TMS29LF040, TMS29VF040

524288 BY 8-BIT

FLASH MEMORIES

SMJS825D – SEPTEMBER 1995 – REVISED JUNE 1998

9

POST OFFICE BOX 1443

erase-suspend command

The erase-suspend command (B0h) allows interruption of a sector-erase operation to read data from unaltered

erase-suspend command (B0h) is latched on the rising edge of W. Once the sector-erase operation is in

progress, the erase-suspend command requests the internal write-state machine to halt operation at

predetermined breakpoints. The erase-suspend command is valid only during the sector-erase operation and

is invalid during the byte-programming and chip-erase operations. The sector-erase delay timer expires

immediately if the erase-suspend command is issued while the delay is active.

After the erase-suspend command is issued, the device typically takes between 0.1

µs and 15 µs to suspend

the operation. The toggle bit must be monitored to determine when the suspend has been executed. When the

toggle bit stops toggling, data can be read from sectors that are not selected for erase. Reading from a sector

selected for erase can result in invalid data. See the operation status section for a full description.

Once the sector-erase operation is suspended, further writes of the erase-suspend command are ignored. The

erase-resume command (30h) causes the device to restart the suspended sector operation. To erase additional

sectors, reissue the six-cycle sector-erase command sequence. Any other command sequence written while

in suspend mode causes the device to reset to the read mode.

erase-resume command

The erase-resume command (30h) restarts a suspended sector-erase operation from where it was halted to

command (30h) is latched on the rising edge of W. When an erase-suspend/erase-resume command

combination is written, the internal pulse counter is reset to zero and the exceed-timing-limit indicator (DQ5)

is set to logic-low. The erase-resume command is valid only in the erase-suspend state. After the erase-resume

command is executed, the device returns to the valid sector-erase state and further writes of the erase-resume

command are ignored. After the device has resumed the sector-erase operation, another erase-suspend

command can be issued to the device.

operation status

status-bit definitions

During operation of the embedded program and erase functions, the status of the device can be determined

by reading the data state of designated outputs. The data-polling bit (DQ7) and toggle bit (DQ6) require multiple

successive reads to observe a change in the state of the designated output. Table 4 defines the values of the

status flags.

Device Operation‡

DQ7

DQ6

DQ5

DQ4

DQ3

DQ2

DQ1

DQ0

Byte-programming in progress

DQ7

T

0

X

0

X

X

X

Byte-programming exceed time limit

DQ7

T

1

X

0

X

X

X

Byte-programming complete

D

D

D

D

D

D

D

D

Sector- / chip-erase in progress

0

T

0

X

1

X

X

X

Sector- / chip-erase exceed time limit

0

T

1

X

1

X

X

X

Sector- / chip-erase complete

1

1

1

1

1

1

1

1

† T= toggle, D = data, X = data undefined, DQ7 = complement of data written to DQ7

‡ DQ4, DQ2, DQ1, and DQ0 are reserved for future use.