August 12, 2004 S29PL127J_064J_032J_MCP_00_A3
S29PL127J/S29PL064J/S29PL032J for MCP
37
P r e l i m i n a r y
Temporary Sector Unprotect
This feature allows temporary unprotection of previously protected sectors to
change data in-system. The Sector Unprotect mode is activated by setting the
RESET# pin to V
ID
. During this mode, formerly protected sectors can be pro-
grammed or erased by selecting the sector addresses. Once V
ID
is removed from
the RESET# pin, all the previously protected sectors are protected again. 2 shows
the algorithm, and 21 shows the timing diagrams, for this feature. While PPB lock
is set, the device cannot enter the Temporary Sector Unprotection Mode.
SecSi (Secured Silicon) Sector Flash Memory Region
The SecSi (Secured Silicon) Sector feature provides a Flash memory region that
enables permanent part identification through an Electronic Serial Number (ESN)
The 128-word SecSi sector is divided into 64 factory-lockable words that can be
programmed and locked by the customer. The SecSi sector is located at ad-
dresses 000000h-00007Fh in both Persistent Protection mode and Password
Protection mode. It uses indicator bits (DQ6, DQ7) to indicate the factory-locked
and customer-locked status of the part.
The system accesses the SecSi Sector through a command sequence (see the
Enter SecSi Sector/Exit SecSi Sector Command Sequence). After the system
has written the Enter SecSi Sector command sequence, it may read the SecSi
Sector by using the addresses normally occupied by the boot sectors. This mode
of operation continues until the system issues the Exit SecSi Sector command se-
quence, or until power is removed from the device. On power-up, or following a
hardware reset, the device reverts to sending commands to the normal address
space.
Note that the ACC function and unlock bypass modes are not available
when the SecSi Sector is enabled.
Factory-Locked Area (64 words)
The factory-locked area of the SecSi Sector (000000h-00003Fh) is locked when
the part is shipped, whether or not the area was programmed at the factory. The
Notes:
1. All protected sectors unprotected (If WP#/ACC = V
IL
, upper two and lower two
sectors will remain protected).
2. All previously protected sectors are protected once again
Figure 2. Temporary Sector Unprotect Operation
START
Perform Erase or
Program Operations
RESET# = V
IH
Temporary Sector
Unprotect Completed
(Note 2)
RESET# = V
ID
(Note 1)