A
PPLICATION
N
OTES
A V A I L A B L E
AN11
X25043/45
• AN21
4K
X25043/45
Programmable Watchdog Supervisory E
2
PROM
DESCRIPTION
512 x 8 Bit
FEATURES
•
•
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•
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Programmable Watchdog Timer
Low V
CC
Detection
Reset Signal Valid to V
CC
= 1V
1MHz Clock Rate
512 X 8 Bits Serial E
2
PROM
—4 Byte Page Mode
Low Power CMOS
—50
µ
A Standby Current
—3mA Active Current
2.7V To 5.5V Power Supply
Block Lock
TM
—Protect 1/4, 1/2 or all of E
2
PROM Array
Built-in Inadvertent Write Protection
—Power-Up/Power-Down protection circuitry
—Write Latch
—Write Protect Pin
High Reliability
—Endurance: 100,000 cycles per byte
—Data Retention: 100 Years
—ESD protection: 2000V on all pins
Available Packages
—8-Lead PDlP
—8-Lead SOIC
—14-Lead TSSOP
X25043 = Active LOW
RESET
X25045 = Active HIGH RESET
The X25043/45 combines three popular functions,
Watchdog Timer, Voltage Supervision, and E
2
PROM in
a single package. This combination lowers the system
cost and reduces the board space requirements.
The Watchdog Timer provides an independent protec-
tion system for microcontrollers. During a system failure,
the X25043/45 watchdog will respond with a
RESET/
RESET signal after a selectable time-out interval. The
user selects the interval from three preset values. Once
selected, the interval does not change, even after cy-
cling the power.
The system is protected from low voltage conditions by
the X25043/45 low V
CC
detection circuits. When V
CC
drops below the minimum V
CC
trip point, the system is
reset. Reset is asserted until V
CC
returns and stabilizes.
The memory portion of the X25043/45 is a CMOS 4096-
bit serial E
2
PROM, internally organized as 512 X 8. The
X25043/45 features a Serial Peripheral Interface (SPI)
and software protocol allowing operation on a simple
three-wire bus.
The X25043/45 utilizes Xicor’s proprietary Direct Write™
cell, providing a minimum endurance of 100,000 cycles
per byte and a minimum data retention of 100 years.
DIE PHOTOGRAPH
RESET
CONTROL
LOGIC
PROGRAMMABLE
VOLTAGE
SENSOR
SERIAL
INTERFACE
LOGIC
2
4K BITS E
2
PROM
W
A T
T I
C M
H E
D R
O
G
HIGH VOLTAGE GENERATOR
HIGH VOLTAGE GENERATOR
AND
AND
CONTROL
CONTROL
Direct Write™ is a trademark of Xicor, Inc.
©Xicor, Inc. 1994, 1995, 1996 Patents Pending
3844-6.5 5/9/96 T4/C2/D2 NS
3844 ILL F01
Characteristics subject to change without notice
1
XICOR [ XICOR INC. ]
