The alternate method intended only for programming
equipment requires VID on address pin A9 and OE#.
This method is compatible with programmer routines
written for earlier 3.0 volt-only AMD flash devices.
Publication number 22244 contains further details;
contact an AMD representative to request a copy.
Temporary Sector Unprotect
(Note: For the following discussion, the term “sector”
applies to both sectors and sector blocks. A sector
block consists of two or more adjacent sectors that are
protected or unprotected at the same time (Tables 2
and 4).
The device is shipped with all sectors unprotected.
AMD offers the option of programming and protecting
sectors at its factory prior to shipping the device
through AMD’s ExpressFlash™ Service. Contact an
AMD representative for details.
This feature allows temporary unprotection of previ-
ously protected sectors to change data in-system. The
Sector Unprotect mode is activated by setting the RE-
SET# pin to VID. During this mode, formerly protected
sectors can be programmed or erased by selecting the
sector addresses. Once VID is removed from the RE-
SET# pin, all the previously protected sectors are
protected again. Figure 1 shows the algorithm, and
Figure 25 shows the timing diagrams, for this feature.
It is possible to determine whether a sector is pro-
tected or unprotected. See the Autoselect Mode sec-
tion for details.
Write Protect (WP#)
The Write Protect function provides a hardware
method of protecting certain boot sectors without
using VID. This function is one of two provided by the
WP#/ACC pin.
START
If the system asserts VIL on the WP#/ACC pin, the de-
vice disables program and erase functions in the two
“outermost” 8 Kbyte boot sectors independently of
whether those sectors were protected or unprotected
using the method described in “Sector/Sector Block
Protection and Unprotection”. The two outermost 8
Kbyte boot sectors are the two sectors containing the
lowest addresses in a bottom-boot-configured device,
or the two sectors containing the highest addresses in
a top-boot-configured device.
RESET# = VID
(Note 1)
Perform Erase or
Program Operations
RESET# = VIH
If the system asserts VIH on the WP#/ACC pin, the de-
vice reverts to whether the two outermost 8K Byte
boot sectors were last set to be protected or unpro-
tected. That is, sector protection or unprotection for
these two sectors depends on whether they were last
protected or unprotected using the method described
in “Sector/Sector Block Protection and Unprotection”.
Temporary Sector
Unprotect Completed
(Note 2)
Notes:
Note that the WP#/ACC pin must not be left floating or
unconnected; inconsistent behavior of the device may
result.
1. All protected sectors unprotected (If WP#/ACC = VIL,
outermost boot sectors will remain protected).
2. All previously protected sectors are protected once
again.
Figure 1. Temporary Sector Unprotect Operation
18
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September 27, 2004
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