CAT24C161/162 (16K), CAT24C081/082 (8K)
CAT24C041/042 (4K), CAT24C021/022 (2K)
Supervisory Circuits with I2C Serial CMOS EEPROM, Precision Reset Controller and Watchdog Timer
■ Active high or low reset
FEATURES
— Precision power supply voltage monitor
— 5V, 3.3V and 3V systems
■ Watchdog monitors SDA for the CAT24CXX1
■ 400 KHz I2C bus compatible
■ 2.7 to 6.0 Volt operation
— Five threshold voltage options
■ 1,000,000 Program/Erase cycles
■ 100 Year data retention
■ Low power CMOS technology
■ 16-Byte page write buffer
■ Built-in inadvertent write protection
— VCC lock out
■ 8-pin DIP or 8-pin SOIC
■ Commercial, industrial and automotive
temperature ranges
— Write protect pin, WP
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.
DESCRIPTION
TheCAT25Cxx1isacompletememoryandsupervisory
solution for microcontroller-based systems. A serial
EEPROM memory (2/4/8/16K) 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 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” the system. The CAT24Cxx1 watchdog
monitors the SDA line, making an additional PC board
trace unnecessary. The lower cost CAT24Cxx2 does
not have a watchdog timer.
TheCAT24Cxxxmemoryfeaturesa16-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.
The power supply monitor and reset circuit protects
memory and system controllers during power up/down
Available packages include an 8-pin DIP and a surface
mount, 8-pin SO package.
BLOCK DIAGRAM
PIN CONFIGURATION
EXTERNAL LOAD
SENSE AMPS
SHIFT REGISTERS
D
OUT
V
ACK
DC
RESET
WP
CC
V
CC
CAT
24CXX1/2
RESET
WORD ADDRESS
BUFFERS
COLUMN
DECODERS
GND
SCL
SDA
START/STOP
LOGIC
SDA
V
SS
E2PROM
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
CAT24C161
Vcc Monitor
24C1601 BLOCK
RESET RESET
© 2001 by Catalyst Semiconductor, Inc.
Doc No. 3000, Rev. A
Characteristics subject to change without notice