Sector protection and unprotection requires V on the RESET# pin only, and can
ID
be implemented either in-system or via programming equipment. Figure 2 shows
the algorithms and Figure 23 shows the timing diagram. This method uses stan-
dard microprocessor bus cycle timing. For sector unprotect, all unprotected
sectors must first be protected prior to the first sector unprotect write cycle.
Temporary Sector Unprotect
This feature allows temporary unprotection of previously protected sectors to
change data in-system. The Sector Unprotect mode is activated by setting the
RESET# pin to V . During this mode, formerly protected sectors can be pro-
ID
grammed or erased by selecting the sector addresses. Once V is removed from
ID
the RESET# pin, all the previously protected sectors are protected again. Figure
shows the algorithm, and Figure 22 shows the timing diagrams, for this feature.
START
RESET# = VID
(Note 1)
Perform Erase or
Program Operations
RESET# = VIH
Temporary Sector
Unprotect Completed
(Note 2)
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once again.
Figure 1. Temporary Sector Unprotect Operation
17
S29AL016M
S29AL016M_00A4 April 21, 2004
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