38
S29PL127J/S29PL064J/S29PL032J for MCP
S29PL127J_064J_032J_MCP_00_A3 August 12, 2004
P r e l i m i n a r y
SecSi Sector Factory-locked Indicator Bit (DQ7) is permanently set to a “1”. Op-
tional Spansion programming services can program the factory-locked area with
a random ESN, a customer-defined code, or any combination of the two. Because
only Spansion can program and protect the factory-locked area, this method en-
sures the security of the ESN once the product is shipped to the field. Contact
your local sales office for details on using Spansion’s programming services. Note
that the ACC function and unlock bypass modes are not available when the SecSi
sector is enabled.
Customer-Lockable Area (64 words)
The customer-lockable area of the SecSi Sector (000040h-00007Fh) is shipped
unprotected, which allows the customer to program and optionally lock the area
as appropriate for the application. The SecSi Sector Customer-locked Indicator
Bit (DQ6) is shipped as “0” and can be permanently locked to “1” by issuing the
SecSi Protection Bit Program Command. The SecSi Sector can be read any num-
ber of times, but can be programmed and locked only once. Note that the
accelerated programming (ACC) and unlock bypass functions are not available
when programming the SecSi Sector.
The Customer-lockable SecSi Sector area can be protected using one of the
following procedures:
Write the three-cycle Enter SecSi Sector Region command sequence, and
then follow the in-system sector protect algorithm as shown in
Figure 1
, ex-
cept that
RESET# may be at either V
IH
or V
ID
. This allows in-system protec-
tion of the SecSi Sector Region without raising any device pin to a high
voltage. Note that this method is only applicable to the SecSi Sector.
To verify the protect/unprotect status of the SecSi Sector, follow the algo-
rithm shown in
Figure 3
.
Once the SecSi Sector is locked and verified, the system must write the Exit SecSi
Sector Region command sequence to return to reading and writing the remainder
of the array.
The SecSi Sector lock must be used with caution since, once locked, there is no
procedure available for unlocking the SecSi Sector area and none of the bits in
the SecSi Sector memory space can be modified in any way.
SecSi Sector Protection Bits
The SecSi Sector Protection Bits prevent programming of the SecSi Sector mem-
ory area. Once set, the SecSi Sector memory area contents are non-modifiable.