CAT1161/2 (16K)
Supervisory Circuits with I
2
C Serial CMOS EEPROM, Precision Reset Controller and Watchdog Timer
FEATURES
s
Watchdog monitors SDA signal (CAT1161)
s
400kHz I
2
C bus compatible
s
2.7V to 6.0V operation
s
Low power CMOS technology
s
16-Byte page write buffer
s
Built-in inadvertent write protection
s
Active high or low reset
— Precision power supply voltage monitor
— 5V, 3.3V and 3V systems
— Five threshold voltage options
s
1,000,000 Program/Erase cycles
s
Manual Reset
s
100 Year data retention
s
8-pin DIP or 8-pin SOIC
s
Commercial and industrial temperature ranges
— V
CC
lock out
— Write protect pin, WP
DESCRIPTION
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
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 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 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.
PIN CONFIGURATION
DC
RESET
WP
GND
VCC
BLOCK DIAGRAM
EXTERNAL LOAD
DOUT
ACK
VCC
GND
WORD ADDRESS
BUFFERS
COLUMN
DECODERS
SENSE AMPS
SHIFT REGISTERS
CAT1161/2
RESET
SCL
SDA
SDA
START/STOP
LOGIC
16K
EEPROM
XDEC
DC = Do not connect
WP
CONTROL
LOGIC
Part Dash Minimum
Number Threshold
-45
-42
-30
-28
-25
4.50
4.25
3.00
2.85
2.55
Maximum
Threshold
4.75
4.50
RESET Controller
DATA IN STORAGE
HIGH VOLTAGE/
TIMING CONTROL
STATE COUNTERS
SLAVE
ADDRESS
COMPARATORS
3.15
3.00
2.70
Only for
CAT1161
WATCHDOG
SCL
Precision
Vcc Monitor
RESET
RESET
© 2002 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Doc No. 3002, Rev. D
CATALYST [ CATALYST SEMICONDUCTOR ]
