AM29SL800D datasheet(19/46 Pages) AMD

19 / 46 page

D A TA

SH EE T

January 23, 2007 27546A6

Am29SL800D

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 between additional

sector erase commands can be assumed 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 period 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 sector

erase timer has timed out. (See DQ3: Sector Erase

Timer‚ on page 22.) 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 ignored. 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 integrity.

When the Embedded Erase algorithm is complete, the

device 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#. (Refer to Write Operation Status‚ on

page 20 for information on these status bits.)

Figure 4, on page 18 illustrates the algorithm for the

erase operation. Refer to the Table 16 on page 39for

parameters, and to Figure 18, on page 33 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 sector

erase operation, including the 50 µs time-out period

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 operation.

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 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 ter-

minates 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 definitions apply.

Reading at any address 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-sus-

pended. See Write Operation Status‚ on page 20 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 determine

the status of the program operation using the DQ7 or

DQ6 status bits, just as in the standard program oper-

ation. See Write Operation Status‚ on page 20 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 Sequence‚

on page 15 for more information.

The system must write the Erase Resume command

(address 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 erasing.

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