CAT1161, CAT1162
Supervisory Circuits with I
2
C Serial CMOS EEPROM,
Precision Reset Controller and Watchdog Timer (16K)
FEATURES
Watchdog monitors SDA signal (CAT1161)
400kHz I
2
C bus compatible
2.7V to 6.0V operation
Low power CMOS technology
16-Byte page write buffer
Built-in inadvertent write protection
—
—
—
—
—
V
CC
lock out
Write protect pin, WP
Precision power supply voltage monitor
5V, 3.3V and 3V systems
Five threshold voltage options
brown out protection and a watchdog timer are
integrated together in low power CMOS technology.
Memory interface is via an I
2
C bus.
The 1.6-second watchdog circuit returns a system to a
known good state if a software or hardware glitch
halts or “hangs” the system. The CAT1161 watchdog
monitors the SDA line, making an additional PC board
trace unnecessary. The lower cost CAT1162 does not
have a watchdog timer.
The power supply monitor and reset circuit protects
memory and system controllers during power up/down
and against brownout conditions. Five reset threshold
voltages support 5V, 3.3V and 3V systems. If power
supply voltages are out of tolerance reset signals
become active, preventing the system microcontroller,
ASIC or peripherals from operating. Reset signals
become inactive typically 200ms after the supply
voltage exceeds the reset threshold level. With both
active high and low reset signals, interface to
microcontrollers and other ICs is simple. In addition, a
reset pin can be used as a debounced input for push-
button manual reset capability.
The CAT1161/2 memory features a 16-byte page. In
addition, hardware data protection is provided by a
write protect pin WP and by a V
CC
sense circuit that
prevents writes to memory whenever V
CC
falls below
the reset threshold or until V
CC
reaches the reset
threshold during power up.
Available packages include an 8-pin DIP and a
surface mount, 8-pin SO package.
Active high or low reset
1,000,000 Program/Erase cycles
Manual Reset
100 Year data retention
8-pin DIP or 8-pin SOIC
Commercial and industrial temperature ranges
DESCRIPTION
The CAT1161/2 is a complete memory and supervi-
sory solution for microcontroller-based systems. A se-
rial EEPROM memory (16K) with hardware memory
write protection, a system power supervisor with
PIN CONFIGURATION
PDIP 8 Lead
SOIC 8 Lead
DC
¯¯¯¯¯¯
RESET
WP
GND
1
2
3
4
CAT1161
CAT1162
8
7
6
5
V
CC
RESET
SCL
SDA
PIN FUNCTIONS
Pin Name
DC
¯¯¯¯¯¯
RESET
WP
GND
SDA
SCL
RESET
V
CC
Function
Do not Connect
Active Low Reset I/O
Write Protect
Ground
Serial Data/Address
Clock Input
Active High Reset I/O
Power Supply
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. MD-3002 Rev. G
CATALYST [ CATALYST SEMICONDUCTOR ]
