AM29SL400CB100REF datasheet(19/44 Pages) SPANSION

19 / 44 page

March 3, 2005

Ad vance

Inform ati o n

When the Embedded Erase algorithm is complete,

the device returns to reading array data and ad-

dresses are no longer latched. The system can deter-

mine the status of the erase operation by using DQ7,

DQ6, DQ2, or RY/BY#. (Refer to Write Operation

Status‚ on page 18 for information on these status

bits.)

Figure 4 illustrates the algorithm for the erase opera-

tion. Refer to the Erase/Program Operations‚ on

page 30 for parameters, and to Figure 18‚ on

page 32 for timing diagrams.

Erase Suspend/Erase Resume Commands

The Erase Suspend command allows the system 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 algo-

rithm. Writing the Erase Suspend command during

the Sector Erase time-out immediately terminates

the time-out period and suspends the erase opera-

tion. Addresses are don’t-cares when writing the

Erase Suspend command.

When the Erase Suspend command is written during

a sector erase operation, the device requires a maxi-

mum 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

system can read array data from or program data to

any sector not selected for erasure. (The device

erase suspends all sectors selected for erasure.)

Normal read and write timings and command defini-

tion s a pply. Re ading at any addr ess within

erase-suspended sectors produces status data on

DQ7–DQ0. The system can use DQ7, or DQ6 and

DQ2 together, to determine if a sector is actively

erasing or is erase-suspended. See Write Operation

Status‚ on page 18 for information on these status

bits.

After an erase-suspended program operation is com-

plete, the system can once again read array data

within non-suspended sectors. The system can de-

termine the status of the program operation using

the DQ7 or DQ6 status bits, just as in the standard

program operation. See Write Operation Status‚ on

page 18 for more information.

The system may also write the autoselect command

sequence when the device is in the Erase Suspend

mode. The device allows reading autoselect codes

even at addresses within erasing sectors, since the

codes are not stored in the memory array. When the

device exits the autoselect mode, the device reverts

to the Erase Suspend mode, and is ready for another

valid operation. See Autoselect Command Se-

quence‚ on page 15 for more information.

The system must write the Erase Resume command

(address bits are “don’t care”) to exit the erase sus-

pend mode and continue the sector erase operation.

Further writes of the Resume command are ignored.

Another Erase Suspend command can be written

after the device has resumed erasing.

Notes:

1. See Table 5 on page 18 for erase command sequence.

2. See DQ3: Sector Erase Timer‚ on page 21 for more in-

formation.

Figure 4. Erase Operation

START

Write Erase

Command Sequence

Data Poll

from System

Data = FFh?

Yes

Erasure Completed

Embedded

Erase

algorithm

in progress

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