12 Am29LV800B
PRELIMINARY
Table 4. Am29LV800B Autoselect Codes (High Volta ge Method)
L = Logic Low = V
IL
, H = Logic High = V
IH
, SA = Sector Address, X = Don’t care.
Sector Protection/Unprotection
The hardware sector protection feature disables both
progr am and er ase opera tions in an y sect or. The hard-
ware sector unprotection feature re-enables both pro-
gram and erase operations in previously protected
sectors.
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.
It is possib le to determine whether a sector is protected
or unprotected. See “Autoselect Mode” for details.
Sector Protection/unprotection can be implemented via
two methods.
The primary method requires V
ID
on the RESET# pin
only, and can be implemented either in-system or via
programming equipment. Figure 2 shows the algo-
rithms and Figure 23 shows the timing diagram. This
method uses standard microprocessor bus cycle tim-
ing. For sector unprotect, all unprotected sectors must
first be prote cted prior to the firs t sector unprotec t write
cycle.
The alternate method intended only for programming
equipment requires V
ID
on address pin A9 and OE#.
This method is compatible with programmer routines
written f or earlier 3.0 v olt-only AMD flash de vi ces. Pub-
lication number 20536 contains further details; contact
an AMD representative to request a copy.
Temporary Sector Unprotect
This feature allows temporary unprotection of previ-
ously protected sect ors to change data in-system. The
Sector Unprotect mode is activated by setting the RE-
SET# pin to V
ID
. During this mode, formerly protected
sectors can be prog r ammed or er ased b y selec ting the
sector addresses. Once V
ID
is removed from the RE-
SET# pin, all the previously protected sectors are
protected again. Figure 1 shows the algorithm, and
Figure 22 shows the timing diagrams, for this feature.
Figure 1. Temporary Sector Unprotect Operation
Description Mode CE# OE# WE#
A18
to
A12
A11
to
A10 A9
A8
to
A7 A6
A5
to
A2 A1 A0
DQ8
to
DQ15
DQ7
to
DQ0
Manufacturer ID: AMD L L H X X V
ID
XLXLL X 01h
Device ID:
Am29LV800B
(Top Boot Block)
Word L L H
XXV
ID
XLXLH
22h DAh
Byte L L H X DAh
Device ID:
Am29LV800B
(Bottom Boot
Block)
Word L L H
XXV
ID
XLXLH
22h 5Bh
Byte L L H X 5Bh
Sector Protection V erification L L H SA X V
ID
XLXHL
X
01h
(protected)
X
00h
(unprotected)
START
Perform Erase or
Program Operations
RESET# = V
IH
Temporary Sector
Unprotect Completed
(Note 2)
RESET# = V
ID
(Note 1)
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once
again.
21490E-5
