LM3704/LM3705

Microprocessor Supervisory Circuits with Power Fail

Input, Low Line Output and Manual Reset

General Description

The LM3704/LM3705 series of microprocessor supervisory

circuits provide the maximum flexibility for monitoring power

supplies and battery controlled functions in systems without

backup batteries. The LM3704/LM3705 series are available

in MSOP-10 and 9-bump micro SMD packages.

Built-in features include the following:

Reset: Reset is asserted during power-up, power-down, and

brownout conditions. RESET is guaranteed down to V

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

Low Line Output: This early power failure warning indicator

goes low when the supply voltage drops to a value which is

2% higher than the reset threshold voltage.

Features

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Standard Reset Threshold voltage: 3.08V

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Custom Reset Threshold voltages: For other voltages

between 2.2V and 5.0V in 10mV increments, contact

National Semiconductor Corp.

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No external components required

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Manual-Reset input

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RESET (LM3704) or RESET (LM3705) outputs

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Precision supply voltage monitor

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Factory programmable Reset Timeout Delay

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Separate Power Fail comparator

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Available in micro SMD package for minimum footprint

0.5% Reset threshold accuracy at room temperature

2% Reset threshold accuracy over temperature

extremes

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Reset assertion down to 1V V

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28 µA V

Applications

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Embedded Controllers and Processors

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Intelligent Instruments

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Automotive Systems

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Critical µP Power Monitoring

Typical Application

10136903

July 2002

© 2002 National Semiconductor Corporation

DS101369

www.national.com