MX29LV640BT/BB
FACTORY LOCKED:Secured Silicon Sector
Programmed and Protected At the Factory
In device with an ESN, the Secured Silicon Sector is
protected when the device is shipped from the factory.
The Secured Silicon Sector cannot be modified in any
way.A factory locked device has an 8-word random ESN
at address 3FFF70h-3FFF77h (for MX29LV640BT) or
000000h-000007h (for MX29LV640BB).
CUSTOMER LOCKABLE:Secured Silicon
Sector NOT Programmed or Protected At the
Factory
As an alternative to the factory-locked version, the device
may be ordered such that the customer may program
and protect the 128-word Secured Silicon Sector.
Programming and protecting the Secured Silicon Sector
must be used with caution since, once protected, there
is no procedure available for unprotected the Secured
Silicon Sector area and none of the bits in the Secured
Silicon Sector memory space can be modified in any
way.
The Secured Silicon Sector area can be protected using
one of the following procedures:
Write the three-cycle Enter Secured Silicon Sector Region
command sequence, and then follow the in-system
sector protect algorithm as shown in Figure 14, except
that RESET# may be at eitherVIH orVID.This allows in-
system protection of the Secured Silicon Sector without
raising any device pin to a high voltage. Note that method
is only applicable to the Secured Silicon Sector.
Write the three-cycle Enter Secured Silicon Sector Region
command sequence, and then alternate method of sector
protection described in the :Sector Group Protection and
Unprotect" section.
Once the Secured Silicon Sector is programmed, locked
and verified, the system must write the Exit Secured
Silicon Sector Region command sequence to return to
reading and writing the remainder of the array.
P/N:PM1076
REV. 1.2, SEP. 07, 2005
20
Macronix [ MACRONIX INTERNATIONAL ]
