LT1073

1

APPLICATIO S

DESCRIPTIO

FEATURES

The LT

The device requires only three external components to

deliver a fixed output of 5V or 12V. The very low minimum

supply voltage of 1V allows the use of the LT1073 in

applications where the primary power source is a single

cell. An on-chip auxiliary gain block can function as a low-

battery detector or linear post-regulator.

Average current drain of the LT1073-5 used as shown in

the Typical Application circuit below is just 135

µA un-

loaded, making it ideal for applications where long battery

life is important. The circuit shown can deliver 5V at 40mA

from an input as low as 1.25V and 5V at 10mA from a 1V

input.

The device can easily be configured as a step-up or step-

down converter, although for most step-down applica-

tions or input sources greater than 3V, the LT1173 is

recommended. Switch current limiting is user-adjustable

by adding a single external resistor. Unique reverse-

battery protection circuitry limits reverse current to safe,

nondestructive levels at reverse supply voltages up to

1.6V.

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Pagers

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Cameras

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Single-Cell to 5V Converters

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Battery Backup Supplies

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Laptop and Palmtop Computers

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Cellular Telephones

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Portable Instruments

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4mA to 20mA Loop Powered Instruments

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Hand-Held Inventory Computers

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Battery-Powered

α, β, and γ Particle Detectors

, LTC and LT are registered trademarks of Linear Technology Corporation.

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No Design Required

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Operates at Supply Voltages from 1V to 30V

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Consumes Only 95

µA Supply Current

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Works in Step-Up or Step-Down Mode

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Only Three External Off-the-Shelf Components

Required

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Low-Battery Detector Comparator On-Chip

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User-Adjustable Current Limit

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Internal 1A Power Switch

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Fixed or Adjustable Output Voltage Versions

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Space-Saving 8-Pin PDIP or SO-8 Package

Micropower

DC/DC Converter

Adjustable and Fixed 5V, 12V

+

1N5818

5V

40mA

100

µF

SANYO

0S-CON

1073 TA01

LT1073-5

SW1

SENSE

SW2

GND

1

2

3

4

5

8

1.5V

AA CELL*

CADDELL-BURNS

7300-12

82

µH

OPERATES WITH CELL VOLTAGE

≥1V

ADD 10

µF DECOUPLING CAPACITOR IF

BATTERY IS MORE THAN 2" AWAY FROM LT1073

*

LOAD CURRENT (mA)

1

1000

100

10

1

10

100

LT1073 TA02

L = 180

µH

L = 82

µH

Single-Cell to 5V Converter

Single Alkaline “AA” Cell Operating

Hours vs DC Load Current