X28HC64_09 Datasheet, PDF (7/17 Pages) Intersil Corporation – 5 Volt, Byte Alterable EEPROM

X28HC64
Resetting Software Data Protection
V_CC
DATA
ADDR
CE
AAA
1555
55
0AAA
80
1555
AA
1555
55
0AAA
20
1555
≥t_WC
STANDARD
OPERATING
MODE
WE
FIGURE 8. RESET SOFTWARE DATA PROTECTION TIMING SEQUENCE
WRITE DATA AA
TO ADDRESS
1555
In the event the user wants to deactivate the software data
protection feature for testing or reprogramming in an
EEPROM programmer, the following six step algorithm will
reset the internal protection circuit. After t_WC, the X28HC64
will be in standard operating mode.
WRITE DATA 55
TO ADDRESS
0AAA
Note: Once initiated, the sequence of write operations
should not be interrupted.
WRITE DATA 80
TO ADDRESS
1555
WRITE DATA AA
ADDRESS
1555
WRITE DATA 55
TO ADDRESS
0AAA
WRITE DATA 20
TO ADDRESS
1555
FIGURE 9. SOFTWARE SEQUENCE TO DEACTIVATE
SOFTWARE
7
FN8109.2
August 28, 2009