D640D90VF datasheet(28/54 Pages) AMD

28 / 54 page

Am29DL640D

December 13, 2005

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 de-

termine 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 status bits.

Once the sector erase operation has begun, only the

Erase Suspend command is valid. All other com-

mands are ignored. However, note that a hardware

reset immediately terminates the erase operation. If

that occurs, the sector erase command sequence

should be reinitiated once that bank has returned to

reading array data, to ensure data integrity.

Figure 5 illustrates the algorithm for the erase opera-

tion. Refer to the Erase and Program Operations

tables in the AC Characteristics section for parame-

ters, and Figure 20 section for timing diagrams.

Erase Suspend/Erase Resume

Commands

The Erase Suspend command, B0h, allows the sys-

tem to interrupt a sector erase operation and then read

data from, or program data to, any sector not selected

for erasure. The bank address is required when writing

this command. This command is valid only during the

sector erase operation, including the 80 µs time-out

period during the sector erase command sequence.

The Erase Suspend command is ignored if written dur-

ing the chip erase operation or Embedded Program

algorithm.

When the Erase Suspend command is written during

the sector erase operation, the device requires a max-

imum of 20 µs to suspend the erase operation.

However, when the Erase Suspend command is writ-

ten during the sector erase time-out, the device

immediately terminates the time-out period and sus-

pends the er ase oper ation. Addresses are

“don’t-ca res” when wr iting the Erase suspend

command.

After the erase operation has been suspended, the

bank enters the erase-suspend-read mode. The sys-

tem can read data from or program data to any sector

not selected for erasure. (The device “erase sus-

pends” all sectors selected for erasure.) Reading at

any address within erase-suspended sectors pro-

duces status information 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.

Refer to the Write Operation Status section for infor-

mation on these status bits.

After an erase-suspended program operation is com-

plete, the bank returns to the erase-suspend-read

mode. The system can determine the status of the

program operation using the DQ7 or DQ6 status bits,

just as in the standard Byte Program operation.

Refer to the Write Operation Status section for more

information.

In the erase-suspend-read mode, the system can also

issue the autoselect command sequence. 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 au-

toselect mode, the device rever ts to the Erase

Suspend mode, and is ready for another valid opera-

tion. Refer to the Autoselect Mode and Autoselect

Command Sequence sections for details.

To resume the sector erase operation, the system

must write the Erase Resume command (address bits

are don’t care). The bank address of the erase-sus-

pended bank is required when writing this command.

Further writes of the Resume command are ignored.

Another Erase Suspend command can be written after

the chip has resumed erasing.

Figure 5.

Erase Operation

START

Write Erase

Command Sequence

(Notes 1, 2)

Data Poll to Erasing

Bank from System

Data = FFh?

Yes

Erasure Completed

Embedded

Erase

algorithm

in progress

Notes:

1. See Table 12 for erase command sequence.

2. See the section on DQ3 for information on the sector

erase timer.

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