AM29F160DB75EC datasheet(15/47 Pages) SPANSION

15 / 47 page

November 2, 2006 Am29F160D_00_D6

Am29F160D

D A TA SH EE T

Write Protect (WP#)

The Write Protect function provides a hardware

method of protecting the 16 Kbyte boot sector from

erasure without using VID.

If the system asserts VIL on the WP# pin, the device

disables erase functions for the 16 Kbyte boot sector

(SA34 for top boot device and SA0 for bottom boot de-

vice) independently of whether those sectors were

protected or unprotected using the method described

in Sector Protection/Unprotection‚ on page 12.

If the system asserts VIH on the WP# pin, the device

reverts to whether the 16 Kbyte boot sector was previ-

ously set to be protected or unprotected using the

method described in Sector Protection/Unprotection‚

on page 12.

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. During this mode, formerly protected

sectors can be programmed or erased by selecting the

sector addresses. However, note that the boot sector is

still protected from erasure only if WP# is asserted low.

Once VID is removed from the RESET# pin, all the pre-

viously protected sectors are protected again. Figure 2,

on page 14 shows the algorithm, and Figure 19, on

page 38 shows the timing diagrams, for this feature.

Figure 1.

Temporary Sector Unprotect Operation

START

Perform Erase or

Program Operations

RESET# = VIH

Temporary Sector

Unprotect Completed

(Note 2)

RESET# = VID

(Note 1)

Notes:

1. All protected sectors unprotected. However, boot sector

remains protected from erasure only if WP# is low.

2. All previously protected sectors are protected once

again.

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