AM29F160DB70EC datasheet(27/47 Pages) SPANSION

27 / 47 page

November 2, 2006 Am29F160D_00_D6

Am29F160D

D A TA SH EE T

toggling, the device successfully completed the

program or erase operation. If it is still toggling, the

device did not complete the operation successfully, and

the system must write the reset command to return to

reading array data.

The remaining scenario is that the system initially de-

termines that the toggle bit is toggling and DQ5 has not

gone high. The system may continue to monitor the

toggle bit and DQ5 through successive read cycles, de-

termining the status as described in the previous para-

graph. Alternatively, it may choose to perform other

system tasks. In this case, the system must start at the

beginning of the algorithm when it returns to determine

the status of the operation (top of Figure 6).

DQ5: Exceeded Timing Limits

DQ5 indicates whether the program or erase time ex-

ceeded 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 exceeds

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 begun. (The sector erase timer does

not apply to the chip erase command.) If additional

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 is always less than 50 µs.

See also the Sector Erase Command Sequence‚ on

page 20 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 accepted

the command sequence, and then read DQ3. If DQ3 is

“1”, the internally controlled erase cycle started; all fur-

ther commands (other than Erase Suspend) are ig-

nored until the erase operation is complete. If DQ3 is

“0”, the device accepts additional sector erase com-

mands. To ensure the command is accepted, the sys-

tem 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 10 on

page 26 shows the outputs for DQ3.

START

Yes

DQ5 = 1?

Yes

Toggle Bit

= Toggle?

Program/Erase

Operation Not

Complete, Write

Reset Command

Program/Erase

Operation Complete

Read DQ7–DQ0

Toggle Bit

= Toggle?

Read DQ7–DQ0

Twice

Read DQ7–DQ0

Notes:

1. Read toggle bit twice to determine whether or not it is

toggling. See text.

2. Recheck toggle bit because it may stop toggling as DQ5

changes to “1”. See text.

Figure 6.

Toggle Bit Algorithm

(Notes

1, 2)

(Note 1)

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