X28VC256 Datasheet, PDF (7/24 Pages) Xicor Inc. – 5 Volt, Byte Alterable E2PROM

X28VC256
SOFTWARE DATA PROTECTION
Figure 6. Timing Sequence—Byte or Page Write
VCC
0V
DATA
ADDRESS
AA
5555
CE
55
2AAA
WE
A0
5555
≤tBLC _MAX
tWC
WRITES
OK
BYTE
OR
PAGE
(VCC)
WRITE
PROTECTED
3869 FHD F16
Figure 7. Write Sequence for
Software Data Protection
WRITE DATA AA
TO ADDRESS
5555
WRITE DATA 55
TO ADDRESS
2AAA
WRITE DATA A0
TO ADDRESS
5555
WRITE DATA XX
TO ANY
ADDRESS
WRITE LAST
BYTE TO
LAST ADDRESS
BYTE/PAGE
LOAD ENABLED
OPTIONAL
BYTE OR
PAGE WRITE
ALLOWED
AFTER tWC
RE-ENTERS DATA
PROTECTED STATE
3869 FHD F17
Regardless of whether the device has previously been
protected or not, once the software data protection
algorithm is used and data has been written, the
X28VC256 will automatically disable further writes un-
less another command is issued to cancel it. If no further
commands are issued the X28VC256 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.
7