MBM29QM12DH Fujitsu Microelectronics, Inc., MBM29QM12DH Datasheet - Page 38

• Manufacturer Part Number: MBM29QM12DH
• Description: Page Mode Flash Memory 128m 8m X 16 Bit
• Manufacturer: Fujitsu Microelectronics, Inc.

Password Program Command
Password Verify Command
Password Protection Mode Locking Bit Program Command
Persistent Sector Protection Mode Locking Bit Program Command
PPB Lock Bit Set Command
The Password Program Command permits programming the password that is used as part of the hardware
protection scheme. The actual password is 64-bits long. 4 Password Program commands are required to program
the password. The user must enter the unlock cycle, password program command (38h) and the program
address/data for each portion of the password when programming. There are no provisions for entering the 2-
cycle unlock cycle, the password program command, and all the password data. There is no special addressing
order required for programming the password. Also, when the password is undergoing programming, Simulta-
neous Operation is disabled. Read operations to any memory location will return the programming status. Once
the Password is written and verified, the Password Mode Locking Bit must be set in order to prevent verification.
The Password Program Command is only capable of programming “0”s. Programming a “1” after a cell is
programmed as a “0” results in a time-out by the Embedded Program Algorithm with the cell remaining as a “0”.
The password is all F’s when shipped from the factory. All 64-bit password combinations are valid as a password.
Writing the HiddenROM Exit command returns the device back to normal operation.
The Password Verify Command is used to verify the Password. The Password is verifiable only when the Password
Mode Locking Bit is not programmed. If the Password Mode Locking Bit is programmed and the user attempts
to verify the Password, the device will always drive all F’s onto the DQ data bus.
Also, the device will not operate in Simultaneous Operation when the Password Verify command is executed.
Only the password is returned regardless of the bank address. The lower two address bits (A
the Password Verify. Writing the HiddenROM Exit command returns the device back to normal operation.
The Password Protection Mode Locking Bit Program Command programs the Password Protection Mode Locking
Bit, which prevents further verifies or updates to the Password. Once programmed, the Password Protection
Mode Locking Bit cannot be erased. Once the Password Protection Mode Locking Bit is programmed, the
Presistent Sector Protection Locking Bit program circuitry is disabled, thereby forcing the device to remain in
the Password Protection mode. After issuing "PL/68h" at 4th bus cycle, the device requires approximately 150 µs
time out period for programming the Password Protection Mode Locking Bit. Then by writing "PL/48h" at 5th bus
cycle, the device outputs verify data at DQ
If not, then the user needs to repeat this program sequence from the 4th cycle of "PL/68h". Exiting the Password
Protection Mode Locking Bit Program command is accomplished by writing the HiddenROM Exit command.
The Persistent Sector Protection Mode Locking Bit Program Command programs the Persistent Sector Protection
Mode Locking Bit, which prevents the Password Mode Locking Bit from ever being programmed. By disabling
the program circuitry of the Password Mode Locking Bit, the device is forced to remain in the Persistent Sector
Protection mode of operation, once this bit is set. After issuing "SPML/68h" at 4th bus cycle, the device requires
approximately 150 µs time out period for programming the Persistent Protection Mode Locking Bit. Then by
writing "SPML/48h" at 5th bus cycle, the device outputs verify data at DQ
Mode Locking Bit is programmed. If not, then the user needs to repeat this program sequence from the 4th cycle
of "SPML/68h". Exiting the Persistent Protection Mode Locking Bit Program command is accomplished by writing
the HiddenROM Exit command.
The PPB Lock Bit Set command is used to set the PPB Lock bit if it is cleared either at reset or if the Password
Unlock command was successfully executed. There is no PPB Lock Bit Clear command. Once the PPB Lock
Bit is set, it cannot be cleared unless the device is taken through a power-on clear or the Password Unlock
command is executed. If the Password Mode Locking Bit is set, the PPB Lock Bit status is reflected as set, even
after a power-on reset cycle. Exiting the PPB Lock Bit Set command is accomplished by writing the HiddenROM
Exit command.
0
. If DQ
0
1 then Password Protection Mode Locking Bit is programmed.
MBM29QM12DH
0
. If DQ
0
1 then Persistent Protection
1
:A
0
) are valid during
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