X24257 Datasheet, PDF (9/19 Pages) Xicor Inc. – 400kHz 2-Wire Serial EEPROM with Block Lock

X24257 – Preliminary Information
the WEL bit and zeros to the other bits of the control BP2, BP1, BP0: Block Protect Bits (Nonvolatile)
register) or until the part powers up again. Writes to _{The Block Protect Bits, BP2, BP1 and BP0, determine}
WEL bit do not cause a high voltage write cycle, so the _{which blocks of the array are write protected. A write to}
device is ready for the next operation immediately after
the stop condition.
a protected block of memory is ignored. The block pro-
tect bits will prevent write operations to one of eight
segments of the array. The partitions are described in
Table 2.
ct ^{Table 2. Block Protect Bits}
BP2
BP1
BP0
u ⁰
0
0
0
0
1
d ⁰
1
0
0
1
1
1
0
0
o ₁
0
1
r ₁
1
0
P ¹
1
1
Protected Addresses
None
6000h - 7FFFh (8K bytes)
4000h - 7FFFh (16K bytes)
0000h - 7FFFh (32K bytes)
0000h - 003Fh (64 bytes)
0000h - 007Fh (128 bytes)
0000h - 00FFh (256 bytes)
0000h - 01FFh (512 bytes)
Array Lock
None
Upper 1/4 (Q4)
Upper 1/2 (Q3, Q4)
Full Array (All)
First Page (P1)
First 2 pgs (P2)
First 4 pgs (P4)
First 8 pgs (P8)
Figure 11. Block Protection Configuration
BP2–
e ^BP0
000
t ₀₀₁
e 010
l ₀₁₁
100
o ₁₀₁
s ¹¹⁰
Ob ¹¹¹
REV 1.1.1 10/15/00
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Characteristics subject to change without notice. 9 of 19