MIC2755
Micrel, Inc.
MIC1232
µP Supervisory Circuit
General Description
The MIC1232 is a multifunction circuit which monitors mi-
croprocessor activity, external reset and power supplies in
microprocessor based systems. The circuit functions include
a watchdog time, 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 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 µP activity and will as-
sert /RST if no µP activity has occurred with in the watchdog
timeout period. The watchdog timeout period is selectable
with nominal period of 150, 600, 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
• Available in 8-pin surface mount (SO)
• Debounced External reset input
• Low supply current, <18µA typical
Applications
•
•
•
•
•
Automotive systems
Intelligent systems
Critical microprocessor power monitoring
Battery powered computers
Controllers
Ordering Information
Part Number
Standard
MIC1232N
MIC1232M
Pb-Free
MIC1232NY
MIC1232MY
Temperature Range
–40ºC to +85ºC
–40ºC to +85ºC
Package
8-Pin PDIP
8-Pin SOIC
Typical Application
VCC
VCC
TD
ST
RST
VCC
µP
MIC1232
PBRST
I/O
RESET
TOL GND
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
January 2006
1
MIC1232
MICREL [ MICREL SEMICONDUCTOR ]
