AM29SL400C datasheet(14/44 Pages) SPANSION

14 / 44 page

March 3, 2005

Ad vance

Inform ati o n

priate highest order address bits (see Table 2 on

page 11 and Table 3 on page 11). Table 4 shows the

remaining address bits that are don’t care. When all

necessary bits have been set as required, the pro-

gramming equipment may then read the corre-

sponding identifier code on DQ7–DQ0.

To access the autoselect codes in-system, the host

system can issue the autoselect command via the

command register, as shown in Table 5 on page 18.

This method does not require VID. See Command

Definitions‚ on page 18 for details on using the au-

toselect mode.

Table 4. Am29SL400C Autoselect Codes (High Voltage Method)

L = Logic Low = VIL, H = Logic High = VIH, SA = Sector Address, X = Don’t care.

Sector Protection/Unprotection

The hardware sector protection feature disables both

program and erase operations in any sector. The

hardware sector unprotection feature re-enables

both program and erase operations in previously

protected sectors. Sector protection/unprotection

can be implemented via two methods.

Sector protection/unprotection requires VID on the

RESET# pin only, and can be implemented either

in-system or via programming equipment. Figure 2‚

on page 14 shows the algorithms and Figure 24‚ on

page 37 shows the timing diagram. This method

uses standard microprocessor bus cycle timing. For

sector unprotect, all unprotected sectors must first

be protected prior to the first sector unprotect write

cycle.

The device is shipped with all sectors unprotected.

AMD offers the option of programming and protect-

ing sectors at its factory prior to shipping the device

through AMD’s ExpressFlash™ Service. Contact an

AMD representative for details.

It is possible to determine whether a sector is pro-

tected or unprotected. See Autoselect Mode‚ on

page 11 for details.

Temporary Sector Unprotect

This feature allows temporary unprotection of previ-

ously protected sectors to change data in-system.

The Sector Unprotect mode is activated by setting

the RESET# pin to VID. During this mode, formerly

protected sectors can be programmed or erased by

selecting the sector addresses. Once VID is removed

from the RESET# pin, all the previously protected

sectors are protected again. Figure 3‚ on page 16

shows the algorithm, and Figure 22 shows the timing

diagrams, for this feature.

Description

Mode

CE#

OE# WE#

A17

A12

A11

A10

DQ8

DQ15

DQ7

DQ0

Manufacturer ID: AMD

VID

01h

Device ID:

Am29SL400C

(Top Boot Block)

Word

VID

22h

70h

Byte

70h

Device ID:

Am29SL400C

(Bottom Boot

Block)

Word

VID

22h

F1h

Byte

F1h

Sector Protection

Verification

VID

01h

(protected)

00h

(unprotected

)

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