LTC3411A

1

3411afa

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

1.25A, 4MHz, Synchronous

Step-Down DC/DC Converter

The LTC

step-down DC/DC converter. Intended for medium power

applications, it operates from a 2.5V to 5.5V input voltage

range and has a user configurable operating frequency

up to 4MHz, allowing the use of tiny, low cost capacitors

and inductors 1mm or less in height. The output voltage is

adjustable from 0.8V to 5.5V. Internal synchronous power

switches provide high efficiency. The LTC3411A’s current

mode architecture and external compensation allow the

transient response to be optimized over a wide range of

loads and output capacitors.

The LTC3411A can be configured for automatic power

charge losses when the load current drops below the level

required for continuous operation. For reduced noise and

RF interference, the SYNC/MODE pin can be configured to

skip pulses or provide forced continuous operation.

To further maximize battery life, the P-channel MOSFET

is turned on continuously in dropout (100% duty cycle).

In shutdown, the device draws <1μA.

Step-Down 2.5V/1.25A Regulator

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Uses Tiny Capacitors and Inductor

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High Frequency Operation: Up to 4MHz

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High Efficiency: Up to 96%

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®

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Stable with Ceramic Capacitors

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Current Mode Operation for Excellent Line

and Load Transient Response

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Short-Circuit Protected

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Low Dropout Operation: 100% Duty Cycle

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Output Voltages from 0.8V to 5V

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Synchronizable to External Clock

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Supports Pre-Biased Outputs

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Small 10-Lead 3mm × 3mm DFN or MSOP Package

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Notebook Computers

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Digital Cameras

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Cellular Phones

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Handheld Instruments

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Board Mounted Power Supplies

SYNC/MODE

SYNC

LTC3411A

SW

PGOOD

PGND

SGND

2.2μH

2.5V

1.25A

2.5V TO 5.5V

887k

22pF

412k

680pF

3411a TA01a

22μF

12.1k

10μF

549k

Efficiency and Power Loss vs Output Current

OUTPUT CURRENT (mA)

0.1

1

10

0

40

30

100

1

0.1

0.01

0.001

0.0001

1000

100

10000

3411A TA01b

20

10

60

50

80

70

90

Burst Mode OPERATION

L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology

Corporation. All other trademarks are the property of their respective owners. Protected by

U.S. Patents including 5481178, 6580258, 6498466, 6611131.