LM3712/LM3713 Microprocessor Supervisory Circuits with Separate Watchdog Timer Output,
Power Fail Input and Manual Reset
July 2002
LM3712/LM3713
Microprocessor Supervisory Circuits with Separate
Watchdog Timer Output, Power Fail Input and Manual
Reset
General Description
The LM3712/LM3713 series of microprocessor supervisory
circuits provide the maximum flexibility for monitoring power
supplies and battery controlled functions in systems without
backup batteries. The LM3712/LM3713 series are available
in a 9-bump micro SMD package.
Built-in features include the following:
Reset: Reset is asserted during power-up, power-down, and
brownout conditions. RESET is guaranteed down to V
CC
of
1.0V.
Manual Reset Input: An input that asserts reset when pulled
low.
Power-Fail Input: A 1.225V threshold detector for power fail
warning, or to monitor a power supply other than V
CC
.
Watchdog Timer: The WDI (Watchdog Input) monitors one of
the 碌P鈥檚 output lines for activity. If no output transition occurs
during the watchdog timeout period, the watchdog output
(WDO) pulls low.
Features
n
Standard Reset Threshold voltage: 3.08V
n
Custom Reset Threshold voltages: For other voltages
between 2.2V and 5.0V in 10mV increments, contact
National Semiconductor Corp.
n
No external components required
n
Manual-Reset input
n
RESET (LM3712) or RESET (LM3713) outputs
n
Precision supply voltage monitor
n
Factory programmable Reset and Watchdog Timeout
Delays
n
Separate Watchdog output
n
Separate Power Fail comparator
n
Available in micro SMD package for minimum footprint
n
鹵
0.5% Reset threshold accuracy at room temperature
n
鹵
2% Reset threshold accuracy over temperature
extremes
n
Reset assertion down to 1V V
CC
(RESET option only)
n
28 碌A(chǔ) V
CC
supply current
Applications
n
n
n
n
Embedded Controllers and Processors
Intelligent Instruments
Automotive Systems
Critical 碌P Power Monitoring
Typical Application
20011903
漏 2002 National Semiconductor Corporation
DS200119
www.national.com