LP3985

Micropower, 150mA Low-Noise Ultra Low-Dropout CMOS

Voltage Regulator

General Description

The LP3985 is designed for portable and wireless applica-

tions with demanding performance and space requirements.

high-quality tantalum output capacitor. The micro SMD re-

quires the smallest possible PC board area - the total appli-

cation circuit area can be less than 2.0mm x 2.5mm, a

fraction of a 1206 case size.

The LP3985’s performance is optimized for battery powered

systems to deliver ultra low noise, extremely low dropout

voltage and low quiescent current. Regulator ground current

increases only slightly in dropout, further prolonging the

battery life.

An optional external bypass capacitor reduces the output

noise without slowing down the load transient response.

Fast start-up time is achieved by utilizing an internal

power-on circuit that actively pre-charges the bypass capaci-

tor.

Power supply rejection is better than 50 dB at low frequen-

cies and starts to roll off at 1kHz. High power supply rejection

is maintained down to low input voltage levels common to

battery operated circuits.

The device is ideal for mobile phone and similar battery

powered wireless applications. It provides up to 150 mA,

from a 2.5V to 6V input. The LP3985 consumes less than

1.5µA in disable mode and has fast turn-on time less than

200µs.

The LP3985 is available in a 5 bump small bump micro SMD,

a 5 bump large bump micro SMD, a 5 bump thin micro SMD

and a 5 pin SOT-23 package. Performance is specified for

−40˚C to +125˚C temperature range and is available in 2.5V,

2.6V, 2.7V, 2.8V, 2.85V, 2.9V, 3.0V. 3.1V, 3.2V, 3.3V, 4.7V,

4.8V and 5.0V output voltages. For other output voltage

options between 2.5V to 5.0V or for a dual LP3985, please

contact National Semiconductor sales office.

Key Specifications

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2.5 to 6.0V input range

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150mA guaranteed output

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≤1.5µA quiescent current when shut down

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Fast Turn-On time: 200 µs (typ.)

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100mV maximum dropout with 150mA load

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30µVrms output noise (typ) over 10Hz to 100kHz

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

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2.5V, 2.6V, 2.7V, 2.8V, 2.85V, 2.9V, 3.0V, 3.1V, 3.2V,

3.3V, 4.7V, 4.8V and 5.0V outputs standard

Features

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Miniature 5-I/O micro SMD and SOT-23-5 package

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Logic controlled enable

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Stable with ceramic and high quality tantalum capacitors

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Fast turn-on

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Thermal shutdown and short-circuit current limit

Applications

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CDMA cellular handsets

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Wideband CDMA cellular handsets

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GSM cellular handsets

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Portable information appliances

Typical Application Circuit

10136402

Note: Pin Numbers in parenthesis indicate micro SMD package.

* Optional Noise Reduction Capacitor.

June 2003

© 2003 National Semiconductor Corporation

DS101364

www.national.com