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Am29LV017B

PREL I M I N AR Y

DQ5: Exceeded Timing Limits

DQ5 indicates whether the program or erase time has

exceeded a specified internal pulse count limit. Under

these conditions DQ5 produces a “1.” This is a failure

condition that indicates the program or erase cycle was

not successfully completed.

The DQ5 failure condition may appear if the system

tries to program a “1” to a location that is previously

programmed to “0.” Only an erase operation can

change a “0” back to a “1.” Under this condition, the

device halts the operation, and when the operation has

exceeded the timing limits, DQ5 produces a “1.”

Under both these conditions, the system must issue

the reset command to return the device to reading

array data.

DQ3: Sector Erase Timer

After writing a sector erase command sequence, the

system may read DQ3 to determine whether or not an

erase operation has begun. (The sector erase timer

does not apply to the chip erase command.) If addi-

tional sectors are selected for erasure, the entire time-

out also applies after each additional sector erase com-

mand. When the time-out is complete, DQ3 switches

from “0” to “1.” If the time between additional sector

erase commands from the system can be assumed to

be less than 50 µs, the system need not monitor DQ3.

See also the “Sector Erase Command Sequence” sec-

tion.

After the sector erase command sequence is written,

the system should read the status on DQ7 (Data# Poll-

ing) or DQ6 (Toggle Bit I) to ensure the device has ac-

cepted the command sequence, and then read DQ3. If

DQ3 is “1”, the internally controlled erase cycle has be-

gun; all further commands (other than Erase Suspend)

are ignored until the erase operation is complete. If

DQ3 is “0”, the device will accept additional sector

erase commands. To ensure the command has been

accepted, the system software should check the status

of DQ3 prior to and following each subsequent sector

erase command. If DQ3 is high on the second status

check, the last command might not have been ac-

cepted. Table 9 shows the outputs for DQ3.

Table 9.

Write Operation Status

Notes:

1. DQ5 switches to ‘1’ when an Embedded Program or Embedded Erase operation has exceeded the maximum timing limits.

See “DQ5: Exceeded Timing Limits” for more information.

2. DQ7 and DQ2 require a valid address when reading status information. Refer to the appropriate subsection for further details.

Operation

DQ7

(Note 2)

DQ6

DQ5

(Note 1)

DQ3

DQ2

(Note 2)

RY/BY#

Standard

Mode

Embedded Program Algorithm

DQ7#

Toggle

0

N/A

No toggle

0

Embedded Erase Algorithm

0

Toggle

0

1

Toggle

0

Erase

Suspend

Mode

Reading within Erase

Suspended Sector

1

No toggle

0

N/A

Toggle

1

Reading within Non-Erase

Suspended Sector

Data

Data

Data

Data

Data

1

Erase-Suspend-Program

DQ7#

Toggle

0

N/A

N/A

0