LP3873/LP3876

3A Fast Ultra Low Dropout Linear Regulators

General Description

The LP3873/LP3876 series of fast ultra low-dropout linear

regulators operate from a +2.5V to +7.0V input supply. Wide

range of preset output voltage options are available. These

ultra low dropout linear regulators respond very quickly to

step changes in load, which makes them suitable for low

voltage microprocessor applications. The LP3873/LP3876

are developed on a CMOS process which allows low quies-

cent current operation independent of output load current.

This CMOS process also allows the LP3873/LP3876 to op-

erate under extremely low dropout conditions.

Dropout Voltage: Ultra low dropout voltage; typically 80mV

at 300mA load current and 800mV at 3A load current.

Ground Pin Current: Typically 6mA at 3A load current.

Shutdown Mode: Typically 1µA quiescent current when the

shutdown pin is pulled low.

Error Flag: Error flag goes low when the output voltage

drops 10% below nominal value.

SENSE: Sense pin improves regulation at remote loads.

Precision Output Voltage: Multiple output voltage options

are available ranging from 1.8V to 5.0V with a guaranteed

conditions (varying line, load, and temperature).

Features

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Ultra low dropout voltage

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Low ground pin current

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Load regulation of 0.08%

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1µA quiescent current in shutdown mode

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Guaranteed output current of 3A DC

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Available in TO-263 and TO-220 packages

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Error flag indicates output status

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Sense option improves load regulation

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Minimum output capacitor requirements

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Overtemperature/overcurrent protection

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−40˚C to +125˚C junction temperature range

Applications

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Microprocessor power supplies

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GTL, GTL+, BTL, and SSTL bus terminators

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Power supplies for DSPs

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SCSI terminator

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Post regulators

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High efficiency linear regulators

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Battery chargers

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Other battery powered applications

Typical Application Circuits

20060501

*SD and ERROR pins must be pulled high through a 10k

Ω pull-up resistor. Connect the ERROR pin to ground if this function is not used. See application hints

for more information.

September 2006

© 2006 National Semiconductor Corporation

DS200605

www.national.com