AM29BDD160G AMD [Advanced Micro Devices], AM29BDD160G Datasheet - Page 44

• Manufacturer Part Number: AM29BDD160G
• Description: 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
• Manufacturer: AMD [Advanced Micro Devices]

command is issued again, only this time with the
next part of the password. If WORD# = 1, the sec-
ond Password Unlock command is the final command
before the PPB Lock Bit is cleared (assuming a valid
password). If WORD# = 0, this is the fourth Pass-
word Unlock command. In x16 mode, four Password
Unlock commands are required to successfully clear
the PPB Lock Bit. As with the first Password Unlock
command, the RY/BY# signal goes LOW and reading
the device results in the DQ6 pin toggling on succes-
sive read operation s un til complete. It is the
responsibility of the microprocessor to keep track of
the number of Password Unlock commands (2 for
x32 bus and 4 for x16 bus), the order, and when to
read the PPB Lock bit to confirm successful password
unlock
The Password Unlock command is permitted if the
SecSi sector is enabled.
PPB Program Command
The PPB Program command is used to program, or
set, a given PPB. Each PPB is individually pro-
grammed (but is bulk erased with the other PPBs).
The specific sector address (A18–A11) are written at
the same time as the program command 60h with
A6 = 0. If the PPB Lock Bit is set and the corre-
sponding PPB is set for the sector, the PPB Program
command will not execute and the command will
time-out without programming the PPB.
The host system must determine whether a PPB has
been fully programmed by noting the status of DQ0
in the sixth cycle of the PPB Program command. If
DQ0 = 0, the entire six-cycle PPB Program command
sequence must be reissued until DQ0 = 1.
The All PPB Erase command is used to erase all PPBs
in bulk. There is no means for individually erasing a
specific PPB. Unlike the PPB program, no specific
sector address is required. However, when the PPB
erase command is written (60h) and A6 = 1, all Sec-
tor PPBs are erased in parallel. If the PPB Lock Bit is
set the ALL PPB Erase command will not execute and
the command will time-out without erasing the PPBs.
The host system must determine whether all PPB has
been fully erased by noting the status of DQ0 in the
sixth cycle of the All PPB Erase command. If DQ0 =
1, the entire six-cycle All PPB Erase command se-
quence must be reissued until DQ0 = 1.
It is the responsibility of the user to preprogram all
PPBs prior to issuing the All PPB Erase command. If
the user attempts to erase a cleared PPB, over-era-
sure may occur making it difficult to program the
PPB at a later time. Also note that the total number
of PPB program/erase cycles is limited to 100 cycles.
Cycling the PPBs beyond 100 cycles is not guaran-
teed.
The All PPB Erase command is permitted if the SecSi
sector is enabled.
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Am29BDD160G
DYB Write
The DYB Write command is used for setting the DYB,
which is a volatile bit that is cleared at reset. There is
one DYB per sector. If the PPB is set, the sector is
protected regardless of the value of the DYB. If the
PPB is cleared, setting the DYB to a 1 protects the
sector from programs or erases. Since this is a vola-
tile bit, removing power or resetting the device will
clear the DYBs. The bank address is latched when
the command is written.
The DYB Write command is permitted if the SecSi
sector is enabled.
PPB Lock Bit Set
The PPB Lock Bit set command is used for setting the
DYB, which is a volatile bit that is cleared at reset.
There is one DYB per sector. If the PPB is set, the
sector is protected regardless of the value of the
DYB. If the PPB is cleared, setting the DYB to a 1
protects the sector from programs or erases. Since
this is a volatile bit, removing power or resetting the
device will clear the DYBs. The bank address is
latched when the command is written.
The PPB Lock command is permitted if the SecSi sec-
tor is enabled.
DYB Status
The programming of the DYB for a given sector can
be verified by writing a DYB status verify command
to the device.
The programming of the PPB for a given sector can
be verified by writing a PPB status verify command
to the device.
PPB Lock Bit Status
The programming of the PPB Lock Bit for a given sec-
tor can be verified by writing a PPB Lock Bit status
verify command to the device.
Non-volatile Protection Bit Program And
Erase Flow
The device uses a standard command sequence for
programming or erasing the SecSi Sector Protection,
Password Locking, Persistent Sector Protection Mode
Locking, or Persistent Protection Bits. Unlike devices
that have the Single High Voltage Sector Unprotect/
Protect feature, the Am29BDD160 has the standard
two-cycle unlock followed by 60h, which places the
device into non-volatile bit program or erase mode.
Once the mode is entered, the specific non-volatile
bit status is read on DQ0. Figure 4 shows a typical
flow for programming the non-volatile bit and Figure
5 shows a typical flow for erasing the non-volatile
bits. The SecSi Sector Protection, Password Locking,
Persistent Sector Protection Mode Locking bits are
not erasable after they are programmed. However,
the PPBs are both erasable and programmable (de-
pending upon device security).
Unlike Single High Voltage Sector Protect/Unprotect,
the A6 pin no longer functions as the program/erase