AM29DL16XD datasheet(21/57 Pages) AMD

21 / 57 page

December 1, 2006 21533E5

Am29DL16xD

D A TA

SH EET

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 uses an Indicator Bit (DQ7) to

indicate whether or not the 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 secu-

rity of the ESN once the product is shipped to the field.

Current version of device has 64 Kbytes; future

versions will have only 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-loc k ab le v e rsio n is s h ipped with the

unprotected, allowing customers to utilize the that sec-

tor 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 customer-lockable de-

vices from being used to replace devices that are

factory locked.

The system accesses the Secured Silicon Sector

through a command sequence (see “Enter Secured

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 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 in the lowest addressable mem-

ory area at addresses 00000h–00007h in word mode

(or 000000h–00000Fh in byte mode). In the Top Boot

device the starting address of the ESN will be at the

bottom of the lowest 8 Kbyte boot sector at addresses

F8000h–F8007h in word mode (or 1F0000h–1F000Fh

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 Flash

memory space, expanding the size of the available

Flash array. Current version of device has 64

Kbytes; future versions will have only 256 bytes.

This should be considered during system design.

The Secured Silicon Sector can be read, programmed,

and erased as often as required. (Note that in upcoming

versions of this device, the Secured Silicon Sector

erase function will not be available.) Note that the ac-

celerated programming (ACC) and unlock bypass

functions are not available when programming the Se-

cured 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-

ure 2, except that RESET# may be at either V

IH or

ID. This allows in-system protection of the without

raising any device pin to a high voltage. Note that

this method is only applicable 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

“Sector/Sector Block Protection and Unprotection”.

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.

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.

Hardware Data Protection

The command sequence requirement of unlock cycles

for programming or erasing provides data protection

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