Impala Linear Corporation
ILC1232
mP Supervisory Circuit
General Description
The ILC1232 is a multifunction circuit which monitors micro-
processor activity, external reset and power supplies in
microprocessor based systems. The circuit functions
include a watchdog timer, power supply monitor, micro-
processor reset, and manual pushbutton reset input.
The power supply line is monitored with a comparator and
an internal voltage reference. RST is forced low when an
out-of-tolerance condition exists and remains asserted for
at least 250ms after V
CC
rises above the threshold voltage
(4.5V or 4.75V). The RST pin will remain logic low with V
CC
as low as 1.4V.
The Watchdog input (ST) monitors mP activity and will
assert RST if no mP activity has occurred within the watch-
dog timeout period. The watchdog timeout period is selec-
table with nominal periods of 150, 600, or 1200 milliseconds.
Features
•
Power OK/Reset Time Delay, 250ms min.
•
Watchdog Timer, 150ms, 600ms, or 1.2s typical
•
Precision Supply Voltage Monitor, Select Between 5% or
10% of Supply Voltage
•
18µA Supply Current
•
Debounced External Reset Input
•
8-Pin SO Package
Applications
•
•
•
•
•
Computers
Controllers
Critical Microprocessor Power Monitoring
Intelligent Instruments
Portable Equipment
Ordering Information
Part
ILC1232N
ILC1232M
Package
8-Lead PDIP
8-Lead SOIC
Temp. Range
-40°C to +85°C
-40°C to +85°C
Typical Circuit
V
CC
Pin Package Configurations
Top View
V
CC
TD
V
CC
µ
P
ST
RST
TOL
GND
ETC1232N - 8 Lead Plastic DIP Package
ETC1232M - 8 Lead Plastic SOIC Package
PBRST
1
8
7
V
CC
ST
RST
RST
ILC1232
PBRST
I/O
RESET
TD
2
ILC1232
TOL
3
GND
4
6
5
Impala Linear Corporation
ILC1232 1.1
(408) 574-3939
www.impalalinear.com
Sept 1999
1
1
IMPALA [ Impala Linear Corporation ]
