AM29DL322D datasheet(21/56 Pages) AMD

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Am29DL322D/323D/324D

December 13, 2005

SecSi

TM (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 uses a SecSi Sector Indica-

tor 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 64 Kbytes; future versions will have only

256 bytes. This should be considered during sys-

tem design.

AMD offers the device with the SecSi Sector either

fa cto r y locked or c u stomer lock able. The fa c-

tory-locked version is always protected when shipped

from the factory, and has the SecSi (Secured Silicon)

Sector 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 cus-

tomer-lockable version has the SecSi (Secured

Silicon) Sector Indicator Bit permanently set to a “0.”

Thus, the SecSi Sector Indicator Bit prevents cus-

tomer-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

TM 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

addresses 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, or

following a hardware reset, the device reverts to send-

ing commands to the boot sectors.

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

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 ha v e the 16-b y te ESN at addresses

000000h–0 00007h

w o rd

mode

(or

000000h–00000Fh in byte mode). In the Top Boot de-

vice the ESN will be at addresses 1F8000h–1F8007h

in word mode (or addresses 3F0000h–3F000Fh in

byte mode). Note that in upcoming top boot versions

of this device, the ESN will be located at addresses

1FF000h–1FF007h in word mode (or addresses

3FE000h–3FE00Fh 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 SecSi Sector permanently locked.

Contact an AMD representative for details on using

AMD’s ExpressFlash service.

Customer Lockable: SecSi Sector NOT

Programmed or Protected 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 64 Kbytes; future

versions will have only 256 bytes. This should be

considered during system design. Additionally,

note the change in the location of the ESN in up-

coming top boot factory locked devices. The SecSi

Sector can be read, programmed, and erased as often

as required. (Note that 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 area can be protected using one of

the following procedures:

■ Write the three-cycle Enter SecSi Sector Region

command sequence, and then follow the in-system

sector protect algorithm as shown in Figure 2, ex-

cept that RESET# may be at either VIH or VID. This

allows in-system protection of the SecSi Sector

without raising any device pin to a high voltage.

Note that this method is only applicable to the SecSi

Sector

■ Write the three-cycle Enter SecSi Sector Region

command sequence, and then use the alternate

method of sector protection described in the “Sec-

tor/Sector Block Protection and Unprotection” sec-

tion.

Once the SecSi Sector is locked and verified, the sys-

te m mu s t wr ite the Exit S e cSi Sector Region

command sequence to return to reading and writing

the remainder of the array.

The SecSi Sector protection must be used with cau-

tion since, once protected, there is no procedure

available for unprotecting the SecSi Sector area and

none of the bits in the SecSi Sector memory space

can be modified in any way.

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