AM29BL802C datasheet(20/46 Pages) AMD

20 / 46 page

Am29BL802C

22371C7 November 3, 2006

D A TA

SH EET

The system can determine the status of the erase op-

eration by using DQ7, DQ6, DQ2, or RY/BY#. See

“Write Operation Status” for information on these status

bits. When the Embedded Erase algorithm is complete,

the device returns to reading array data and addresses

are no longer latched.

Figure 6 illustrates the algorithm for the erase opera-

tion. See the Erase/Program Operations tables in “AC

Characteristics” for parameters, and to Figure 19 for

timing diagrams.

Sector Erase Command Sequence

Sector erase is a six bus cycle operation. The sector

erase command sequence is initiated by writing two un-

lock cycles, followed by a set-up command. Two addi-

tional unlock write cycles are then followed by the

address of the sector to be erased, and the sector

erase command. Table 4 shows the address and data

requirements for the sector erase command sequence.

The device does not require the system to preprogram

the memory prior to erase. The Embedded Erase algo-

rithm automatically programs and verifies the sector for

an all zero data pattern prior to electrical erase. The

system is not required to provide any controls or tim-

ings during these operations.

After the command sequence is written, a sector erase

time-out of 50 µs begins. During the time-out period,

additional sector addresses and sector erase com-

mands may be written. Loading the sector erase buffer

may be done in any sequence, and the number of sec-

tors may be from one sector to all sectors. The time be-

tween these additional cycles must be less than 50 µs,

otherwise the last address and command might not be

accepted, and erasure may begin. It is recommended

that processor interrupts be disabled during 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 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 ignored. Note that a hardware reset during the

sector erase operation immediately terminates the op-

eration. 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 sta-

tus of the erase operation by using DQ7, DQ6, DQ2, or

RY/BY#. (Refer to “Write Operation Status” for informa-

tion on these status bits.)

Figure 6 illustrates the algorithm for the erase opera-

tion. Refer to the Erase/Program Operations tables in

the “AC Characteristics” section for parameters, and to

Figure 19 for timing diagrams.

Notes:

1. See Table 4 for erase command sequence.

2. See “DQ3: Sector Erase Timer” for more information.

Figure 6.

Erase Operation

Erase Suspend/Erase Resume Commands

The Erase Suspend command allows the system to in-

terrupt a sector erase operation and then read data

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

erasure. The Erase Suspend command has a different

effect depending on whether the Flash device is in

Asynchronous Mode or Burst Mode.

Asynchronous Mode

The Erase Suspend command is only valid when the

Flash device is in Asynchronous Mode. During Erase

Suspend operation Asynchronous read/program oper-

ations behave normally in non-erasing sectors. How-

ever, Erase Suspend operation prevents the Flash

START

Write Erase

Command Sequence

Data Poll

from System

Data = FFh?

Yes

Erasure Completed

Embedded

Erase

algorithm

in progress

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