X24257 Datasheet, PDF (1/19 Pages) Xicor Inc. – 400kHz 2-Wire Serial EEPROM with Block Lock

Preliminary Information
256K
X24257
32K x 8 Bit
400kHz 2-Wire Serial EEPROM with Block Lock^™
FEATURES
• Save critical data with programmable block lock
protection
—Block lock (first page, first 2 pages, first 4
pages, first 8 pages, 1/4, 1/2, or all of EEPROM
array)
—Software write protection
—Programmable hardware write protect
• In circuit programmable ROM mode
• 400kHz 2-wire serial interface
—Schmitt trigger input noise suppression
—Output slope control for ground bounce noise
elimination
• Longer battery life with lower power
—Active read current less than 1µA
—Active write current less than 3µA
—Standby current less than 1µA
• 2.5V to 5.5V power supply
DESCRIPTION
The X24257 is a CMOS Serial EEPROM, internally
t ^{organized 32K x 8. The device features a serial inter-}
face and software protocol allowing operation on a
simple two wire bus.
c _{Three device select inputs (S0–S1) allow up to four}
devices to share a common two wire bus.
u _{A Write Protect Register at the highest address location,}
FFFFh, provides three write protection features: Software
d ^{Write Protect, Block Lock Protect, and Programmable}
Hardware Write Protect. The Software Write Protect
feature prevents any nonvolatile writes to the device
o ^{until the WEL bit in the Write Protect Register is set.}
The Block Lock Protection feature gives the user eight
r array block protect options, set by programming three
bits in the Write Protect Register. The Programmable
P^{Hardware Write Protect feature allows the user to}
• 64-byte page write mode
—Minimizes total write time per word
• Internally organized 32K x 8
• Bidirectional data transfer protocol
e • Self-timed write cycle
—Typical write cycle time of 5ms
t • High reliability
—Endurance: 100,000 cycles
—Data retention: 100 years
le ^{• 8-lead XBGA, 8-lead SOIC, 14-lead TSSOP}
install the device with WP tied to V_CC, write to and
Block Lock the desired portions of the memory array in
circuit, and then enable the In Circuit Programmable
ROM Mode by programming the WPEN bit HIGH in the
Write Protect Register. After this, the Block Locked
portions of the array, including the Write Protect Register
itself, are protected from being erased if WP is high.
Xicor EEPROMs are designed and tested for applica-
tions requiring extended endurance. Inherent data
retention is greater than 100 years.
o ^{BLOCK DIAGRAM}
Serial EEPROM Data
s^{and Address (SDA)}
Ob ^SCL
Command
Decode
and
Control
Logic
Block Lock and
Write Protect
Control Logic
Page
Decode
Logic
Data Register
Y Decode Logic
Serial EEPROM
Array
32K X 8
S₁
Device
Select
Write
Protect
S₀
Logic
Register
WP
Write Voltage
Control
REV 1.1.1 10/15/00
www.xicor.com
Characteristics subject to change without notice. 1 of 19