AM29DL400B datasheet(19/47 Pages) AMD

19 / 47 page

Am29DL400B

Figure 4 illustrates the algorithm for the erase opera-

tion. Refer to the Erase and Program Operations

tables in the AC Characteristics section for parame-

ters, and Figure 18 section for timing diagrams.

Erase Suspend/Erase Resume Commands

The Erase Suspend command, B0h, allows the sys-

tem to interrupt a sector erase operation and then

read data from, or program data to, any sector not

selected for erasure. The bank address is required

when writing this command. This command is valid

only during the sector erase operation, including the

50 µs time-out period during the sector erase com-

mand sequence. The Erase Suspend command is

ignored if written during the chip erase operation or

Embedded Program algorithm.

When the Erase Suspend command is written during

the sector erase operation, the device requires a

maximum of 20 µs to suspend the erase operation.

However, when the Erase Suspend command is writ-

ten during the sector erase time-out, the device

immediately terminates the time-out period and sus-

pends the erase operation.

After the erase operation has been suspended, the

bank enters the erase-suspend-read mode. The sys-

tem can read data from or program data to any

sector not selected for erasure. (The device “erase

suspends” all sectors selected for erasure.) Reading

at any address within erase-suspended sectors pro-

duces status information on DQ7–DQ0. The system

can use DQ7, or DQ6 and DQ2 together, to deter-

mine if a sector is actively erasing or is erase-

suspended. Refer to the Write Operation Status sec-

tion for information on these status bits.

After an erase-suspended program operation is com-

plete, the bank returns to the erase-suspend-read

mode. The system can determine the status of the

program operation using the DQ7 or DQ6 status bits,

just as in the standard Byte Program operation.

Refer to the Write Operation Status section for more

information.

In the erase-suspend-read mode, the system can

also issue the autoselect command sequence. Refer

to the Autoselect Mode and Autoselect Command Se-

quence sections for details.

To resume the sector erase operation, the system

must write the Erase Resume command. The bank

address of the erase-suspended bank is required

when writing this command. Further writes of the

Resume command are ignored. Another Erase Sus-

pend command can be written after the chip has

resumed erasing.

Notes:

1. See Table 5 for erase command sequence.

2. See the section on DQ3 for information on the sector erase timer.

Figure 4. Erase Operation

START

Write Erase

Command Sequence

(Notes 1, 2)

Data Poll to Erasing

Bank from System

Data = FFh?

Yes

Erasure Completed

Embedded

Erase

algorithm

in progress

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