AM29F800B datasheet(11/39 Pages) AMD

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Am29F800B

P R E L I M I NARY

Table 4.

Am29F800B 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 pro-

tected sectors.

Sector protection/unprotection must be implemented

using programming equipment. The procedure re-

quires a high voltage (VID) on address pin A9 and the

control pins. Details on this method are provided in a

supplement, publication number 20374. Contact an

AMD representative to obtain a copy of the appropriate

document.

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.

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 pro-

tected sectors can be programmed or erased by se-

lecting the sector addresses. Once VID is removed

from the RESET# pin, all the previously protected

sectors are protected again. Figure 1 shows the algo-

rithm, and the Temporary Sector Unprotect diagram

shows the timing waveforms, for this feature.

Figure 1.

Temporary Sector Unprotect Operation

Description

Mode

CE#

OE#

WE#

A18

A12

A11

A10

DQ8

DQ15

DQ7

DQ0

Manufacturer ID: AMD

VID

XLXL

01h

Device ID:

Am29F800B

(Top Boot Block)

Word

VID

XLXL

22h

D6h

Byte

D6h

Device ID:

Am29F800B

(Bottom Boot Block)

Word

VID

XLXL

22h

58h

Byte

58h

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.

21504C-5

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