A d v a n c e I n f o r m a t i o n
All PPB Erase Command
The All PPB Erase command is used to erase all PPBs in bulk. There is no means
for individually erasing a specific PPB. Unlike the PPB program, no specific sector
address is required. However, when the PPB erase command is written (60h) and
A6 = 1, all Sector PPBs are erased in parallel. If the PPB Lock Bit is set the ALL
PPB Erase command will not execute and the command will time-out without
erasing the PPBs. The host system must determine whether all PPB has been fully
erased by noting the status of DQ0 in the sixth cycle of the All PPB Erase com-
mand. If DQ0 = 1, the entire six-cycle All PPB Erase command sequence must be
reissued until DQ0 = 1.
It is the responsibility of the user to preprogram all PPBs prior to issuing the All
PPB Erase command. If the user attempts to erase a cleared PPB, over-erasure
may occur making it difficult to program the PPB at a later time. Also note that
the total number of PPB program/erase cycles is limited to 100 cycles. Cycling the
PPBs beyond 100 cycles is not guaranteed.
The All PPB Erase command is permitted if the SecSi sector is enabled.
DYB Write
The DYB Write command is used for setting the DYB, which is a volatile bit that
is cleared at reset. There is one DYB per sector. If the PPB is set, the sector is
protected regardless of the value of the DYB. If the PPB is cleared, setting the
DYB to a 1 protects the sector from programs or erases. Since this is a volatile
bit, removing power or resetting the device will clear the DYBs. The bank address
is latched when the command is written.
The DYB Write command is permitted if the SecSi sector is enabled.
PPB Lock Bit Set
The PPB Lock Bit set command is used for setting the DYB, which is a volatile bit
that is cleared at reset. There is one DYB per sector. If the PPB is set, the sector
is protected regardless of the value of the DYB. If the PPB is cleared, setting the
DYB to a 1 protects the sector from programs or erases. Since this is a volatile
bit, removing power or resetting the device will clear the DYBs. The bank address
is latched when the command is written.
The PPB Lock command is permitted if the SecSi sector is enabled.
DYB Status
The programming of the DYB for a given sector can be verified by writing a DYB
status verify command to the device.
PPB Status
The programming of the PPB for a given sector can be verified by writing a PPB
status verify command to the device.
PPB Lock Bit Status
The programming of the PPB Lock Bit for a given sector can be verified by writing
a PPB Lock Bit status verify command to the device.
Non-volatile Protection Bit Program And Erase Flow
The device uses a standard command sequence for programming or erasing the
SecSi Sector Protection, Password Locking, Persistent Sector Protection Mode
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