s71ws256jc0 Meet Spansion Inc., s71ws256jc0 Datasheet - Page 46

• Manufacturer Part Number: s71ws256jc0
• Description: Stacked Multi-chip Product Mcp 128/64 Megabit 8m/4m X 16-bit Cmos 1.8 Volt-only, Simultaneous Read/write, Burst Mode Flash Memory With Cellularram
• Manufacturer: Meet Spansion Inc.

12.6
12.7
44
Advanced Sector Protection Software Examples
Hardware Data Protection Methods
Table 12.2
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
The device offers two main types of data protection at the sector level via hardware control:
! When WP# is at V
! When ACC is at V
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
“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
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
program and erase functions are disabled and hence all sectors are protected.
Low V
When V
V
CC
power-up and power-down.
Unique Device PPB Lock Bit
CC
CC
Any Sector
Any Sector
Any Sector
Any Sector
Any Sector
Any Sector
Any Sector
Any Sector
is less than V
Write Inhibit
contains all possible combinations of the DYB, PPB, and PPB Lock Bit relating to the
1 = unlocked
0 = locked
IL
IL
Figure 12.1
, all sectors are locked.
IL
, the four outermost sectors are locked (device specific).
LKO
IH
on the WP# pin, the device disables program and erase functions in the
on the WP# pin, the device reverts to whether the boot sectors were
, the device does not accept any write cycles. This protects data during
Table 12.2 Sector Protection Schemes
0
0
0
0
1
1
1
1
S29WS128J/064J
for an overview of the Advanced Sector Protection feature.
1 = unprotected
D a t a
0 = protected
Sector PPB
0
0
1
1
0
0
1
1
S h e e t
1 = unprotected
0 = protected
Sector DYB
x
x
1
0
x
x
0
1
Sector Protection Status
Protected through DYB
Protected through DYB
Protected through PPB
Protected through PPB
Protected through PPB
Protected through PPB
S29WS-J_M0_A4 June 24, 2005
Unprotected
Unprotected
IL
, all