AM29DL323GT90WMI AMD (ADVANCED MICRO DEVICES), AM29DL323GT90WMI Datasheet - Page 53

• Manufacturer Part Number: AM29DL323GT90WMI
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of AM29DL323GT90WMI

• Lead Free Status / Rohs Status: Not Compliant

March 15, 2004 31107A5
64-bit Password
Write Protect (WP#)
flash device; therefore each password should be different for every flash device.
While programming in the password region, the customer may perform Password
Verify operations.
Once the desired password is programmed in, the customer must then set the
Password Mode Locking Bit. This operation achieves two objectives:
Permanently sets the device to operate using the Password Protection Mode. It is
not possible to reverse this function.
Disables all further commands to the password region. All program, and read op-
erations are ignored.
Both of these objectives are important, and if not carefully 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 set-
ting 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 Persis-
tent Sector Protection Locking Bit is disabled from programming, guaranteeing
that no changes to the protection scheme are allowed.
The 64-bit Password is located in its own memory space and is accessible through
the use of the Password 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 command from
reading the contents of the password on the pins of the device.
The Write Protect feature provides a hardware method of protecting the upper
two and lower two sectors without using V
pin and overrides the previously discussed
tion method.
If the system asserts V
erase functions in the two outermost 4 Kword sectors on both ends of the flash
array independent of whether it was previously protected or unprotected.
If the system asserts V
and lower two sectors to whether they were last set to be protected or unpro-
tected. That is, sector protection or unprotection for these sectors depends on
whether they were last protected or unprotected using the method described in
the
Note that the WP#/ACC pin must not be left floating or unconnected; inconsistent
behavior of the device may result.
Persistent Protection Bit Lock
The Persistent Protection Bit (PPB) Lock is a volatile bit that reflects the state of
the Password Mode Locking 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
"High Voltage Sector
P R E L I M I N A R Y
S29PL127J/S29PL129J/S29PL064J/S29PL032J
IH
IL
Protection" section.
on the WP#/ACC pin, the device disables program and
on the WP#/ACC pin, the device reverts the upper two
ID
. This function is provided by the WP#
"High Voltage Sector
Protection" sec-
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