S29JL032H_09 Datasheet, PDF (26/61 Pages) SPANSION – 32 Megabit (4 M x 8-Bit/2 M x 16-Bit) CMOS 3.0 Volt-only, Simultaneous Read/Write Flash Memory

Data Sheet
8.13
Secured Silicon Sector Flash Memory Region
The Secured Silicon Sector feature provides a Flash memory region that enables permanent part
identification through an Electronic Serial Number (ESN). The Secured Silicon Sector is 256 bytes in length,
and is shipped unprotected, allowing customers to utilize that sector in any manner they choose. The
Secured Silicon Customer Indicator Bit (DQ6) is permanently set to 1 if the part has been customer locked
and is 0 if customer lockable. DQ7, alternatively, is set to 0 if the part has been customer locked, and is 1 if
customer-lockable.
Some current and most future Spansion devices (including future revisions of this device) will offer an option
for programming and permanently locking the Secured Silicon Sector at the factory. DQ7 will become the
Secured Silicon Factory Indicator bit, and as such the Secured Silicon Indicator Bit data will change to 82h for
factory locked, 42h for customer locked, and 02h (no longer 82h) for not factory/customer locked.
The system accesses the Secured Silicon through a command sequence (see Enter Secured Silicon Sector/
Exit Secured Silicon Sector Command Sequence on page 32). After the system has written the Enter
Secured Silicon Sector command sequence, it may read the Secured Silicon Sector by using the addresses
normally occupied by the boot sectors. This mode of operation continues until the system issues the Exit
Secured Silicon Sector command sequence, or until power is removed from the device. On power-up, or
following a hardware reset, the device reverts to sending commands to the first 256 bytes of Sector 0. Note
that the ACC function and unlock bypass modes are not available when the Secured Silicon Sector is
enabled.
8.13.1
Factory Locked: Secured Silicon Sector Programmed and Protected At the
Factory
In a factory locked device, the Secured Silicon Sector is protected when the device is shipped from the
factory. The Secured Silicon Sector cannot be modified in any way. The device is preprogrammed with both a
random number and a secure ESN. The 8-word random number is at addresses 000000h–000007h in word
mode (or 000000h–00000Fh in byte mode). The secure ESN is programmed in the next 8 words at addresses
000008h–00000Fh (or 000010h–00001Fh in byte mode). The device is available preprogrammed with one of
the following:
„ A random, secure ESN only
„ Customer code through Spansion programming services
„ Both a random, secure ESN and customer code through Spansion programming services
Contact an your local sales office for details on using Spansion programming services.
8.13.2
Customer Lockable: Secured Silicon Sector NOT Programmed or Protected
At the Factory
If the security feature is not required, the Secured Silicon Sector can be treated as an additional Flash
memory space. The Secured Silicon Sector can be read any number 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 Secured Silicon Sector.
The Secured Silicon Sector area can be protected using one of the following procedures:
„ Write the three-cycle Enter Secured Silicon Sector Region command sequence, and then follow the in-
system sector protect algorithm as shown in Figure 8.2 on page 25, except that RESET# may be at either
V_IH or V_ID. This allows in-system protection of the Secured Silicon Sector Region without raising any device
pin to a high voltage. Note that this method is only applicable to the Secured Silicon Sector.
„ To verify the protect/unprotect status of the Secured Silicon Sector, follow the algorithm shown in
Figure 8.3 on page 27.
Once the Secured Silicon Sector is locked and verified, the system must write the Exit Secured Silicon Sector
Region command sequence to return to reading and writing the remainder of the array.
The Secured Silicon Sector lock must be used with caution since, once locked, there is no procedure
available for unlocking the Secured Silicon Sector area and none of the bits in the Secured Silicon Sector
memory space can be modified in any way.
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S29JL032H
S29JL032H_00_B8 August 31, 2009