A d v a n c e I n f o r m a t i o n
using the Persistent Sector Protection method, they must set the Persistent
Sector Protection Mode Locking Bit. This will permanently set the part to op-
erate only using Persistent Sector Protection. If the customer decides to use the
password method, they must set the Password Mode Locking Bit. This will
permanently set the part to operate only using password sector protection.
It is important to remember that setting either the Persistent Sector Protec-
tion Mode Locking Bit or the Password Mode Locking Bit permanently
selects the protection mode. It is not possible to switch between the two methods
once a locking bit has been set. It is important that one mode is explicitly
selected when the device is first programmed, rather than relying on the
default mode alone. This is so that it is not possible for a system program or
virus to later set the Password Mode Locking Bit, which would cause an unex-
pected shift from the default Persistent Sector Protection Mode into the Password
Protection Mode.
The device is shipped with all sectors unprotected. The factory offers the option
of programming and protecting sectors at the factory prior to shipping the device
through the ExpressFlash™ Service. Contact your sales representative for details.
It is possible to determine whether a sector is protected or unprotected. See “Au-
toselect Command Sequence” section on page 58 for details.
Advanced Sector Protection
Advanced Sector Protection features several levels of sector protection, which can
disable both the program and erase operations in certain sectors.
Persistent Sector Protection is a method that replaces the old 12V controlled
protection method.
Password Sector Protection is a highly sophisticated protection method that
requires a password before changes to certain sectors are permitted.
Advanced Sector Protection is available when ACC = VHH
.
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
will abort 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 uti-
lizing the Write Buffer of the device. During a Lock Register programming
sequence execution, the DQ6 Toggle Bit I will toggle 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. Initial access
delay is required to read the Lock Register.
The Customer SecSi 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 Reg-
ister. 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 SecSi Sector and then set
the device either permanently into Password Protection Mode or Persistent Pro-
tection Mode and then lock the SEcSi Sector at separate instances and time
frames.
46
S29GLxxxN MirrorBitTM Flash Family
27631A4 May 13, 2004
SPANSION [ SPANSION ]
