AM29LV640ML101PCI datasheet(20/62 Pages) SPANSION

20 / 62 page

Am29LV640MH/L

December 14, 2005

DA TA SH EET

Write Protect (WP#)

The Write Protect function provides a hardware

method of protecting the first or last sector without

using V

ID. Write Protect is one of two functions pro-

vided by the WP#/ACC input.

If the system asserts V

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

vice disables program and erase functions in the first

or last sector independently of whether those sectors

were protected or unprotected using the method de-

scribed in “Sector Group Protection and Unprotection”.

Note that if WP#/ACC is at V

IL when the device is in

the standby mode, the maximum input load current is

increased. See the table in “DC Characteristics”.

If the system asserts V

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

vice reverts to whether the first or last sector was pre-

viously set to be protected or unprotected using the

method described in “Sector Group Protection and

Unprotection”. Note: No external pullup is necessary

since the WP#/ACC pin has internal pullup to V

CC.

Temporary Sector Group Unprotect

(Note: In this device, a sector group consists of four ad-

jacent sectors that are protected or unprotected at the

same time (see Table 4).

This feature allows temporary unprotection of previ-

ously protected sector groups to change data in-sys-

tem. The Sector Group Unprotect mode is activated by

setting the RESET# pin to VID. During this mode, for-

merly protected sector groups can be programmed or

erased by selecting the sector group addresses. Once

VID is removed from the RESET# pin, all the previously

protected sector groups are protected again. Figure 1

shows the algorithm, and Figure 23 shows the timing

diagrams, for this feature.

Notes:

1. All protected sector groups unprotected (If WP# = V

IL, the first or last sector will remain protected).

2. All previously protected sector groups are protected once again.

Figure 1.

Temporary Sector Group Unprotect Operation

START

Perform Erase or

Program Operations

RESET# = V

Temporary Sector

Group Unprotect

Completed (Note 2)

RESET# = V

(Note 1)

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