AM29PDL128G datasheet(39/71 Pages) AMD

39 / 71 page

Am29PDL128G

October 28, 2004

P R E L IM IN A R Y

the status of the erase operation by reading DQ7,

DQ6, DQ2, or RY/BY# in the erasing bank. See “Write

Operation Status” on page 46 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. Note: A hardware reset immedi-

ately 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 4 illustrates the algorithm for the erase opera-

tion. Refer to the “Erase and Program Operations”

tables in “AC Characteristics” on page 53 for parame-

ters, and Figure 18 for timing diagrams.

1. See Table 14 and Table 14 for erase command sequence.

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

timer

Figure 5.

Erase Operation

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. 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. Addresses are “don’t-cares” when

writing 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.

See “Write Operation Status” on page 46 for informa-

tion 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 Double Word/Word Program

operation. See “Write Operation Status” on page 46

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 reverts to the Erase Sus-

pend mode, and is ready for another valid operation.

See “Autoselect Mode” on page 21 and “Autoselect

Command Sequence” on page 35 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.

Password Program Command

The Password Program Command permits program-

ming the password that is used as part of the hard-

ware protection scheme. The actual password is

64-bits long. Depending upon the state of the WORD#

pin, multiple Password Program Commands are re-

quired. For a x16 bit data bus, 4 Password Program

commands are required to program the password. For

a x32 bit data bus, 2 Password Program commands

are required. The user must enter the unlock cycle,

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

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