, 2005

Ad vance

Inform ati o n

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 re-

quire the system to preprogram prior to erase. The

Embedded Erase algorithm automatically prepro-

grams 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 timings dur-

ing these operations. Table 5 on page 18 shows the

address and data requirements for the chip erase

command sequence.

Any commands written to the chip during the Em-

bedded Erase algorithm are ignored. Note that a

hardware reset during the chip erase operation im-

mediately terminates the operation. The Chip Erase

command sequence should be reinitiated once the

device has returned to reading array data, to ensure

data integrity The system can determine the status

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

RY/BY#. See Write Operation Status‚ on page 18 for

information on these status bits. When the Embed-

ded Erase algorithm is complete, the device returns

to reading array data and addresses are no longer

latched.

Figure 4‚ on page 17 illustrates the algorithm for the

erase operation. See Erase/Program Operations‚ on

page 30 for parameters, and to Figure 18 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

additional unlock write cycles are then followed by

the address of the sector to be erased, and the sec-

tor erase command. Table 5 on page 18 shows the

address and data requirements for the sector erase

command sequence.

The device does not require the system to prepro-

gram the memory prior to erase. The Embedded

Erase algorithm automatically programs and verifies

the sector for an all zero data pattern prior to electri-

cal erase. The system is not required to provide any

controls or timings during these operations.

After the command sequence is written, a sector

erase time-out of 50 µs begins. During the time-out

period, additional sector addresses and sector erase

commands may be written. Loading the sector erase

buffer may be done in any sequence, and the num-

ber 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 com-

mand might 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. If the time be-

tween additional sector erase commands can be as-

sumed to be less than 50 µs, the system need not

monitor DQ3. Any command other than Sector

Erase or Erase Suspend during the time-out pe-

riod resets the device to reading array data.

The system must rewrite the command sequence

and any additional sector addresses and commands.

The system can monitor DQ3 to determine if the sec-

tor erase timer has timed out. (See the “DQ3: Sector

Erase Timer” section.) The time-out begins from the

rising edge of the final WE# pulse in the command

sequence.

Once the sector erase operation has begun, only the

Erase Suspend command is valid. All other com-

mands are ignored. Note that a hardware reset

during the sector erase operation immediately termi-

nates the operation. The Sector Erase command se-

quence should be reinitiated once the device has

returned to reading array data, to ensure data integ-

rity.

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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