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参数资料
| 型号： | AM29BDD160GB54DKE |
| 厂商： | ADVANCED MICRO DEVICES INC |
| 元件分类： | PROM |
| 英文描述： | 16 Megabit (1 M x 16-bit/512 K x 32-Bit), CMOS 2.5 Volt-only Burst Mode, Dual Boot, Simultaneous Read/Write Flash Memory |
| 中文描述： | 512K X 32 FLASH 2.7V PROM, 54 ns, PQFP80 |
| 封装： | PLASTIC, QFP-80 |
| 文件页数： | 18/80页 |
| 文件大小： | 3476K |
| 代理商： | AM29BDD160GB54DKE |
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Am29BDD160G
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grammed, 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 unexpected
shift from the default Persistent Sector Protection
Mode into the Password Protection Mode.
The WP# Hardware Protection feature is always
available, independent of the software managed pro-
tection method chosen.
Persistent Sector Protection
The Persistent Sector Protection method replaces the
old 12 V controlled protection method while at the
same time enhancing flexibility by providing three
different sector protection states:
■
Persistently Locked—A 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
Persistent Protection Bit (PPB)
A single Persistent (non-volatile) Protection Bit is as-
signed to a maximum of four sectors (see the sector
address tables for specific sector protection group-
ings). All 8 Kbyte boot-block sectors have individual
sector Persistent Protection Bits (PPBs) for greater
flexibility. Each PPB is individually modifiable through
the PPB Write Command.
Note: If a PPB requires erasure, all of the sector
PPBs must first be preprogrammed prior to PPB eras-
ing. All PPBs erase in parallel, unlike programming
where individual PPBs are programmable. It is the
responsibility of the user to perform the preprogram-
ming operation. Otherwise, an already erased sector
PPBs has the potential of being over-erased. There is
no hardware mechanism to prevent sector PPBs
over-erasure.
Persistent Protection Bit Lock (PPB Lock)
A global volatile bit. When set to “1”, the PPBs can-
not be changed. When cleared (“0”), the PPBs are
changeable. There is only one PPB Lock bit per de-
vice. 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 parts 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 unpro-
tect ed. By iss uing the DYB Write co mma nd
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 be-
cause it is very easy to switch back and forth
between the protected and unprotected conditions.
This allows software to easily protect sectors against
inadvertent changes yet does not prevent the easy
removal of protection when changes are needed. The
DYBs maybe set or cleared as often as needed.
The PPBs allow for a more static, and difficult to
change, level of protection. The PPBs retain their
state across power cycles because they are Non-Vol-
atile. Individual PPBs are set with a command but
must all be cleared as a group through a complex se-
quence of program and erasing commands. The PPBs
are limited to 100 erase cycles.
The PPB Lock bit adds an additional level of protec-
tion. Once all PPBs are programmed to the desired
settings, the PPB Lock may be set to “1”. Setting the
PPB Lock disables all program and erase commands
to the Non-Volatile PPBs. In effect, the PPB Lock Bit
locks the PPBs into their current state. The only way
to clear the PPB Lock is to go through a power cycle.
System boot code can determine if any changes to
the PPB are needed e.g. to allow new system code to
be downloaded. If no changes are needed then the
boot code can set the PPB Lock to disable any further
changes to the PPBs during system operation.
The WP# write protect pin adds a final level of hard-
ware protection to the two outermost 8 Kbytes
sectors in the 75% bank. When this pin is low it is
not possible to change the contents of these two sec-
tors.
It is possible to have sectors that have been persis-
tently locked, and sectors that are left in the
dynamic state. The sectors in the dynamic state are
all unprotected. If there is a need to protect some of
them, a simple DYB Write command sequence is all
that is necessary. The DYB write command for the
dynamic sectors switch the DYBs to signify protected
and unprotected, respectively. If there is a need to
change the status of the persistently locked sectors,
a few more steps are required. First, the PPB Lock bit
must be disabled by either putting the device
through a power-cycle, or hardware reset. The PPBs
can then be changed to reflect the desired settings.
Setting the PPB lock bit once again will lock the
PPBs, and the device operates normally again.
Note: to achieve the best protection, it’s recom-
mended to execute the PPB lock bit set command
early in the boot code, and protect the boot code by
holding WP# = V
IL.
相关PDF资料 |
PDF描述 |
|---|---|
| AM29BDD160GB54DKF | 16 Megabit (1 M x 16-bit/512 K x 32-Bit), CMOS 2.5 Volt-only Burst Mode, Dual Boot, Simultaneous Read/Write Flash Memory |
| AM29BDD160GB54DKI | 16 Megabit (1 M x 16-bit/512 K x 32-Bit), CMOS 2.5 Volt-only Burst Mode, Dual Boot, Simultaneous Read/Write Flash Memory |
| AM29BDD160GB54DKK | 16 Megabit (1 M x 16-bit/512 K x 32-Bit), CMOS 2.5 Volt-only Burst Mode, Dual Boot, Simultaneous Read/Write Flash Memory |
| AM29BDD160GB54DPBE | 16 Megabit (1 M x 16-bit/512 K x 32-Bit), CMOS 2.5 Volt-only Burst Mode, Dual Boot, Simultaneous Read/Write Flash Memory |
| AM29BDD160GB54DPBI | 16 Megabit (1 M x 16-bit/512 K x 32-Bit), CMOS 2.5 Volt-only Burst Mode, Dual Boot, Simultaneous Read/Write Flash Memory |
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