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LTC1771

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Very Low Standby Current: 10

µA

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Available in Space-Saving 8-Lead MSOP Package

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Output Currents: Up to 5A

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High Efficiency: Over 93% Possible

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±2% Output Accuracy

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Very Low Dropout Operation: 100% Duty Cycle

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Current Mode Operation for Excellent Line and

Load Transient Response

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Defeatable Burst Mode

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Short-Circuit Protected

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Optional Programmable Soft-Start

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The LTC

down DC/DC controller that draws as little as 10

µA DC

supply current to regulate the output at no load while

maintaining high efficiency for loads up to several amps.

The LTC1771 drives an external P-channel power MOSFET

using a current mode, constant off-time architecture. An

external sense resistor is used to program the operating

current level. Current mode control provides short-circuit

protection, excellent transient response and controlled

start-up behavior. Burst Mode operation enables the

LTC1771 to maintain high efficiency down to extremely

low currents. Shutdown mode further reduces the supply

current to a mere 2

µA. For low noise applications, Burst

Mode operation can be easily disabled with the MODE pin.

Wide input supply range of 2.8V to 18V (20V maximum)

and 100% duty cycle operation for low dropout make the

LTC1771 ideal for a wide variety of battery-powered appli-

cations where maximizing battery life is important.

The LTC1771’s availability in both 8-lead MSOP and SO

packages provides for a minimum area solution.

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Cellular Telephones and Wireless Modems

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1- to 4-Cell Lithium-Ion-Powered Applications

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Portable Instruments

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Battery-Powered Equipment

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Battery Chargers

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Scanners

Figure 1. High Efficiency Step-Down Converter

10

µA Quiescent Current

High Efficiency Step-Down

DC/DC Controller

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

Burst Mode is a trademark of Linear Technology Corporation.

RUN/SS

4.5V TO 18V

10k

0.05

Ω

R2

1.64M

1%

R1

1M

1%

M1

Si6447DQ

UPS5817

L1

15

µH

22OpF

5pF

22

µF

25V

150

µF

6.3V

3.3V

2A

1771 F01

0.01

µF

PGATE

MODE

LTC1771

GND

SENSE

+

+

LTC1771 Efficiency

LOAD CURRENT (mA)

100

90

80

70

60

50

40

0.1

1

100

1000

10000

1771 F01b

10

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO