A d v a n c e I n f o r m a t i o n
cannot be erased! If the Password Protection Mode Locking Bit is verified as pro-
gram without margin, the Password Protection Mode Locking Bit Program
command can be executed to improve the program margin. Once the Password
Protection Mode Locking Bit is programmed, the Persistent Sector Protection
Locking Bit program circuitry is disabled, thereby forcing the device to remain in
the Password Protection mode. Exiting the Mode Locking Bit Program command
is accomplished by writing the Read/Reset command.
The Password Protection Mode Locking Bit Program command is permitted if the
SecSi sector is enabled.
Persistent Sector Protection Mode Locking Bit Program Command
The Persistent Sector Protection Mode Locking Bit Program Command programs
the Persistent Sector Protection Mode Locking Bit, which prevents the Password
Mode Locking Bit from ever being programmed. If the Persistent Sector Protec-
tion Mode Locking Bit is verified as programmed without margin, the Persistent
Sector Protection Mode Locking Bit Program Command should be reissued to im-
prove program margin. By disabling the program circuitry of the Password Mode
Locking Bit, the device is forced to remain in the Persistent Sector Protection
mode of operation, once this bit is set. Exiting the Persistent Protection Mode
Locking Bit Program command is accomplished by writing the Read/Reset
command.
The Persistent Sector Protection Mode Locking Bit Program command is permitted
if the SecSi sector is enabled.
SecSi Sector Protection Bit Program Command
The SecSi Sector Protection Bit Program Command programs the SecSi Sector
Protection Bit, which prevents the SecSi sector memory from being cleared. If the
SecSi Sector Protection Bit is verified as programmed without margin, the SecSi
Sector Protection Bit Program Command should be reissued to improve program
margin. Exiting the V -level SecSi Sector Protection Bit Program Command is
CC
accomplished by writing the Read/Reset command.
The SecSi Sector Protection Bit Program command is permitted if the SecSi sector
is enabled.
PPB Lock Bit Set Command
The PPB Lock Bit Set command is used to set the PPB Lock bit if it is cleared either
at reset or if the Password Unlock command was successfully executed. There is
no PPB Lock Bit Clear command. Once the PPB Lock Bit is set, it cannot be cleared
unless the device is taken through a power-on clear or the Password Unlock com-
mand is executed. Upon setting the PPB Lock Bit, the PPBs are latched into the
DYBs. If the Password Mode Locking Bit is set, the PPB Lock Bit status is reflected
as set, even after a power-on reset cycle. Exiting the PPB Lock Bit Set command
is accomplished by writing the Read/Reset command.
The PPB Lock Bit Set command is permitted if the SecSi sector is enabled.
DYB Write Command
The DYB Write command is used to set or clear a DYB for a given sector. The high
order address bits (A19–A11) are issued at the same time as the code 01h or 00h
on DQ7-DQ0. All other DQ data bus pins are ignored during the data write cycle.
The DYBs are modifiable at any time, regardless of the state of the PPB or PPB
March 22, 2004 30606B0
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SPANSION [ SPANSION ]
