L320DB12VC datasheet(22/57 Pages) AMD

22 / 57 page

Am29LV320D

December 14, 2005

DA TA SH EET

Secured Silicon Sector Flash Memory

Region

The Secured Silicon sector provides a Flash memory

region that enables permanent par t identification

through an Electronic Serial Number (ESN). The Se-

cured Silicon sector uses a Secured Silicon Indicator

Bit (DQ7) to indicate whether or not the Secured Sili-

con 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

pr oduct is shipped to the field. No te th at th e

Am29LV320D has a Secured Silicon sector size of

64 Kbytes. AMD devices designated as replace-

ments or substitutes, such as the Am29LV320M,

have 256 bytes. This should be considered during

system design.

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 In-

dicator Bit permanently set to a “0.” Thus, the Secured

Silicon Indicator Bit prevents customer-lockable de-

vices from being used to replace devices that are fac-

tory locked.

The system accesses the Secured Silicon sector

through a command sequence (see “Enter Secured

Silicon Sector/ E xit Se cured Silicon Sector

Command Sequence” on page 25). After the system

writes the Enter Secured Silicon sector command se-

quence, 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 com-

mand 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 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

has the 16-byte (8-word) ESN in sector 0 at addresses

00000h–0000Fh in byte mode (or 00000h–00007h in

word mode). In the Top Boot device the ESN is in sec-

tor 63 at addresses 3F0000h–3F000Fh in byte mode

(or 1F8000h–1F8007h in word mode). Note that in up-

coming top boot versions of this device, the ESN is lo-

cated in sector 70 at addresses 3FE000h–3FE00Fh in

byte mode (or 1FF000h–1FF007h 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 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

The customer lockable version allows the Secured Sil-

icon Sector to be programmed once and then perma-

nently locked after it ships from AMD. Note that the

Am29LV320D has a Secured Silicon Sector size of

64 Kbytes. AMD devices designated as replace-

ments or substitutes, such as the Am29LV320M,

have 256 bytes. This should be considered during

system design. Additionally, note the change in

the location of the ESN in upcoming top boot fac-

tory locked devices. 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 the following procedures:

■ Write the three-cycle Enter Secured Silicon Sector

command sequence, and then follow the in-system

sector protect algorithm as shown in Figure 2, on

page 19, except that RESET# may be at either VIH

or V

ID. This allows in-system protection of the Se-

cured Silicon Sector 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, on page 21.

Once the Secured Silicon Sector is locked and veri-

fied, the system must write the Exit Secured Silicon

Sector 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.

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