LP38843

3A Ultra Low Dropout Linear Regulators

Stable with Ceramic Output Capacitors

General Description

The LP38843 is a high-current, fast-response regulator

which can maintain output voltage regulation with minimum

input to output voltage drop. Fabricated on a CMOS process,

the device operates from two input voltages: Vbias provides

voltage to drive the gate of the N-MOS power transistor,

while Vin is the input voltage which supplies power to the

load. The use of an external bias rail allows the part to

operate from ultra low Vin voltages. Unlike bipolar regula-

tors, the CMOS architecture consumes extremely low quies-

cent current at any output load current. The use of an

N-MOS power transistor results in wide bandwidth, yet mini-

mum external capacitance is required to maintain loop sta-

bility.

The fast transient response of these devices makes them

suitable for use in powering DSP, Microcontroller Core volt-

ages and Switch Mode Power Supply post regulators. The

parts are available in TO-220 and TO-263 packages.

Quiescent Current: 30 mA (typ) at full load.

Shutdown Current: 30 nA (typ) when S/D pin is low.

Precision Output Voltage: 1.5% room temperature accu-

racy.

Features

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Ideal for conversion from 1.8V or 1.5V inputs

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Designed for use with low ESR ceramic capacitors

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0.8V, 1.2V and 1.5V standard voltages available

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1.5% initial output accuracy

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Load regulation of 0.1%/A (typical)

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30nA quiescent current in shutdown (typical)

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Low ground pin current at all loads

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Over temperature/over current protection

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Available in 5 lead TO220 and TO263 packages

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

Applications

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ASIC Power Supplies In:

- Desktops, Notebooks, and Graphics Cards, Servers

- Gaming Set Top Boxes, Printers and Copiers

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Server Core and I/O Supplies

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DSP and FPGA Power Supplies

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SMPS Post-Regulator

Typical Application Circuit

20102901

* Minimum value required if Tantalum capacitor is used (see Application Hints).

December 2004

© 2004 National Semiconductor Corporation

DS201029

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