MIC1232 Datasheet, PDF (1/8 Pages) Micrel Semiconductor – μP Supervisory Circuit

MIC1232 µP Supervisory Circuit
MIC1232
µP Supervisory Circuit
Description
The MIC1232 is a multifunction circuit which monitors
microprocessor activity, external reset and power
supplies in microprocessor based systems. The circuit
functions include a watchdog timer, power supply
monitor, microprocessor 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 VCC rises above the
threshold voltage (4.5V or 4.75V). The RST pin will
remain logic low with VCC as low as 1.4V.
The Watchdog input (ST) monitors µP activity and will
assert RST if no µP activity has occurred within the
watchdog timeout period. The watchdog timeout period
is selectable with nominal periods of 150, 600, or 1200
milliseconds.
Typical Applications
· ^{Automotive Systems}
· ^{Intelligent Instruments}
· ^{Critical Microprocessor Power Monitoring}
· ^{Battery Powered Computers}
· ^Controllers
Pin Configuration
Top View
PBRST ¹
TD ²
TOL 3
GND 4
MIC1232
8 _VCC
7 _ST
6 RST
5 RST
MIC1232N - 8 Lead Plastic DIP Package
MIC1232M - 8 Lead Plastic SOIC Package
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
· ^{Available in 8-pin Surface Mount (SO)}
· ^{Debounced External Reset Input}
· ^{Low Supply Current, < 18µA Typ.}
Ordering Information
Part
MIC1232N
MIC1232M
Package
8-Lead PDIP
8-Lead SOIC
Temp. Range
-40°C to +85°C
-40°C to +85°C
Typical Operating Circuit
VCC
VCC
TD
MIC1232
PBRST
ST
RST
TOL GND
VCC
µP
I/O
RESET
1