AM29PDL128G70 SPANSION [SPANSION], AM29PDL128G70 Datasheet - Page 27

• Manufacturer Part Number: AM29PDL128G70
• Description: 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
• Manufacturer: SPANSION [SPANSION]

1. It permanently sets the device to operate using the
2. It also disables all further commands to the pass-
Both of these objectives are important, and if not care-
fully considered, may lead to unrecoverable errors.
The user must be sure that the Password Protection
method is desired when setting the Password Mode
Locking Bit. More importantly, the user must be sure
that the password is correct when the Password Mode
Locking Bit is set. Due to the fact that read operations
are disabled, there is no means to verify what the
password is afterwards. If the password is lost after
setting the Password Mode Locking Bit, there will be
no way to clear the PPB Lock bit.
The Password Mode Locking Bit, once set, prevents
reading the 64-bit password on the DQ bus and further
password programming. The Password Mode Locking
Bit is not erasable. Once Password Mode Locking Bit
is programmed, the Persistent Sector Protection Lock-
ing Bit is disabled from programming, guaranteeing
that no changes to the protection scheme are allowed.
64-bit Password
The 64-bit Password is located in its own memory
space and is accessible through the use of the Pass-
word Program and Verify commands (see “Password
Verify Command”). The password function works in
conjunction with the Password Mode Locking Bit,
which when set, prevents the Password Verify com-
mand from reading the contents of the password on
the pins of the device.
Write Protect (WP#)
The Write Protect feature provides a hardware method
of protecting sectors 0, 1, 268, and 269 without using
V
rides the previously discussed Sector Protection/Un-
protection method.
26
ID
. This function is provided by the WP# pin and over-
Password Protection Mode. It is not possible to re-
verse this function.
word region. All program, and read operations are
ignored.
P R E L I M I N A R Y
Am29PDL128G
If the system asserts V
disables program and erase functions in sectors 0, 1,
268, and 269 independent of whether it was previously
protected or unprotected using
Protection.
If the system asserts V
reverts to whether sectors 0, 1, 268, and 269 were last
set to be protected or unprotected. That is, sector pro-
tection or unprotection for these sectors depends on
whether they were previously protected or unprotected
using
Persistent Protection Bit Lock
The Persistent Protection Bit (PPB) Lock is a volatile
bit that reflects the state of the Password Mode Lock-
ing Bit after power-up reset. If the Password Mode
Lock Bit is also set after a hardware reset (RESET#
asserted) or a power-up reset. The ONLY means for
clearing the PPB Lock Bit in Password Protection
Mode is to issue the Password Unlock command. Suc-
cessful execution of the Password Unlock command
clears the PPB Lock Bit, allowing for sector PPBs
modifications. Asserting RESET#, taking the device
through a power-on reset, or issuing the PPB Lock Bit
Set command sets the PPB Lock Bit to a “1” when the
Password Mode Lock Bit is not set.
If the Password Mode Locking Bit is not set, including
Persistent Protection Mode, the PPB Lock Bit is
cleared after power-up or hardware reset. The PPB
Lock Bit is set by issuing the PPB Lock Bit Set com-
mand. Once set the only means for clearing the PPB
Lock Bit is by issuing a hardware or power-up reset.
The Password Unlock command is ignored in Persis-
tent Protection Mode.
High Voltage Sector Protection
Sector protection and unprotection may also be imple-
mented using programming equipment. The proce-
dure requires high voltage (V
RESET# pin. Refer to
cedure. Note that for sector unprotect, all unprotected
sectors must first be protected prior to the first sector
write cycle.
High Voltage Sector
Figure 1
IH
IL
on the WP# pin, the device
on the WP# pin, the device
Protection.
ID
for details on this pro-
) to be placed on the
High Voltage Sector
July 29, 2002