CAT1161/2 (16K)
Supervisory Circuits with I2C Serial CMOS EEPROM, Precision Reset Controller and Watchdog Timer
FEATURES
■ Active high or low reset
■ Watchdog monitors SDA signal (CAT1161)
■ 400kHz I2C bus compatible
■ 2.7V to 6.0V operation
— Precision power supply voltage monitor
— 5V, 3.3V and 3V systems
— Five threshold voltage options
■ 1,000,000 Program/Erase cycles
■ Manual Reset
■ Low power CMOS technology
■ 16-Byte page write buffer
■ Built-in inadvertent write protection
— VCC lock out
■ 100 Year data retention
■ 8-pin DIP or 8-pin SOIC
— Write protect pin, WP
■ Commercial and industrial temperature ranges
DESCRIPTION
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 200
ms 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 is a complete memory and supervisory
solution for microcontroller-based systems. A serial
EEPROM memory (16K) with hardware memory write
protection, a system power supervisor with brown out
protectionandawatchdogtimerareintegratedtogether
inlowpowerCMOStechnology. Memoryinterfaceisvia
an I2C bus.
The 1.6-second watchdog circuit returns a system to a
known good state if a software or hardware glitch halts
or“hangs”thesystem.TheCAT1161watchdogmonitors
the SDA line, making an additional PC board trace
unnecessary. The lower cost CAT1162 does not have a
watchdog timer.
TheCAT1161/2memoryfeaturesa16-bytepage.Inaddition,
hardware data protection is provided by a write protect pin
WP and by a VCC sense circuit that prevents writes to
memory whenever VCC falls below the reset threshold or
until VCC reaches the reset threshold during power up.
Available packages include an 8-pin DIP and a surface
mount, 8-pin SO package.
The power supply monitor and reset circuit protects
memory and system controllers during power up/down
and against brownout conditions. Five reset threshold
BLOCK DIAGRAM
PIN CONFIGURATION
EXTERNAL LOAD
SENSE AMPS
SHIFT REGISTERS
D
OUT
ACK
V
DC
CC
V
CC
WORD ADDRESS
BUFFERS
COLUMN
DECODERS
RESET
GND
RESET
CAT1161/2
SCL
WP
GND
START/STOP
LOGIC
SDA
SDA
16K
EEPROM
XDEC
CONTROL
LOGIC
DC = Do not connect
WP
Part Dash Minimum Maximum
Number Threshold Threshold
DATA IN STORAGE
-45
-42
4.50
4.25
4.75
4.50
HIGH VOLTAGE/
TIMING CONTROL
RESET Controller
STATE COUNTERS
SCL
-30
-28
-25
3.00
2.85
2.55
3.15
3.00
2.70
Precision
SLAVE
ADDRESS
COMPARATORS
WATCHDOG
Only for
CAT1161
Vcc Monitor
RESET RESET
© 2002 by Catalyst Semiconductor, Inc.
Doc No. 3002, Rev. D
Characteristics subject to change without notice