AM29LV800T datasheet(17/48 Pages) AMD

17 / 48 page

Am29LV800T/Am29LV800B

PRELIMINARY

Automatic sector erase operations begin on the rising

edge of the WE (or CE) pulse of the last sector erase

command issued, and once the 80

µs time-out window

has expired. The status of the sector erase operation

can be determined three ways:

s DATA Polling of DQ7

s Checking the status of the toggle bit DQ6

s Checking the status of the RY/BY pin

Further status of device activity during the sector erase

operation can be determined using toggle bits DQ2 and

DQ3.

Figure 8 illustrates the Embedded Erase Algorithm,

using a typical command sequence and bus operations.

Erase Suspend

The Erase Suspend command allows the user to inter-

rupt a Sector Erase operation and then perform data

read or programs in a sector not being erased. This

command is applicable only during the Sector Erase

operation, which includes the time-out period for Sector

Erase. The Erase Suspend command will be ignored if

written during the execution of the Chip Erase opera-

tion or Embedded Program Algorithm (but will reset the

chip if written improperly during the command se-

quences.) Writing the Erase Suspend command during

the Sector Erase time-out results in immediate termina-

tion of the time-out period and suspension of the erase

operation. Once in Erase Suspend, the device is avail-

able for read (note that in the Erase Suspend mode, the

Reset/Read command is not required for read opera-

tions and is ignored) or program operations in sectors

not being erased. Any other command written during

the Erase Suspend mode will be ignored, except for the

Erase Resume command. Writing the Erase Resume

command resumes the sector erase operation. The ad-

dresses are “don’t cares” when writing the Erase Sus-

pend or Erase Resume command.

When the Erase Suspend command is written during a

Sector Erase operation, the chip will take between 0.1

µs and 20 µs to actually suspend the operation and go

into erase suspended read mode (pseudo-read mode),

at which time the user can read or program from a sec-

tor that is not erase suspended. Reading data in this

mode is the same as reading from the standard read

mode, except that the data must be read from sectors

that have not been erase suspended.

Successively reading from the erase-suspended sector

while the device is in the erase-suspend-read mode will

cause DQ2 to toggle. Polling DQ2 on successive reads

from a given sector provides the system the ability to

determine if a sector is in Erase Suspend.

After entering the erase-suspend-read mode, the user

can program the device by writing the appropriate com-

mand sequence for Byte Program. This program mode

is known as the erase suspend-program mode. Again,

programming in this mode is the same as programming

in the regular Byte Program mode, except that the data

must be programmed to sectors that are not erase sus-

pended. Successively reading from the erase sus-

pended sector while the device is in the erase

suspend-program mode will cause DQ2 to toggle.

Completion of the erase suspend operation can be de-

termined two ways:

s Checking the status of the toggle bit DQ2

s Checking the status of the RY/BY pin

To resume the operation of Sector Erase, the Resume

command (30h) should be written. Any further writes of

the Resume command at this point will be ignored. How-

ever, another Erase Suspend command can be written

after the device has resumed sector erase operations.

When the erase operation has been suspended, the de-

vice defaults to the erase-suspend-read mode. Reading

data in this mode is the same as reading from the stan-

dard read mode except that the data must be read from

sectors that have not been erase-suspended.

To resume the operation of Sector Erase, the Resume

command (30h) should be written. Any further writes of

the Resume command at this point will be ignored. An-

other Erase Suspend command can be written after the

chip has resumed erasing.

AM29LV800T Datasheet(PDF) 17 Page - Advanced Micro Devices

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