M29F002 データシートの表示（PDF） - Advanced Micro Devices

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M29F002

2 Megabit (256 K x 8-Bit) CMOS 5.0 Volt-only Boot Sector Flash Memory

Advanced Micro Devices 

PRELIMINARY

Any commands written to the device during the Em-

bedded Program Algorithm are ignored. On the

Am29F002 only, 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.

Programming is allowed in any sequence and across

sector boundaries. A bit cannot be programmed

from a “0” back to a “1”. Attempting to do so may halt

the operation and set DQ5 to “1”, or cause the Data#

Polling algorithm to indicate the operation was suc-

cessful. However, a succeeding read will show that the

data is still “0”. Only erase operations can convert a “0”

to a “1”.

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

20818C-5

Note: See the appropriate Command Definitions table for

program command sequence.

Figure 2. 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. The Command

Definitions table shows the address and data require-

ments for the chip erase command sequence.

Any commands written to the chip during the Embed-

ded Erase algorithm are ignored. On the Am29F002

only, note that a hardware reset during the sector

erase operation immediately terminates the operation.

The Sector Erase command sequence should be rein-

itiated once the device has returned to reading array

data, to ensure data integrity.

The system can determine the status of the erase

operation by using DQ7, DQ6, or DQ2. See “Write

Operation Status” for information on these status

bits. When the Embedded Erase algorithm is com-

plete, the device returns to reading array data and

addresses are no longer latched.

Figure 3 illustrates the algorithm for the erase opera-

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

Characteristics” for parameters, and to the Chip/Sector

Erase Operation Timings for timing waveforms.

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. The Command Definitions table

shows the address and data requirements for the sec-

tor 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

12

Am29F002/Am29F002N

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