AM29DL800B datasheet(13/43 Pages) AMD

13 / 43 page

Am29DL800B

P R E L I M I NARY

Table 4.

Am29DL800B Autoselect Codes (High Voltage Method)

Note: L = Logic Low = VIL, H = Logic High = VIH, BA = Bank Address, 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. Sector protection/unprotection can be imple-

mented via two methods.

The primary method requires VID on the RESET# pin

only, and can be implemented either in-system or via

programming equipment. Figure 2 shows the algo-

rithms and Figure 24 shows the timing diagram. This

method uses standard microprocessor bus cycle tim-

ing. For sector unprotect, all unprotected sectors must

first be protected prior to the first sector unprotect write

cycle.

The alternate method intended only for programming

equipment requires VID on address pin A9 and OE#.

This method is compatible with programmer routines

written for earlier 3.0 volt-only AMD flash devices. Pub-

lication number 21467 contains further details; contact

an AMD representative to request a copy.

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 the Autoselect Mode section 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 RE-

SET# pin to VID (11.5 V – 12.5 V). 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 pro-

tected sectors are protected again. Figure 1 shows the

algorithm, and Figure 23 shows the timing diagrams,

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:

Am29DL800B

(Top Boot Block)

Word

VID

XLXL

22h

4Ah

Byte

4Ah

Device ID:

Am29DL800B

(Bottom Boot Block)

Word

VID

XLXL

22h

CBh

Byte

CBh

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.

21519A-5

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