16

Am29F010A

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 pro-

grammed 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 ex-

ceeded 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.” The system may ignore DQ3 if the sys-

tem can guarantee that the time between additional

sector erase commands will always be less than 50

µs.

See also the “Sector Erase Command Sequence”

section.

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

accepted the command sequence, and then read DQ3.

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

begun; all further commands are ignored until the

erase operation is complete. If DQ3 is “0”, the device

will accept additional sector erase commands. To en-

sure 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 com-

mand might not have been accepted. Table 5 shows

the outputs for DQ3.

Table 5.

Write Operation Status

Notes:

1. DQ7 requires a valid address when reading status information. Refer to the appropriate subsection for further details.

2. 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.

Operation

DQ7

(Note 1)

DQ6

DQ5

(Note 2)

DQ3

Standard

Mode

Embedded Program Algorithm

DQ7#

Toggle

0

N/A

Embedded Erase Algorithm

0

Toggle

0

1

Erase

Suspend

Mode

Reading within Erase Suspended Sector

1

No toggle

0

N/A

Reading within Non-Erase Suspended Sector

Data

Data

Data

Data