X28C256D-20 XICOR [Xicor Inc.], X28C256D-20 Datasheet - Page 7

• Manufacturer Part Number: X28C256D-20
• Description: 5 Volt, Byte Alterable E2PROM
• Manufacturer: XICOR [Xicor Inc.]

X28C256
SOFTWARE DATA PROTECTION
Figure 6. Timing Sequence—Byte or Page Write
Figure 7. Write Sequence for
Software Data Protection
PROTECTED STATE
RE-ENTERS DATA
V CC
WE
CE
WRITE DATA 55
WRITE DATA AA
WRITE DATA XX
LAST ADDRESS
WRITE DATA A0
0V
TO ADDRESS
TO ADDRESS
TO ADDRESS
WRITE LAST
AFTER t WC
ADDRESS
BYTE TO
TO ANY
2AAA
5555
5555
ADDR.
DATA
5555
AA
BYTE/PAGE
LOAD ENABLED
2AAA
55
3855 FHD F17
5555
A0
t BLC MAX
t BLC MAX
7
t WPH2
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 X28C256
will automatically disable further writes unless another
command is issued to cancel it. If no further commands
are issued the X28C256 will be write protected during
power-down and after any subsequent power-up.
Note: Once initiated, the sequence of write operations
WRITES
should not be interrupted.
PAGE
BYTE
OK
OR
t WC
WRITE
PROTECTED
(V CC )
3855 FHD F16