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
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
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 5 V, 3.3 V and 3 V
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 pushbutton 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 VCCsense circuit that prevents writes to memory whenever VCCfalls
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.

Features
• Watchdog Monitors SDA Signal (CAT1161)
• 400 kHz I2C Bus Compatible
• 2.7 V to 6 V Operation
• Low Power CMOS Technology
• 16−Byte Page Write Buffer
• Built−in Inadvertent Write Protection
♦ VCC Lock Out
♦ Write Protection Pin, WP
• Active High or Low Reset
♦ Precision Power Supply Voltage Monitor
♦ 5 V, 3.3 V and 3 V Systems
♦ Five Threshold Voltage Options
• 1,000,000 Program/Erase Cycles
• Manual Reset
• 100 Year Data Retention
• 8−Pin DIP or 8−Pin SOIC
• Commercial and Industrial Temperature Ranges
• These Devices are Pb−Free, Halogen Free/BFR Free
and are RoHS Compliant