AM29LV001BB-70JC Просмотр технического описания (PDF) - Advanced Micro Devices

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AM29LV001BB-70JC

1 Megabit (128 K x 8-Bit) CMOS 3.0 Volt-only Boot Sector Flash Memory

Advanced Micro Devices 

Figure 3 illustrates the algorithm for the program oper-

ation. See the Erase/Program Operations table in “AC

Characteristics” for parameters, and to Figure 15 for

timing diagrams.

START

Write Program

Command Sequence

Embedded

Program

algorithm

in progress

Data Poll

from System

Verify Data?

No

Yes

Increment Address

No

Last Address?

Yes

Programming

Completed

Note:

See Table 5 for program command sequence.

Figure 3. Program Operation

Chip Erase Command Sequence

Chip erase is a six bus cycle operation. The chip erase

command sequence is initiated by writing two unlock

cycles, followed by a set-up command. Two additional

unlock write cycles are then followed by the chip erase

command, which in turn invokes the Embedded Erase

algorithm. The device does not require the system to

preprogram prior to erase. The Embedded Erase algo-

rithm automatically preprograms and verifies the entire

memory for an all zero data pattern prior to electrical

erase. The system is not required to provide any con-

trols or timings during these operations. Table 5 shows

the address and data requirements for the chip erase

command sequence.

Any commands written to the chip during the

Embedded Erase algorithm are ignored. Note that a

hardware reset during the chip erase operation imme-

diately terminates the operation. The Chip Erase

command sequence should be reinitiated once the

device has returned to reading array data, to ensure

data integrity.

The system can determine the status of the erase oper-

ation by using DQ7, DQ6, or DQ2. 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 4 illustrates the algorithm for the erase opera-

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

Characteristics” for parameters, and to Figure 16 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

unlock cycles, followed by a set-up command. Two

additional unlock write cycles are then followed by the

address of the sector to be erased, and the sector

erase command. Table 5 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

timings 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

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

between 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 recom-

mended 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

September 26, 2002

Am29LV001B

15

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