number is at addresses 000000h–000007h in word
mode (or 000000h–00000Fh in byte mode). The se-
cure ESN is programmed in the next 8 words at ad-
dresses 000008h–00000Fh (or 000010h–00001Fh in
byte mode). The device is available preprogrammed
with one of the following:
Secured Silicon Sector
Flash Memory Region
The Secured Silicon Sector feature provides a Flash
memory region that enables permanent part identifica-
tion through an Electronic Serial Number (ESN). The
Secured Silicon Sector is 256 bytes in length, and
uses a Secured Silicon Sector Indicator Bit (DQ7) to
indicate whether or not the Secured Silicon Sector is
locked when shipped from the factory. This bit is per-
manently set at the factory and cannot be changed,
which prevents cloning of a factory locked part. This
ensures the security of the ESN once the product is
shipped to the field.
■ A random, secure ESN only
■ Customer code through the ExpressFlash service
■ Both a random, secure ESN and customer code
through the ExpressFlash service.
Customers may opt to have their code programmed by
AMD through the AMD ExpressFlash service. AMD
programs the customer’s code, with or without the ran-
dom ESN. The devices are then shipped from AMD’s
factory with the Secured Silicon Sector permanently
locked. Contact an AMD representative for details on
using AMD’s ExpressFlash service.
AMD offers the device with the Secured Silicon Sector
either factory locked or customer lockable. The fac-
tory-locked version is always protected when shipped
from the factory, and has the Secured Silicon Sector
Indicator Bit permanently set to a “1.” The cus-
tomer-lockable version is shipped with the Secured
Silicon Sector unprotected, allowing customers to uti-
lize the that sector in any manner they choose. The
customer-lockable version has the Secured Silicon
Sector Indicator Bit permanently set to a “0.” Thus, the
Secured Silicon Sector Indicator Bit prevents cus-
tomer-lockable devices from being used to replace de-
vices that are factory locked. The Secured Silicon
Customer Indicator Bit (DQ6) is permanently set to 1 if
the part has been customer locked, permanently set to
0 if the part has been factory locked, and is 0 if cus-
tomer lockable.
Customer Lockable: Secured Silicon Sector NOT
Programmed or Protected At the Factory
If the security feature is not required, the Secured Sili-
con 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 pro-
gramming (ACC) and unlock bypass functions are not
available when programming the Secured Silicon Sec-
tor.
The Secured Silicon Sector area can be protected
using one of the following procedures:
The system accesses the Secured Silicon Sector Se-
cure through a command sequence (see “Enter Se-
cured Silicon Sector/Exit Secured Silicon Sector
Command Sequence”). 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 re-
verts to sending commands to the first 256 bytes of
Sector 0. Note that the ACC function and unlock by-
pass modes are not available when the Secured Sili-
con Sector is enabled.
■ Write the three-cycle Enter Secured Silicon Sector
Region command sequence, and then follow the
in-system sector protect algorithm as shown in Fig-
ure 2, except that RESET# may be at either VIH or
VID. 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 ap-
plicable to the Secured Silicon Sector.
■ To verify the protect/unprotect status of the Secured
Silicon Sector, follow the algorithm shown in Figure
3.
Once the Secured Silicon Sector is locked and veri-
fied, the system must write the Exit Secured Silicon
Sector Region command sequence to return to read-
ing and writing the remainder of the array.
Factory Locked: Secured Silicon Sector
Programmed and Protected At the Factory
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.
In a factory locked device, the Secured Silicon Sector
is protected when the device is shipped from the fac-
tory. The Secured Silicon Sector cannot be modified in
any way. The device is preprogrammed with both a ran-
dom number and a secure ESN. The 8-word random
18
Am29DL640H
June 7, 2005
SPANSION [ SPANSION ]
