D A T A
S H E E T
vice the ESN will be at addresses
1FF000h–1FF007Fh in word mode (or addresses
3FE000h–3FE0FFh in byte mode).
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.
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 256-byte
Flash memory space, expanding the size of the avail-
able Flash array.
Additionally, note the difference in
the location of the ESN compared to previous
Am29DL32x top boot factory locked devices.
The
Secured Silicon Sector is one-time programmable,
may not be erased, and can be 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 Fig-
RESET# may be at either V
IH
or
V
ID
. This allows in-system protection of the Secured
Silicon Sector without raising any device pin to a
high voltage. Note that this method is only applica-
ble to the Secured Silicon Sector.
■
Write the three-cycle Enter Secured Silicon Sector
Region command sequence, and then use the alter-
nate method of sector protection described in the
section.
The Secured Silicon Sector is one-time programma-
ble. Once the Secured Silicon Sector is locked and
verified, the system must write the Exit Secured Sili-
con Sector Region command sequence to return to
reading and writing the remainder of the array.
The Secured Silicon Sector protection must be used
with caution since, once protected, there is no proce-
dure available for unprotecting the Secured Silicon
Sector area and none of the bits in the Secured Silicon
Sector memory space can be modified in any way.
Secured Silicon Sector
Flash Memory Region
The Secured Silicon Sector feature provides a
256-byte Flash memory region that enables perma-
nent part identification through an Electronic Serial
Number (ESN). The Secured Silicon Sector 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 permanently
set at the factory and cannot be changed, which pre-
vents cloning of a factory locked part. This ensures the
security of the ESN once the product is shipped to the
field.
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 per manently 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 system accesses the Secured Silicon Sector
through a command sequence (see “Enter Secured
Secured Silicon Sector command sequence, it may
read the Secured Silicon Sector by using the ad-
dresses 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 boot sectors.
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 fac-
tory. The Secured Silicon Sector cannot be modified in
any way. The device is available preprogrammed with
one of the following:
■
A random, secure ESN only
■
Customer code through the ExpressFlash service
■
Both a random, secure ESN and customer code
through the ExpressFlash service.
In devices that have an ESN, a Bottom Boot device will
have the 16-byte ESN at addresses
000000h–000007h
in
word
mode
(or
000000h–00000Fh in byte mode). In the Top Boot de-
Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes (refer to Table 14 for com-
mand definitions). In addition, the following hardware
21
December 4, 2006 25686B10
Am29DL32xG
SPANSION [ SPANSION ]
