AM29PL320D SPANSION [SPANSION], AM29PL320D Datasheet - Page 20

• Manufacturer Part Number: AM29PL320D
• Description: 32 Megabit (2 M x 16-Bit/1 M x 32-Bit) CMOS 3.0 Volt-only High Performance Page Mode Flash Memory
• Manufacturer: SPANSION [SPANSION]

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 SecSi Sector is a minimum of 128 words
(64 double words) in length, and uses a SecSi Sector
Indicator Bit (DQ7) to indicate whether or not the
SecSi Sector is locked when shipped from the factory.
This bit is permanently 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. Current version of de-
vice has 512 words; future versions will have only
128 words. This should be considered during sys-
tem design.
AMD offers the device with the SecSi Sector either
factory locked or customer lockable. The factory-
locked version is always protected when shipped from
the factory, and has the SecSi (Secured Silicon) Sec-
tor Indicator Bit permanently set to a “1.” The cus-
tomer-lockable version is shipped with the SecSi
Sector unprotected, allowing customers to utilize the
that sector in any manner they choose. The customer-
lockable version has the SecSi (Secured Silicon) Sec-
tor Indicator Bit permanently set to a “0.” Thus, the
SecSi Sector Indicator Bit prevents customer-lockable
devices from being used to replace devices that are
factory locked.
The system accesses the SecSi Sector through a
command sequence (see “Enter SecSi™ Sector/Exit
SecSi Sector Command Sequence”). After the system
has written the Enter SecSi Sector command se-
quence, it may read the SecSi Sector by using the ad-
dresses normally occupied by the boot sectors. This
mode of operation continues until the system issues
the Exit SecSi Sector command sequence, or until
power is removed from the device. On power-up the
device reverts to sending commands to the boot sec-
tors.
Factory Locked: SecSi Sector Programmed and
Protected At the Factory
In a factory locked device, the SecSi Sector is pro-
tected when the device is shipped from the factory.
The SecSi Sector cannot be modified in any way. The
device is available preprogrammed with one of the fol-
lowing:
18
A random, secure ESN only
Customer code through the ExpressFlash service
Both a random, secure ESN and customer code
through the ExpressFlash service.
Am29PL320D
In devices that have an ESN, a Bottom Boot device will
have the 8-word (4-double word) ESN in the lowest ad-
dressable memor y area at addresses 000000h–
000003h in double word mode (or 000000h–000007h
in word mode). In the Top Boot device the starting ad-
dress of the ESN will be at the bottom of the lowest 8
Kbyte boot sector at addresses 1F8000h–1F8003h in
double word mode (or addresses FC0000h–FC0007h
in word 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 SecSi Sector permanently locked.
Contact an AMD representative for details on using
AMD’s ExpressFlash service.
Customer Lockable: SecSi Sector NOT
Programmed or Locked At the Factory
If the security feature is not required, the SecSi Sector
can be treated as an additional Flash memory space,
expanding the size of the available Flash array. Cur-
rent version of device has 512 words; future ver-
sions will have only 128 words. This should be
considered during system design. The SecSi Sec-
tor can be read, programmed, and erased as often as
required. ( In upcoming versions of this device, the
SecSi Sector erase function will not be available. ) Note
that the accelerated programming (ACC) and unlock
bypass functions are not available when programming
the SecSi Sector.
The SecSi Sector can be locked in-system by perform-
ing the following steps:
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.
Write the three-cycle Enter SecSi Sector Region
command sequence.
Write 60h to any address (protect command).
Wait 150 µs, and then write 40h to address 01h (ver-
ify command).
Read from address 02h. The data should be 01h.
Write the reset command (F0h to any address).
Write the four-cycle Exit SecSi Sector command se-
quence to return to reading from the array.
To verify the protect/unprotect status of the SecSi
Sector, follow the algorithm shown in Figure 1.
October 2, 2003