May 13, 2004 27631A4 S29GLxxxN MirrorBitTM Flash Family 51
Advance Information
Lock Bit, there will be no way to clear and unfreeze the PPB Lock Bit. The Pass-
word Protection Mode Lock Bit, once programmed, prevents reading the 64-bit
password on the DQ bus and further password programming. The Password Pro-
tection Mode Lock Bit is not erasable. Once Password Protection Mode Lock Bit is
programmed, the Persistent Protection Mode Lock Bit is disabled from program-
ming, guaranteeing that no changes to the protection scheme are allowed.
64-bit Password
The 64-bit Password is located in its own memory space and is accessible through
the use of the Password Program and Password Read commands. The password
function works in conjunction with the Password Protection Mode Lock Bit, which
when programmed, prevents the Password Read command from reading the con-
tents of the password on the pins of the device.
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 Protec-
tion 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 exe-
cution 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 com-
mand is ignored in Persistent Protection Mode.
Reading the PPB Lock Bit requires a 200ns access time.
SecSi (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 is 256 bytes in length, and uses a SecSi Sector Indicator
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.
The factory offers the device with the SecSi Sector either customer lockable
(standard shipping option) or factory locked (contact an AMD sales representa-
tive for ordering information). The customer-lockable version is shipped with the
SecSi Sector unprotected, allowing customers to program the sector after receiv-
ing the device. The customer-lockable version also has the SecSi Sector Indicator
Bit permanently set to a “0.” The factory-locked version is always protected when
shipped from the factory, and has the SecSi (Secured Silicon) Sector Indicator Bit
permanently set to a “1.” Thus, the SecSi Sector Indicator Bit prevents customer-
lockable devices from being used to replace devices that are factory locked. Note
