LTC3544BEUD-TRPBF 데이터 시트보기 (PDF) - Linear Technology

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LTC3544BEUD-TRPBF

Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA

Linear Technology 

LTC3544B

Quad Synchronous

Step-Down Regulator: 2.25MHz,

300mA, 200mA, 200mA, 100mA

Features

■ High Efficiency: Up to 95%

■ Four Independent Regulators Provide Up to 300mA,

200mA, 200mA and 100mA Output Current

■ 2.25V to 5.5V Input Voltage Range

■ 2.25MHz Constant Frequency Operation

■ No Schottky Diodes Required

■ Low Dropout Operation: 100% Duty Cycle

■ Pulse Skipping at Low Load for Minimum Ripple

■ 0.8V Reference Allows Low Output Voltages

■ Shutdown Mode Draws <1µA Supply Current

■ Current Mode Operation for Excellent Line and Load

Transient Response

■ Overtemperature Protected

■ Low Profile (3mm × 3mm) 16-Lead QFN Package

Applications

■ Cellular Telephones

■ Personal Information Appliances

■ Wireless and DSL Modems

■ Digital Still Cameras

■ Media Players

■ Portable Instruments

Description

The LTC®3544B is a quad, high efficiency, monolithic

synchronous buck regulator using a constant frequency,

current mode architecture. The four regulators operate in-

dependently with separate run pins. The 2.25V to 5.5V input

voltage range makes the LTC3544B well suited for single

Li-Ion/polymer battery-powered applications. 100% duty

cycle provides low dropout operation, extending battery

runtime in portable systems. At moderate and low output

load levels PWM pulse skip mode operation provides very

low output ripple voltage for noise sensitive applications.

Switching frequency is internally set to 2.25MHz, al-

lowing the use of small surface mount inductors and

capacitors.

The internal synchronous switches increase efficiency

and eliminate the need for external Schottky diodes. Low

output voltages are easily supported with the 0.8V feedback

reference voltage.

The LTC3544B is available in a low profile (0.75mm)

(3mm × 3mm) QFN package.

L, LT, LTC, LTM, Linear Technology and the Linear logo 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, 5994885.

Typical Application

High Efficiency Quad Step-Down Converter

VIN

2.25V TO 5.5V

VOUT2

1.5V

4.7µF

CER

4.7µF

CER

4.7µH

93.1k

107k

VCC

RUN200B

SW200B

VFB200B

PVIN

RUN200A

SW200A

VFB200A

LTC3544B

VOUT4

1.8V

4.7µF

CER

3.3µH

133k

107k

RUN300

SW300

VFB300

GNDA

RUN100

SW100

VFB100

PGND

3.3µH

100k

VOUT3

0.8V

4.7µF

CER

10µH

59k

118k

VOUT1

1.2V

4.7µF

CER

3544B TA01a

Efficiency vs Load Current, 300mA

Channel, All Other Channels Off

100

1

VOUT = 1.5V

90 TA = 25°C

80

70

EFFICIENCY

0.1

60

50

POWER LOSS

40

30

0.01

20

10

0

0.0001

0.001

0.01

VIN = 2.5V

VIN = 3.6V

VIN = 4.3V 0.001

0.1

1

LOAD CURRENT (A)

3544B TA01b

3544bfb



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