AM49DL640BH datasheet(21/63 Pages) SPANSION

21 / 63 page

December 5, 2003

Am49DL640BH

ADV ANCE

I N FO RMAT I O N

If the system asserts VIL on the WP#/ACC pin, the de-

vice disables program and erase functions in sectors

0, 1, 140, and 141, independently of whether those

sectors were protected or unprotected using the

method described in “Sector/Sector Block Protection

and Unprotection”.

If the system asserts VIH 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

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 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 Temporary 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

VIH

Enables programming and erasing in

SA0, SA1, SA140, and SA141

VHH

Enables accelerated progamming (ACC).

See “Accelerated Program Operation” on

page 12.

START

Perform Erase or

Program Operations

RESET# = VIH

Temporary Sector

Unprotect Completed

(Note 2)

RESET# = VID

(Note 1)

Notes:

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

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

2. All previously protected sectors are protected once

again.

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