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LTC1503-1.8/LTC1503-2

High Efficiency Inductorless

Step-Down DC/DC Converters

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Input Voltage Range: 2.4V to 6V

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Fixed Output Voltages: 1.8V

±4%, 2V ±4%

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Output Current: Up to 100mA

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No Inductors

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Typical Efficiency 25% Higher than LDOs

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Low Operating Current: 25

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Low Shutdown Current: 5

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600kHz Switching Frequency

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Soft-Start Limits Inrush Current at Turn-On

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Short-Circuit and Overtemperature Protected

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Available in 8-Pin MSOP and SO Packages

The LTC

step-down DC/DC converters that produce a regulated

output from a 2.4V to 6V input. The parts use switched

capacitor fractional conversion to achieve high efficiency

over the entire input range. No inductors are required.

Internal circuitry controls the step-down conversion ratio

to optimize efficiency as the input voltage and load condi-

tions vary. Typical efficiency is 25% higher than that of a

low dropout (LDO) linear regulator.

Regulation is achieved by sensing the output voltage and

enabling the internal switching network as needed to

maintain a fixed output voltage. This method of regulation

enables the parts to achieve high efficiency at extremely

light loads. Low operating current (25

µA with no load, 5µA

in shutdown) and low external parts count (two 1

µF flying

capacitors and two 10

µF bypass capacitors) make the

LTC1503-1.8/LTC1503-2 ideally suited for space con-

strained battery-powered applications. The parts are fully

short-circuit and overtemperature protected.

The LTC1503-1.8/LTC1503-2 are available in 8-pin MSOP

and SO packages.

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

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Cellular Phones

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Handheld Computers

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Smart Card Readers

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Low Power DSP Supplies

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Portable Electronic Equipment

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Handheld Medical Instruments

Efficiency vs Input Voltage

Single Li-Ion to 2V DC/DC Converter

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

4

2

3

5

1

8

6

7

SHDN/SS

GND

LTC1503-2

1

µF

1503-1.8/2 TA01

1

µF

10

µF

1-CELL Li-Ion OR

3-CELL NiMH

10

µF

INPUT VOLTAGE (V)

2

60

80

6

1503-1.8/2 TA02

40

20

3

4

5

100

LTC1503-2

“IDEAL” LDO