X28HC64_09 Datasheet, PDF (6/17 Pages) Intersil Corporation – 5 Volt, Byte Alterable EEPROM

Software Data Protection
V_CC
0V
DATA
ADDR
CE
AAA
1555
55
0AAA
WE
X28HC64
A0
1555
≤t_{BLC MAX}
WRITES
OK
t_WC
BYTE
OR
PAGE
(V_CC)
WRITE
PROTECTED
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
FIGURE 6. TIMING SEQUENCE—BYTE OR PAGE WRITE
Regardless of whether the device has previously been
protected or not, once the software data protection algorithm
is used, the X28HC64 will automatically disable 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.
BYTE/PAGE
LOAD ENABLED
OPTIONAL
BYTE/PAGE
LOAD OPERATION
AFTER T_WC
RE-ENTERS DATA
PROTECTED STATE
FIGURE 7. WRITE SEQUENCE FOR SOFTWARE DATA
PROTECTION
6
FN8109.2
August 28, 2009