X28HC64 Datasheet, PDF (7/24 Pages) Xicor Inc. – 5 Volt, Byte Alterable E2PROM

X28HC64
SOFTWARE DATA PROTECTION
Figure 6. Timing Sequence—Byte or Page Write
VCC
0V
DATA
ADDR
CE
AA
1555
55
0AAA
WE
A0
1555
WRITES
OK
tWC
≤tBLC _MAX
BYTE
OR
PAGE
(VCC)
WRITE
PROTECTED
3857 FHD F16
Figure 7. Write Sequence for
Software Data Protection
WRITE DATA AA
TO ADDRESS
1555
WRITE DATA 55
TO ADDRESS
0AAA
WRITE DATA A0
TO ADDRESS
1555
WRITE DATA XX
TO ANY
ADDRESS
WRITE LAST
BYTE TO
LAST ADDRESS
BYTE/PAGE
LOAD ENABLED
OPTIONAL BYTE
OR PAGE WRITE
ALLOWED
Regardless of whether the device has previously been
protected or not, once the software data protection
algorithm is used, the X28HC64 will automatically dis-
able further writes unless another command is issued to
deactivate it. If no further commands are issued the
X28HC64 will be write protected during power-down
and after any subsequent power-up.
Note: Once initiated, the sequence of write operations
should not be interrupted.
AFTER tWC
RE-ENTERS DATA
PROTECTED STATE
3857 FHD F17
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