D a t a S h e e t
8.11 Lock Register
The Lock Register consists of 3 bits (DQ2, DQ1, and DQ0). These DQ2, DQ1, DQ0 bits of the Lock Register
are programmable by the user. Users are not allowed to program both DQ2 and DQ1 bits of the Lock Register
to the 00 state. If the user tries to program DQ2 and DQ1 bits of the Lock Register to the 00 state, the device
aborts the Lock Register back to the default 11 state. The programming time of the Lock Register is same as
the typical word programming time without utilizing the Write Buffer of the device. During a Lock Register
programming sequence execution, the DQ6 Toggle Bit I toggles until the programming of the Lock Register
has completed to indicate programming status. All Lock Register bits are readable to allow users to verify
Lock Register statuses.
The Customer Secured Silicon Sector Protection Bit is DQ0, Persistent Protection Mode Lock Bit is DQ1, and
Password Protection Mode Lock Bit is DQ2 are accessible by all users. Each of these bits are non-volatile.
DQ15-DQ3 are reserved and must be 1's when the user tries to program the DQ2, DQ1, and DQ0 bits of the
Lock Register. The user is not required to program DQ2, DQ1 and DQ0 bits of the Lock Register at the same
time. This allows users to lock the Secured Silicon Sector and then set the device either permanently into
Password Protection Mode or Persistent Protection Mode and then lock the Secured Silicon Sector at
separate instances and time frames.
Secured Silicon Sector Protection allows the user to lock the Secured Silicon Sector area
Persistent Protection Mode Lock Bit allows the user to set the device permanently to operate in the
Persistent Protection Mode
Password Protection Mode Lock Bit allows the user to set the device permanently to operate in the
Password Protection Mode
Table 8.10 Lock Register
DQ15-3
DQ2
DQ1
DQ0
Password Protection Mode
Lock Bit
Persistent Protection Mode
Lock Bit
Secured Silicon Sector
Protection Bit
Don’t Care
8.12 Persistent Sector Protection
The Persistent Sector Protection method replaces the old 12 V controlled protection method while at the
same time enhancing flexibility by providing three different sector protection states
Dynamically Locked
Persistently Locked
Unlocked
The sector is protected and can be changed by a simple command
A sector is protected and cannot be changed
The sector is unprotected and can be changed by a simple command
To achieve these states, three types of “bits” are used:
8.12.1
Dynamic Protection Bit (DYB)
A volatile protection bit is assigned for each sector. After power-up or hardware reset, the contents of all DYB
bits are in the “unprotected state”. Each DYB is individually modifiable through the DYB Set Command and
DYB Clear Command. When the parts are first shipped, all of the Persistent Protect Bits (PPB) are cleared
into the unprotected state. The DYB bits and PPB Lock bit are defaulted to power up in the cleared state or
unprotected state - meaning the all PPB bits are changeable.
The Protection State for each sector is determined by the logical OR of the PPB and the DYB related to that
sector. For the sectors that have the PPB bits cleared, the DYB bits control whether or not the sector is
protected or unprotected. By issuing the DYB Set and DYB Clear command sequences, the DYB bits is
protected or unprotected, thus placing each sector in the protected or unprotected state. These are the so-
called Dynamic Locked or Unlocked states. They are called dynamic states because it is very easy to switch
back and forth between the protected and un-protected conditions. This allows software to easily protect
sectors against inadvertent changes yet does not prevent the easy removal of protection when changes are
needed.
The DYB bits maybe set or cleared as often as needed. The PPB bits allow for a more static, and difficult to
change, level of protection. The PPB bits retain their state across power cycles because they are Non-
November 16, 2007 S29GL-N_01_09
S29GL-N MirrorBit® Flash Family
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SPANSION [ SPANSION ]
