am49pdl129bh85it Meet Spansion Inc., am49pdl129bh85it Datasheet - Page 37
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am49pdl129bh85it
Manufacturer Part Number
am49pdl129bh85it
Description
Stacked Multi-chip Package Mcp Flash Memory And Psram, 128 Megabit 8m ? 16-bit Cmos 3.0 Volt-only, Simultaneous Operation Flash Memory And 32 Mbit 2m ? 16-bit Cmos Pseudo Static Ram With Page Mode
Manufacturer
Meet Spansion Inc.
Datasheet
1.AM49PDL129BH85IT.pdf
(86 pages)
SECTOR PROTECTION
The Am29PDL127H/Am29PDL129H 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 sec-
tor 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, re-
gardless of which of the other two methods are cho-
sen.
Selecting a Sector Protection Mode
The device defaults to the Persistent Sector Protection
mode. However, to prevents a program or virus from
later setting the Password Mode Locking Bit, which
would cause an unexpected shift from the default Per-
sistent Sector Protection Mode into the Password Pro-
tection Mode, it is recommended that either of two
one-time programmable non-volatile bits that perma-
nently define which sector protection method be set
before the device is first programmed. The Persis-
tent Sector Protection Mode Locking Bit perma-
nently sets the device to the Persistent Sector
Protection mode. 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.
The device is shipped with all sectors unprotected.
AMD offers the option of programming and protecting
sectors at the factory prior to shipping the device
through AMD’s ExpressFlash™ Service. Contact an
AMD representative for details.
It is possible to determine whether a sector is pro-
tected or unprotected. See
quence
Persistent Sector Protection
The Persistent Sector Protection method replaces the
12 V controlled protection method in previous AMD
flash devices. This new method provides three differ-
ent sector protection states:
December 16, 2003
Persistently Locked—The sector is protected and
cannot be changed.
for details.
Autoselect Command Se-
A D V A N C E
Am49PDL127BH/Am49PDL129BH
I N F O R M A T I O N
To achieve these states, three types of “bits” are used:
Persistent Protection Bit (PPB)
A single Persistent (non-volatile) Protection Bit is as-
signed to a maximum four sectors (see the sector ad-
dress tables for specific sector protection groupings).
All 4 Kword boot-block sectors have individual sector
Persistent Protection Bits (PPBs) for greater flexibility.
Each PPB is individually modifiable through the PPB
Write Command.
The device erases all PPBs in parallel. If any PPB re-
quires erasure, the device must be instructed to pre-
program all of the sector PPBs prior to PPB erasure.
Otherwise, a previously erased sector PPBs can po-
tentially be over-erased. The flash 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 glo-
bal volatile bit. When set to “1”, the PPBs cannot be
changed. When cleared (“0”), the PPBs are change-
able. 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 modifiable
through the DYB Write Command.
When the par ts are first shipped, the PPBs are
cleared, the DYBs are cleared, and PPB Lock is de-
faulted to power up in the cleared state – meaning the
PPBs are changeable.
When the device is first 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 command sequences, the
DYBs will be set or cleared, thus placing each sector in
the protected or unprotected state. These are the
so-called Dynamic Locked or Unlocked states. They
are called dynamic states because it is very easy to
switch back and forth between the protected and un-
protected conditions. This allows software to easily
protect sectors against inadvertent changes yet does
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.
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