May 11, 2006 S29WS-J_00_A6 S29WS128J/064J 29
Data Sheet
Advanced Sector Protection Software Examples
Ta bl e 7 contains all possible combinations of the DYB, PPB, and PPB Lock Bit relating to the status
of the sector. In summary, if the PPB Lock Bit is locked (set to “0”), no changes to the PPBs are
allowed. The PPB Lock Bit can only be unlocked (reset to “1”) through a hardware reset or power
cycle. See also
Figure 1 for an overview of the Advanced Sector Protection feature.
Hardware Data Protection Methods
The device offers two main types of data protection at the sector level via hardware control:
When WP# is at V
IL
, the four outermost sectors are locked (device specific).
When ACC is at V
IL
, all sectors are locked.
There are additional methods by which intended or accidental erasure of any sectors can be pre-
vented via hardware means. The following subsections describes these methods:
WP# Method
The Write Protect feature provides a hardware method of protecting the four outermost sectors.
This function is provided by the WP# pin and overrides the previously discussed Sector Protec
-
tion/Unprotection method.
If the system asserts V
IL
on the WP# pin, the device disables program and erase functions in the
“outermost” boot sectors. The outermost boot sectors are the sectors containing both the lower
and upper set of sectors in a dual-boot-configured device.
If the system asserts V
IH
on the WP# pin, the device reverts to whether the boot sectors were
last set to be protected or unprotected. That is, sector protection or unprotection for these sectors
depends on whether they were last protected or unprotected.
Note that the WP# pin must not be left floating or unconnected as inconsistent behavior of the
device may result.
The WP# pin must be held stable during a command sequence execution
ACC Method
This method is similar to above, except it protects all sectors. Once ACC input is set to V
IL
, all
program and erase functions are disabled and hence all sectors are protected.
Low V
CC
Write Inhibit
When V
CC
is less than V
LKO
, the device does not accept any write cycles. This protects data during
V
CC
power-up and power-down.
Ta b l e 7 . Sector Protection Schemes
Unique Device PPB Lock Bit
0 = locked
1 = unlocked
Sector PPB
0 = protected
1 = unprotected
Sector DYB
0 = protected
1 = unprotected
Sector Protection Status
Any Sector 0 0 x Protected through PPB
Any Sector 0 0 x Protected through PPB
Any Sector 0 1 1 Unprotected
Any Sector 0 1 0 Protected through DYB
Any Sector 1 0 x Protected through PPB
Any Sector 1 0 x Protected through PPB
Any Sector 1 1 0 Protected through DYB
Any Sector 1 1 1 Unprotected