1

LT3430

sn3430 3430is

High Voltage, 3A,

200kHz Step-Down

Switching Regulator

August 2002

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Wide Input Range: 5.5V to 60V

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3A Peak Switch Current

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Small Thermally Enhanced 16-Pin TSSOP Package

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Constant 200kHz Switching Frequency

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Saturating Switch Design: 0.1

Ω

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Peak Switch Current Maintained Over

Full Duty Cycle Range

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Effective Supply Current: 2.5mA

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Shutdown Current: 30

µA

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1.2V Feedback Reference Voltage

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Easily Synchronizable

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Cycle-by-Cycle Current Limiting

The LT

lator that accepts input voltages up to 60V. A high efficiency

3A, 0.1

Ωswitchisincludedonthediealongwithallthenec-

essary oscillator, control and logic circuitry. A current mode

architecture provides fast transient response and excellent

loop stability.

Special design techniques and a new high voltage process

achieve high efficiency over a wide input range. Efficiency

is maintained over a wide output current range by using the

output to bias the circuitry and by utilizing a supply boost

capacitor to saturate the power switch. Patented circuitry

maintains peak switch current over the full duty cycle range.

A shutdown pin reduces supply current to 30

µAandaSYNC

pin can be externally synchronized from 228kHz to 700kHz

with a logic level input.

The LT3430 is available in a thermally enhanced 16-pin

TSSOP package.

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Industrial and Automotive Power Supplies

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Portable Computers

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Battery Chargers

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Distributed Power Systems

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

5V, 2A Buck Converter

Efficiency vs Load Current

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

BOOST

6

2, 5

10

12

30BQ060

15.4k

5V

2A

3, 4

15

14

11

220pF

0.022

µF

*

†

FOR INPUT VOLTAGES BELOW 7.5V, SOME RESTRICTIONS MAY APPLY

UNITED CHEMI-CON

1, 8, 9, 16

LT3430

SHDN

SYNC

SW

BIAS

FB

GND

0.68

µF

100

µF 10V

SOLID

TANTALUM

22

µH

MMSD914TI

4.99k

3430 TA01

4.7

µF 100V

CERAMIC

†

ON

OFF

5.5V*

TO 60V

+

3.3k

LOAD CURRENT (A)

0

80

90

100

2.0

3430 TA02

70

60

50

0.5

1.0

1.5

2.5

L = 27

µH

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

Final Electrical Specifications