AM29LV004 datasheet(10/36 Pages) AMD

10 / 36 page

Am29LV004

PR EL I M I NAR Y

Table 4.

Am29LV004 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 hard-

ware sector unprotection feature re-enables both pro-

gram and erase operations in previously protected

sectors.

The device is shipped with all sectors unprotected.

AMD offers the option of programming and protecting

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 protected

or unprotected. See “Autoselect Mode” for details.

Sector protection/unprotection must be implemented

using programming equipment.The procedure requires

a high voltage (VID) on address pin A9 and OE#. De-

tails on this method are provided in a supplement, pub-

lication number 20874. Contact an AMD representative

to request a copy.

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 RE-

SET# 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 RE-

SET# pin, all the previously protected sectors are

protected again. Figure 1 shows the algorithm, and

Figure 19 shows the timing diagrams, for this feature.

Description

CE#

OE#

WE#

A18

A13

A12

A10

DQ7

DQ0

Manufacturer ID: AMD

VID

XLXL

01h

Device ID: Am29LV004T

(Top Boot Block)

VID

XLXL

B5h

Device ID: Am29LV004B

(Bottom Boot Block)

VID

XLXL

B6h

Sector Protection Verification

VID

XLX

01h

(protected)

00h

(unprotected)

START

Perform Erase or

Program Operations

RESET# = VIH

Temporary Sector

Unprotect Completed

(Note 2)

RESET# = VID

(Note 1)

Notes:

1. All protected sectors unprotected.

2. All previously protected sectors are protected once

again.

Figure 1.

Temporary Sector Unprotect Operation

21522A-4

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