P R E L I M I N A R Y
formerly protected sectors can be programmed or
Write Protect (WP#)
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 24 shows the timing diagrams,
for this feature.
The Write Protect function provides a hardware
method of protecting certain boot sectors without
using VID. This function is one of two provided by the
WP#/ACC pin.
If the system asserts VIL on the WP#/ACC pin, the de-
vice disables program and erase functions in the two
“outermost” 8 Kbyte boot sectors independently of
whether those sectors were protected or unprotected
using the method described in “Sector/Sector Block
Protection and Unprotection”. The two outermost 8
Kbyte boot sectors are the two sectors containing the
lowest addresses in a bottom-boot-configured device,
or the two sectors containing the highest addresses in
a top-boot-configured device.
START
RESET# = VID
(Note 1)
Perform Erase or
Program Operations
If the system asserts VIH on the WP#/ACC pin, the de-
vice reverts to whether the two outermost 8 Kbyte boot
sectors were last set to be protected or unprotected.
That is, sector protection or unprotection for these two
sectors depends on whether they were last protected
or unprotected using the method described in “Sec-
tor/Sector Block Protection and Unprotection”.
RESET# = VIH
Temporary Sector
Unprotect Completed
(Note 2)
Note that the WP#/ACC pin must not be left floating or
unconnected; inconsistent behavior of the device may
result.
Temporary Sector/Sector Block Unprotect
21533C-6
(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 Tables
8 and 9).
Notes:
1. All protected sectors unprotected (If WP#/ACC = VIL,
outermost boot sectors will remain protected).
2. All previously protected sectors are protected once
again.
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 (8.5 V – 12.5 V). During this mode,
Figure 1. Temporary Sector Unprotect Operation
15
Am29DL162C/Am29DL163C
SPANSION [ SPANSION ]
