LTC3121

1

3121fa

For more information www.linear.com/LTC3121

Typical applicaTion

FeaTures

DescripTion

15V, 1.5A Synchronous

Step-Up DC/DC Converter

with Output Disconnect

The LTC®3121 is a synchronous step-up DC/DC converter

withtrueoutputdisconnectandinrushcurrentlimiting.The

1.5A current limit along with the ability to program output

voltages up to 15V makes the LTC3121 well suited for a

varietyofdemandingapplications.Oncestarted,operation

will continue with inputs down to 500mV, extending run

time in many applications.

The LTC3121 features output disconnect in shutdown,

dramatically reducing input power drain and enabling

from 100kHz to 3MHz optimizes applications for highest

efficiency or smallest solution footprint. The oscillator

can also be synchronized to an external clock for noise

sensitive applications. Selectable Burst Mode operation

reducesquiescentcurrentto25µA,ensuringhighefficiency

across the entire load range. An internal soft-start limits

inrush current during start-up.

Otherfeaturesincludea<1µAshutdowncurrentandrobust

protectionundershort-circuit,thermaloverload,andoutput

overvoltage conditions. The LTC3121 is offered in a low

profile 12-lead (3mm × 4mm × 0.75mm) DFN package.

5V to 12V Synchronous Boost Converter with Output Disconnect

applicaTions

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Output Voltage Range: 2.2V to 15V

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Output Disconnects from Input When Shut Down

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Synchronous Rectification: Up to 95% Efficiency

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Inrush Current Limit

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Up to 3MHz Adjustable Switching Frequency

Synchronizable to External Clock

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Output Overvoltage Protection

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Soft-Start

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12-Lead, 3mm × 4mm Thermally Enhanced DFN

Package

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PCI Express Cards/Systems

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Piezo Actuators

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Small DC Motors

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12V Analog Rail From Battery, 5V, or Backup Capacitor

L

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

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

property of their respective owners.

Efficiency Curve

3121 TA01a

SD

PWM/SYNC

RT

CAP

FB

LTC3121

SGND

PGND

210k

390pF

SW

6.8µH

113k

1.02M

10pF

4.7µF

100nF

22µF

12V

400mA

57.6k

5V

4.7µF

ON

OFF

PWM

BURST

LOAD CURRENT (mA)

0.01

100

90

70

50

40

80

60

30

20

10

0

10

1

0.1

0.01

10

0.1

3121 TA01b

600

1

100

PWM

Burst Mode

OPERATION

PWM POWER LOSS