Data
She et
8.17
Persistent Protection Bit Lock (PPB Lock Bit)
A global volatile bit. The PPB Lock Bit is a volatile bit that reflects the state of the Password Protection Mode
Lock Bit after power-up reset. If the Password Protection Mode Lock Bit is also programmed after
programming the Password, the Password Unlock command must be issued to clear and unfreeze the PPB
Lock Bit after a hardware reset (RESET# asserted) or a power-up reset. Successful execution of the
Password Unlock command clears and unfreezes the PPB Lock Bit, allowing for sector PPB bits to be
modified. Without issuing the Password Unlock command, while asserting RESET#, taking the device
through a power-on reset, or issuing the PPB Lock Bit Set command sets the PPB Lock Bit to a the “freeze
state”.
If the Password Protection Mode Lock Bit is not programmed, the device defaults to Persistent Protection
Mode. In the Persistent Protection Mode, the PPB Lock Bit is cleared to the
unfreeze state
after power-up or
hardware reset. The PPB Lock Bit is set to the
freeze state
by issuing the PPB Lock Bit Set command. Once
set to the
freeze state
the only means for clearing the PPB Lock Bit to the “unfreeze state” is by issuing a
hardware or power-up reset. The Password Unlock command is ignored in Persistent Protection Mode.
Reading the PPB Lock Bit requires a 200ns access time.
8.18
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 an AMD 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 has 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.
The Secured Silicon sector address space in this device is allocated as follows:
Secured Silicon Sector
Address Range
000000h–000007h
000008h–00007Fh
ExpressFlash
Factory Locked
ESN or determined by
customer
Determined by customer
Customer Lockable
Determined by customer
ESN Factory Locked
ESN
Unavailable
The system accesses the Secured Silicon Sector through a command sequence (see
After the system has written 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.
November 16, 2007 S29GL-N_01_09
S29GL-N MirrorBit
®
Flash Family
35
SPANSION [ SPANSION ]
