1

LT3433

3433ia

High Voltage

Step-Up/Step-Down

DC/DC Converter

September 2003

s

Automatic Step-Up and Step-Down Conversion

s

Uses a Single Inductor

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Wide 4V to 60V Input Voltage Range

s

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Dual Internal 500mA Switches

s

100

µA No-Load Quiescent Current

s

Low Current Shutdown

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±1% Output Voltage Accuracy

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200kHz Operating Frequency

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Boosted Supply Pin to Saturate High Side Switch

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Frequency Foldback Protection

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Current Limit Foldback Protection

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Current Limit Unaffected by Duty Cycle

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16-lead Thermally Enhanced TSSOP Package

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12V Automotive Systems

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Wall Adapter Powered Systems

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Battery Power Voltage Buffering

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

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

Burst Mode is a registered trademark of Linear Technology Corporation.

The LT

switching regulator that provides both step-up and step-

down regulation using a single inductor. The IC operates

over a 4V to 60V input voltage range making it suitable for

use in various wide input voltage range applications such

as automotive electronics that must withstand both load

dump and cold crank conditions.

Internal control circuitry monitors system conditions and

converts from single switch buck operation to dual switch

bridged operation when required, seamlessly changing

between step-down and step-up voltage conversion.

Optional Burst Mode

cent current to 100

µA and maintains high efficiencies with

light loads.

Current limit foldback and frequency foldback help pre-

vent inductor current runaway during start-up. Program-

mable soft-start helps prevent output overshoot at start-up.

The LT3433 is available in a 16-lead thermally enhanced

TSSOP package.

SW_H

BURST_EN

SW_L

PWRGND

SHDN

SS

SGND

LT3433

1N4148

0.1

µF

68k

100k

0.5%

305k

0.5%

1nF100pF

2.2

µF

4V TO 60V

0.01

µF

3433 TA01

0.1

µF

1N4148

L1

100

µH

CoEv DU1352-101M

B120A

47

µF

5V

4V

8.5V

+

B160A

4V to 60V to 5V DC/DC Converter

with Burst Mode Operation

Final Electrical Specifications

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.

OUTPUT CURRENT (mA)

40

60

80

90

0.1

10

100

1000

3433 TA01b

20

1

70

50

30

Efficiency

0

0

100

200

300

400

500

10

20

30

40

3433 TA01c

50

60

BRIDGED

BUCK

Maximum Output