AM29SL400CB100REF datasheet(19/44 Pages) AMD

19 / 44 page

January 23, 2007 Am29SL400C_00_A6

Am29SL400C

D A TA

SH EE T

The system can monitor DQ3 to determine if the sector

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 commands are ig-

nored. Note that a hardware reset during the sector erase

operation immediately terminates the operation. The Sector

Erase command sequence should be reinitiated once the

device has returned to reading array data, to ensure data in-

tegrity.

When the Embedded Erase algorithm is complete, the de-

vice 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#. (Re-

fer to Write Operation Status‚ on page 19 for information on

these status bits.)

Figure 4 illustrates the algorithm for the erase operation.

Refer to the Erase/Program Operations‚ on page 30 for pa-

rameters, 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 pro-

gram data to, any sector not selected for erasure. This com-

mand is valid only during the sector erase operation,

including the 50 µs time-out period during the sector erase

command sequence. The Erase Suspend command is ig-

nored if written during the chip erase operation or Embedded

Program algorithm. Writing the Erase Suspend command

during the Sector Erase time-out immediately terminates the

time-out period and suspends the erase operation. Ad-

dresses are don’t-cares when writing the Erase Suspend

command.

When the Erase Suspend command is written during a sec-

tor erase operation, the device requires a maximum of 20 µs

to suspend the erase operation. However, when the Erase

Suspend command is written during the sector erase

time-out, the device immediately terminates the time-out pe-

riod 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 definitions apply. Reading at any address within

eras e-su spe n de d se ctors pro du c es status da ta o n

DQ7–DQ0. The system can use DQ7, or DQ6 and DQ2 to-

gether, to determine if a sector is actively erasing or is

erase-suspended. See Write Operation Status‚ on page 19

for information on these status bits.

After an erase-suspended program operation is complete,

the system can once again read array data within non-sus-

pended sectors. The system can determine 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 19 for more information.

The system may also write the autoselect command se-

quence 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 (ad-

dress bits are “don’t care”) to exit the erase suspend 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 eras-

ing.

Notes:

See Table 5 on page 18 for erase command sequence.

See DQ3: Sector Erase Timer‚ on page 21 for more information.

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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