LTC3409IDD データシートの表示（PDF） - Linear Technology

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LTC3409IDD

600mA Low VIN Buck Regulator in 3mm × 3mm DFN

Linear Technology 

LTC3409

600mA Low VIN Buck

Regulator in 3mm × 3mm DFN

FEATURES

■ 1.6V to 5.5V Input Voltage Range

■ Internal Soft-Start

■ Selectable 1.7MHz or 2.6MHz Constant Frequency

Operation

■ Internal Oscillator can be Synchronizable to an

External Clock, 1MHz to 3MHz Range

■ High Efficiency: Up to 95%

■ Very Low Quiescent Current: Only 65μA During

Burst Mode® Operation

■ 600mA Output Current (VIN = 1.8V, VOUT = 1.2V)

■ 750mA Peak Inductor Current

■ No Schottky Diode Required

■ Low Dropout Operation: 100% Duty Cycle

■ 0.613V Reference Voltage

■ Stable with Ceramic Capacitors

■ Shutdown Mode Draws <1μA Supply Current

■ Current Mode Operation for Excellent Line and Load

Transient Response

■ Overtemperature Protection

■ Available in a Low Profile (0.75mm) 8-Lead

(3mm × 3mm) DFN Package

APPLICATIONS

■ Cellular Phones

■ Digital Cameras

■ MP3 Players

DESCRIPTION

The LTC®3409 is a high efficiency, monolithic synchronous

buck regulator using a constant frequency, current mode

architecture. The output voltage is adjusted via an external

resistor divider.

Fixed switching frequencies of 1.7MHz and 2.6MHz are

supported. Alternatively, an internal PLL will synchronize

to an external clock in the frequency range of 1MHz to

3MHz. This range of switching frequencies allows the

use of small surface mount inductors and capacitors,

including ceramics.

Supply current during Burst Mode operation is only

65μA dropping to <1μA in shutdown. The 1.6V to 5.5V

input voltage range makes the LTC3409 ideally suited

for single cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd

or NiMH battery-powered applications. 100% duty cycle

capability provides low dropout operation, extending bat-

tery life in portable systems. Burst Mode operation can be

user-enabled, increasing efficiency at light loads, further

extending battery life.

The internal synchronous switch increases efficiency and

eliminates the need for an external Schottky diode. Internal

soft-start offers controlled output voltage rise time at start-

up without the need for external components.

, 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, 6304066, 6127815,

6498466, 6611131.

TYPICAL APPLICATION

High Efficiency Step-Down Converter

VIN

1.8V TO 5.5V

4.7μF

CER

LTC3409

VIN

SW

RUN

MODE VFB

SYNC GND

2.2μH*

10pF

133k 255k

*SUMIDA CDRH2D18/LD

3409 TA01

VOUT

1.8V

10μF

CER

Burst Mode Efficiency, 1.8VOUT

100

1.0

90 2.5VIN, BURST

80

70

4.2VIN, BURST

0.1

60

3.6VIN, BURST

50

0.01

40

30

POWER LOST

3.6VIN, BURST

0.001

20

10

0

0.0001

0.1

1

10

100

1000

LOAD CURRENT (mA)

3409 TA01b

3409fc

1

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