AM29LV640MH datasheet(27/62 Pages) AMD

27 / 62 page

December 14, 2005

Am29LV640MH/L

DA TA SH EET

The Read-Only Operations table provides the read pa-

rameters, and Figure 14 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).

Note that if DQ1 goes high during a Write Buffer Pro-

gramming operation, the system must write the

Write-to-Buffer-Abort Reset command sequence to

reset the device for the next operation.

Autoselect Command Sequence

The autoselect command sequence allows the host

system to read several identifier codes at specific ad-

dresses:

Note: The device ID is read over three cycles. SA = Sector Address

Tables 10 and 11 show the address requirements and

codes. This method is an alternative to that shown in

Table 3, which is intended for PROM programmers

and requires V

ID on address pin A9. The autoselect

command sequence may be written to an address that

is either in the read or erase-suspend-read mode. The

autoselect command may not be written while the de-

vice is actively programming 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:

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/16-byte random Electronic Serial

Number (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 is-

sues the four-cycle Exit SecSi Sector command se-

quence. The Exit SecSi Sector command sequence

returns the device to normal operation. Tables 10 and

11 show the address and data requirements for both

command sequences. See also “SecSi (Secured Sili-

con) Sector Flash Memory Region” for further informa-

tion. Note that the ACC function and unlock bypass

modes are not available when the SecSi Sector is en-

abled.

Word/Byte 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. Tables 10 and 11 show the

address and data requirements for the word/byte pro-

gram command sequence, respectively.

Identifier Code

A7:A0

(x16)

A6:A-1

(x8)

Manufacturer ID

00h

Device ID, Cycle 1

01h

02h

Device ID, Cycle 2

0Eh

1Ch

Device ID, Cycle 3

0Fh

1Eh

SecSi Sector Factory Protect

03h

06h

Sector Protect Verify

(SA)02h

(SA)04h

AM29LV640MH Datasheet(PDF) 27 Page - Advanced Micro Devices

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