S29GL032A datasheet(47/95 Pages) SPANSION

47 / 95 page

September 10, 2007 S29GL-A_00_A11

S29GL-A

Data

She e t

7.11

Secured Silicon Sector Flash Memory Region

The Secured Silicon Sector feature provides a Flash memory region that enables permanent part

identification through an Electronic Serial Number (ESN). The Secured Silicon Sector is 256 bytes in length,

and 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 prevents cloning of a factory locked part. This ensures the security of the ESN once the product is

shipped to the field.

The factory offers the device with the Secured Silicon Sector either customer lockable (standard shipping

option) or factory locked (contact a Spansion sales representative for ordering information). The customer-

lockable version is shipped with the Secured Silicon Sector unprotected, allowing customers to program the

sector after receiving the device. The customer-lockable version also contains the Secured Silicon Sector

Indicator Bit permanently set to a 0. The factory-locked version is always protected when shipped from the

factory, and has the Secured Silicon Sector Indicator Bit permanently set to a 1. Thus, the Secured Silicon

Sector Indicator Bit prevents customer-lockable devices from being used to replace devices that are factory

locked. Note that the ACC function and unlock bypass modes are not available when the Secured Silicon

Sector is enabled.

The Secured Silicon sector address space in this device is allocated as follows:

The system accesses the Secured Silicon Sector through a command sequence (see Write Protect (WP#)

on page 48). After the system writes the Enter Secured Silicon Sector command sequence, it may read the

Secured Silicon Sector by using the addresses normally occupied by the first sector (SA0). 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 reverts to sending

commands to sector SA0.

7.11.1

Customer Lockable: Secured Silicon Sector NOT Programmed or Protected

At the Factory

Unless otherwise specified, the device is shipped such that the customer may program and protect the 256-

byte Secured Silicon sector.

The system may program the Secured Silicon Sector using the write-buffer, accelerated and/or unlock

bypass methods, in addition to the standard programming command sequence. See Command Definitions

on page 52.

Programming and protecting the Secured Silicon Sector must be used with caution since, once protected,

there is no procedure 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.

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 Figure 7.2 on page 46, except that RESET# may be at either

VIH or VID. 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 applicable to the Secured Silicon Sector.

Write the three-cycle Enter Secured Silicon Sector Region command sequence, and then use the alternate

method of sector protection described in Sector Group Protection and Unprotection on page 41.

Once the Secured Silicon Sector is programmed, locked and verified, the system must write the Exit Secured

Silicon Sector Region command sequence to return to reading and writing within the remainder of the array.

Secured Silicon Sector

Address Range

Standard Factory

Locked

ExpressFlash

Factory Locked

Customer

Lockable

x16

000000h–000007h

000000h-00000Fh

ESN

ESN or determined

by customer

Determined by

customer

000008h–00007Fh

000010h-0000FFh

Unavailable

Determined by

customer

S29GL032A Datasheet(PDF) 47 Page - SPANSION

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