LTC3646/LTC3646-1

1

36461fc

For more information www.linear.com/LTC3646

TYPICAL APPLICATION

FEATURES

DESCRIPTION

40V, 1A Synchronous

Step-Down Converter

The LTC®3646 is a high efficiency, step-down DC/DC

converter with internal high side and synchronous power

FETs. It draws only 140µA typical DC supply current in

Burst Mode operation at no load while maintaining output

voltage regulation.

The LTC3646 can supply up to a 1A load, and its combina-

tion of Burst Mode operation, integrated power switches

and low quiescent current provides high efficiency over a

broad range of load currents. Alternatively, it can be used

inforcedcontinuousmodeforripplesensitiveapplications.

The LTC3646 has a wide 4.0V to 40V input range and its

patented controlled on-time architecture and 0.6V refer-

ence voltage allow for large step-down ratios without

the risk of output overvoltage. The frequency may be set

between 200kHz and 3.0MHz with a program resistor or

synchronized to an external clock.

The internal soft-start, short-circuit protection and volt-

age rating make the LTC3646 a robust part ideal for high

voltage applications.

Efficiency Curve

APPLICATIONS

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Wide Input Voltage Range: 4.0V to 40V

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1A Guaranteed Output Current

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High Efficiency: Up to 95%

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Wide Output Voltage Range

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LTC3646: 2.0V to 30V

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LTC3646-1: 0.6V to 15V

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±1% Accurate Reference Voltage

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Internal or External Compensation

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Switching Frequency Adjustable and Synchronizable:

200kHz to 3MHz

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Selectable High Efficiency Burst Mode® Operation or

Forced Continuous Mode

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14 Lead 3mm × 4mm DFN or Thermally Enhanced

16-Lead MSOP Packages

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Point of Load Power Supplies

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Intermediate Bus Power

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Automotive Applications

L

, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks

and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners. Protected by U.S. Patents, including 6580258, 5481178,

5994885, 6304066, 5847554, 6476589, 6774611.

LOAD CURRENT (A)

0.001

40

60

1

3646 TA01b

20

0

0.1

0.01

100

30

50

10

70

80

90

0.4

0.2

0.8

0

1.0

0.6

VOUT = 3.3V

VOUT = 5V

VOUT = 3.3V

VOUT = 5V

VIN = 12V

f = 1MHz

PVIN

SVIN

RUN

INTVCC

MODE/SYNC

ITH

RT

EXTVCC

BOOST

SW

VON

VFB

+ –

SWITCH

CONTROL

LTC3646

3.3µH

SGND

4.7µF

PGND

0.1µF

412k

10µF

0.6V

56.2k

3646 TA01a

15µF

VOUT

5V

1A

VIN

40V MAX