L640DU21NF datasheet(26/57 Pages) AMD

26 / 57 page

Am29LV640D/Am29LV641D

22366C6 January 22, 2007

D A TA

SH EET

The system must issue the reset command to return

the device to the read (or erase-suspend-read) mode if

DQ5 goes high during an active program or erase op-

eration, or if the device is in the autoselect mode. See

the next section, Reset Command, for more informa-

tion.

See also “Requirements for Reading Array Data” on

page 10 in the Device Bus Operations section for

more information. The “Read-Only Operations” on

page 37 table provides the read parameters, and Fig-

ure 13, on page 37 shows the timing diagram.

Reset Command

Writing the reset command resets the device to the

read or erase-suspend-read mode. Address bits are

don’t cares for this command.

The reset command may be written between the se-

quence cycles in an erase command sequence before

erasing begins. This resets the device to the read

mode. Once erasure begins, however, the device ig-

nores reset commands until the operation is complete.

The reset command may be written between the

sequence cycles in a program command sequence

before programming begins. This resets the device to

the read mode. If the program command sequence is

written while the device is in the Erase Suspend mode,

writing the reset command returns the device to the

erase-suspend-read mode. Once programming be-

gins, however, the device ignores reset commands

until the operation is complete.

The reset command may be written between the se-

quence cycles in an autoselect command sequence.

Once in the autoselect mode, the reset command

must be written to return to the read mode. If the de-

vice entered the autoselect mode while in the Erase

Suspend mode, writing the reset command returns the

device to the erase-suspend-read mode.

If DQ5 goes high during a program or erase operation,

writing the reset command returns the device to the

read mode (or erase-suspend-read mode if the device

was in Erase Suspend).

Autoselect Command Sequence

The autoselect command sequence allows the host

system to access the manufacturer and device codes,

and determine whether or not a sector is protected.

Table 10 on page 28 shows the address and data re-

quirements. This method is an alternative to that

shown in Table 3 on page 16, which is intended for

PROM programmers and requires V

ID on address pin

A9. The autoselect command sequence may be writ-

ten to an a dd ress th at is eith er in th e rea d or

erase-suspend-read mode. The autoselect command

cannot be written while the device is actively program-

ming or erasing.

The autoselect command sequence is initiated by first

writing two unlock cycles. This is followed by a third

write cycle that contains the autoselect command. The

device then enters the autoselect mode. The system

may read at any address any number of times without

initiating another autoselect command sequence:

■ A read cycle at address XX00h returns the manu-

facturer code.

■ A read cycle at address XX01h returns the device

code.

■ A read cycle to an address containing a sector

group address (SA), and the address 02h on A7–A0

returns 01h if the sector group is protected, or 00h

if it is unprotected. (Refer to Table 4 on page 17 for

valid sector addresses).

The system must write the reset command to return to

the read mode (or erase-suspend-read mode if the de-

vice was previously in Erase Suspend).

Enter SecSi Sector/Exit SecSi Sector

Command Sequence

The SecSi Sector region provides a secured data area

containing an 8-word random Electronic Serial Num-

ber (ESN). The system can access the SecSi Sector

region by issuing the three-cycle Enter SecSi Sector

command sequence. The device continues to access

the SecSi Sector region until the system issues the

four-cycle Exit SecSi Sector command sequence. The

Exit SecSi Sector command sequence returns the de-

vice to normal operation. Table 10 on page 28 shows

the address and data requirements for both command

sequences. See also “SecSi (Secured Silicon) Sector

Flash Memory Region” on page 20 for further informa-

tion.

Word Program Command Sequence

Programming is a four-bus-cycle operation. The pro-

gram command sequence is initiated by writing two

unlock write cycles, followed by the program set-up

command. The program address and data are written

next, which in turn initiate the Embedded Program al-

gorithm. The system is not required to provide further

controls or timings. The device automatically provides

internally generated program pulses and verifies the

programmed cell margin. The “Command Definitions”

on page 28 shows the address and data requirements

for the word program command sequence.

When the Embedded Program algorithm is complete,

the device returns to the read mode and addresses

are no longer latched. The system determines the sta-

tus of the program operation by using DQ7, DQ6, or

RY/BY#. Refer to “Write Operation Status” on page 29

for information on these status bits.

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