AM29DL640H datasheet(18/54 Pages) SPANSION

18 / 54 page

Am29DL640H

June 7, 2005

If the system asserts V

IH on the WP#/ACC pin, the de-

vice reverts to whether sectors 0, 1, 140, and 141

were last set to be protected or unprotected. That is,

sector protection or unprotection for these sectors de-

pends on whether they were last protected or unpro-

tected using the method described in “Sector/Sector

Block Protection and Unprotection”.

Note that the WP#/ACC pin must not be left floating or

unconnected; inconsistent behavior of the device may

result.

Table 7.

WP#/ACC Modes

Temporary Sector Unprotect

(Note: For the following discussion, the term “sector”

applies to both sectors and sector blocks. A sector

block consists of two or more adjacent sectors that are

protected or unprotected at the same time (see Table

6).

This feature allows temporary unprotection of previ-

ously protected sectors to change data in-system. The

Temporary Sector Unprotect mode is activated by set-

ting the RESET# pin to V

ID. During this mode, formerly

protected sectors can be programmed or erased by

selecting the sector addresses. Once V

ID is removed

from the RESET# pin, all the previously protected sec-

tors are protected again. Figure 1 shows the algo-

rithm, and Figure 25 shows the timing diagrams, for

this feature. If the WP#/ACC pin is at VIL, sectors 0, 1,

140, and 141 will remain protected during the Tempo-

rary sector Unprotect mode.

Figure 1.

Temporary Sector Unprotect Operation

WP# Input

Voltage

Device

Mode

VIL

Disables programming and erasing in

SA0, SA1, SA140, and SA141

Enables programming and erasing in

SA0, SA1, SA140, and SA141,

dependent on whether they were last

protected or unprotected.

Enables accelerated programming

(ACC). See “Accelerated Program

Operation” on page 9.

START

Perform Erase or

Program Operations

RESET# = V

Temporary Sector

Unprotect Completed

(Note 2)

RESET# = V

(Note 1)

Notes:

1. All protected sectors unprotected (If WP#/ACC = V

IL,

sectors 0, 1, 140, and 141 will remain protected).

2. All previously protected sectors are protected once

again.

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