LM2621

Low Input Voltage, Step-Up DC-DC Converter

General Description

The LM2621 is a high efficiency, step-up DC-DC switching

regulator for battery-powered and low input voltage systems.

It accepts an input voltage between 1.2V and 14V and con-

verts it into a regulated output voltage. The output voltage

can be adjusted between 1.24V and 14V. It has an internal

0.17

Ω N-Channel MOSFET power switch. Efficiencies up to

90% are achievable using the LM2621.

The high switching frequency (adjustable up to 2MHz) of the

LM2621 allows for tiny surface mount inductors and capaci-

tors. Because of the unique constant-duty-cycle gated oscil-

lator topology very high efficiencies are realized over a wide

load range. The supply current is reduced to 80µA because

of the BiCMOS process technology. In the shutdown mode,

the supply current is less than 2.5µA.

The LM2621 is available in a Mini-SO-8 package. This pack-

age uses half the board area of a standard 8-pin SO and has

a height of just 1.09 mm.

Features

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Small Mini-SO8 Package (Half the Footprint of Standard

8-Pin SO Package)

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1.09 mm Package Height

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Up to 2 MHz Switching Frequency

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1.2V to 14V Input Voltage

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1.24V - 14V Adjustable Output Voltage

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Up to 1A Load Current

n

0.17

Ω Internal MOSFET

n

Up to 90% Regulator Efficiency

n

80 µA Typical Operating Current

2.5µA Guaranteed Supply Current In Shutdown

Applications

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PDAs, Cellular Phones

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2-Cell and 3-Cell Battery-Operated Equipment

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PCMCIA Cards, Memory Cards

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Flash Memory Programming

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TFT/LCD Applications

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3.3V to 5.0V Conversion

n

GPS Devices

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Two-Way Pagers

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Palmtop Computers

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Hand-Held Instruments

Typical Application Circuit

DS100934-12

February 2000

© 2000 National Semiconductor Corporation

DS100934

www.national.com