X28HC256 Xicor, X28HC256 Datasheet - Page 7

• Manufacturer Part Number: X28HC256
• Description: 5 Volt/ Byte Alterable E2PROM
• Manufacturer: Xicor

X28HC256
SOFTWARE DATA PROTECTION
Figure 6. Timing Sequence—Byte or Page Write
Figure 7. Write Sequence for
Software Data Protection
V CC
WE
CE
0V
PROTECTED STATE
RE-ENTERS DATA
WRITE DATA AA
WRITE DATA 55
WRITE DATA XX
LAST ADDRESS
WRITE DATA A0
TO ADDRESS
TO ADDRESS
TO ADDRESS
DATA
ADDRESS
WRITE LAST
AFTER t WC
ADDRESS
BYTE TO
TO ANY
2AAA
5555
5555
5555
AA
BYTE/PAGE
LOAD ENABLED
OPTIONAL
BYTE OR
PAGE WRITE
ALLOWED
2AAA
55
3859 FHD F06
5555
A0
t BLC MAX
t BLC MAX
7
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
X28HC256 will automatically disable further writes un-
less another command is issued to cancel it. If no further
commands are issued the X28HC256 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.
WRITES
PAGE
BYTE
OK
OR
t WC
WRITE
PROTECTED
(V CC )
3859 FHD F16