EN29LV641H/L EN29LV640U
protected sector group. A sector group consists of four adjacent sectors that would be protected at the
same time. Please see Table 2 which show the organization of sector groups.
There are two methods to enable this hardware protection circuitry. The first one requires only that the
RESET# pin be at VID and then standard microprocessor timings can be used to enable or disable this
feature. See Flowchart 6a and 6b for the algorithm and Figure 11 for the timings.
When doing Sector Group Unprotect, all the unprotected sector groups must be protected prior to any
unprotect write cycle.
The second method is for programming equipment. This method requires VID to be applied to both OE#
and A9 pins and non-standard microprocessor timings are used. This method is described in a
separate document, the Datasheet Supplement of EN29LV641H/L / EN29LV640U, which can be
obtained by contacting a representative of Eon Silicon Solution, Inc.
WP#: Write Protect
The Write Protect function provides a hardware method to protect the first or last sector against erase
and program without using VID.
When WP# is Low, the device protects the first or last sector regardless of whether these sectors were
previously protected or unprotected using the method described in “Sector Group Protection &
Unprotection”, Program and Erase operations in these sectors are ignored.
When WP# is High, the device reverts to the previous protection status of the first or last sector.
Program and Erase operations can now modify the data in those sectors unless the sector is protected
using Sector Group Protection.
Note that the WP# pin must not be left floating or unconnected.
Temporary Sector Group Unprotect
Start
This feature allows temporary unprotection of previously protected
sector groups to change data while in-system. The Temporary
Sector Group Unprotect mode is activated by setting the RESET#
pin to VID. During this mode, formerly protected sector groups can
be programmed or erased by simply selecting the sector group
addresses. Once VID is removed from the RESET# pin, all the
previously protected sector groups are protected again. See
accompanying flowchart and timing diagrams in Figure 10 for more
details.
Reset#=VID (note 1)
Perform Erase or Program
Operations
RESET#=VIH
Temporary Sector Group
Unprotect Completed (note 2)
Notes:
1. All protected sector groups are unprotected. (If
WP#=VIL, the first or last sector will remain
protected.)
2. Previously protected sector groups are protected
again.
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
©2005 Eon Silicon Solution, Inc., www.essi.com.tw
13
Rev. B, Issue Date: 2005/06/27
EON [ EON SILICON SOLUTION INC. ]
