參數(shù)資料
型號: W78M32V100BC
廠商: WHITE ELECTRONIC DESIGNS CORP
元件分類: PROM
英文描述: 8M X 32 FLASH 3.3V PROM, 100 ns, PBGA159
封裝: 13 X 22 MM, 1.27 MM PITCH, PLASTIC, BGA-159
文件頁數(shù): 8/54頁
文件大小: 789K
代理商: W78M32V100BC
16
White Electronic Designs Corporation (602) 437-1520 www.whiteedc.com
White Electronic Designs
W78M32V-XBX
April 2006
Rev. 3
White Electronic Designs Corp. reserves the right to change products or specications without notice.
SECTOR PROTECTION
The device features several levels of sector protection,
which can disable both the program and erase operations
in certain sectors or sector groups:
Persistent Sector Protection
A command sector protection method that replaces the old
12 V controlled protection method.
Password Sector Protection
A highly sophisticated protection method that requires
a password before changes to certain sectors or sector
groups are permitted
WP# Hardware Protection
A write protect pin that can prevent program or erase
operations in sectors 0, 1, 268, and 269.
The WP# Hardware Protection feature is always available,
independent of the software managed protection method
chosen.
Selecting a Sector Protection Mode
All parts default to operate in the Persistent Sector
Protection mode. The user must then choose if the
Persistent or Password Protection method is most desirable.
There are two one-time programmable non-volatile bits
that dene which sector protection method will be used.
If the Persistent Sector Protection method is desired,
programming the Persistent Sector Protection Mode
Locking Bit
permanently sets the device to the Persistent
Sector Protection mode. If the Password Sector Protection
method is desired, programming the Password Mode
Locking Bit
permanently sets the device to the Password
Sector Protection mode. It is not possible to switch between
the two protection modes once a locking bit has been set.
One of the two modes must be selected when the device
is rst programmed
. This prevents a program or virus from
later setting the Password Mode Locking Bit, which would
cause an unexpected shift from the default Persistent Sector
Protection Mode into the Password Protection Mode.
The device is shipped with all sectors unprotected.
It is possible to determine whether a sector is protected or
unprotected. See Autoselect Mode for details.
PERSISTENT SECTOR PROTECTION
The Persistent Sector Protection method replaces the 12
V controlled protection method in previous WEDC ash
devices. This new method provides three different sector
protection states:
Persistently Locked—The sector is protected and
cannot be changed.
Dynamically Locked—The sector is protected and
can be changed by a simple command.
Unlocked—The sector is unprotected and can be
changed by a simple command.
To achieve these states, three types of “bits” are used:
Persistent Protection Bit (PPB)
A single Persistent (non-volatile) Protection Bit is assigned
to a maximum four sectors (see the sector address tables
for specic sector protection groupings). All 4 Kword boot-
block sectors have individual sector Persistent Protection
Bits (PPBs) for greater exibility. Each PPB is individually
modiable through the PPB Write Command.
The device erases all PPBs in parallel. If any PPB requires
erasure, the device must be instructed to preprogram all
of the sector PPBs prior to PPB erasure. Otherwise, a
previously erased sector PPBs can potentially be over-
erased. The ash device does not have a built-in means
of preventing sector PPBs over-erasure.
Persistent Protection Bit Lock (PPB Lock)
The Persistent Protection Bit Lock (PPB Lock) is a global
volatile bit. When set to “1”, the PPBs cannot be changed.
When cleared (“0”), the PPBs are changeable. There is
only one PPB Lock bit per device. The PPB Lock is cleared
after power-up or hardware reset. There is no command
sequence to unlock the PPB Lock.
Dynamic Protection Bit (DYB)
A volatile protection bit is assigned for each sector. After
power-up or hardware reset, the contents of all DYBs is
“0”. Each DYB is individually modiable through the DYB
Write Command.
When the parts are rst shipped, the PPBs are cleared, the
DYBs are cleared, and PPB Lock is defaulted to power up in
the cleared state – meaning the PPBs are changeable.
When the device is rst powered on the DYBs power up
cleared (sectors not protected). 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
PPBs cleared, the DYBs control whether or not the sector
is protected or unprotected. By issuing the DYB Write
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