AM29PDL128G Datasheet, PDF (40/69 Pages) SPANSION – 128 Megabit (8 M x 16-Bit/4 M x 32-Bit) CMOS 3.0 Volt-only, Simultaneous Read/ Write Flash Memory with VersatileIO Control

PRELIMINARY
DYB Write Command
The DYB Write command is used to set or clear a DYB
for a given sector. The high order address bits
(A21–A11) are issued at the same time as the code
01h or 00h on DQ7-DQ0. All other DQ data bus pins
are ignored during the data write cycle. The DYBs are
modifiable at any time, regardless of the state of the
PPB or PPB Lock Bit. The DYBs are cleared at
power-up or hardware reset.Exiting the DYB Write
command is accomplished by writing the Read/Reset
command.
The DYB Write command is permitted if the SecSi
sector is enabled.
Password Unlock Command
The Password Unlock command is used to clear the
PPB Lock Bit so that the PPBs can be unlocked for
modification, thereby allowing the PPBs to become ac-
cessible for modification. The exact password must be
entered in order for the unlocking function to occur.
This command cannot be issued any faster than 2 µs
at a time to prevent a hacker from running through the
all 64-bit combinations in an attempt to correctly match
a password. If the command is issued before the 2 µs
execution window for each portion of the unlock, the
command will be ignored.
The Password Unlock function is accomplished by
writing Password Unlock command and data to the
device to perform the clearing of the PPB Lock Bit.
The password is 64 bits long, so the user must write
the Password Unlock command 2 times for a x32 bit
data bus and 4 times for a x16 data bus.
Once the Password Unlock command is entered, the
RY/BY# pin goes LOW indicating that the device is
busy. Approximately 2 µs is required for each portion
of the unlock. Once the first portion of the password
unlock completes (RY/BY# is not driven and DQ6
does not toggle when read), the Password Unlock
command is issued again, only this time with the next
part of the password. If WORD# = 1, the second Pass-
word Unlock command is the final command before
the PPB Lock Bit is cleared (assuming a valid pass-
word). If WORD# = 0, this is the fourth Password Un-
lock 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 successive read op-
erations until complete. It is the responsibility of the
microprocessor to keep track of the number of Pass-
word 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 (A21–A11) are written at
the same time as the program command 60h with A6
= 0. If the PPB Lock Bit is set and the corresponding
PPB is set for the sector, the PPB Program command
will not execute and the command will time-out without
programming the PPB.
After programming a PPB, two additional cycles are
needed to determine whether the PPB has been pro-
grammed with margin. If the PPB has been pro-
grammed without margin, the program command
should be reissued to improve the program margin.
The PPB Program command is permitted if the SecSi
sector is enabled. The PPB Program command does
not follow the Embedded Program algorithm.
All PPB Erase Command
The All PPB Erase command is used to erase all
PPBs in bulk. There is no means for individually eras-
ing a specific PPB. Unlike the PPB program, no spe-
cific sector address is required. However, when the
PPB erase command is written (60h) and A6 = 1, all
Sector 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. After erasing the PPBs, two additional cycles
are needed to determine whether the PPB has been
erased with margin. If the PPBs has been erased with-
out margin, the erase command should be reissued to
improve the program margin.
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 guaranteed.
The All PPB Erase command is permitted if the SecSi
sector is enabled.
DYB Write Command
The DYB Write command is used for setting the DYB,
which is a volatile bit that is cleared at hardware 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 vol-
atile bit, removing power or resetting the device will
clear the DYBs. The bank address is latched when the
command is written.
July 29, 2002
Am29PDL128G
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