LTC3561 Просмотр технического описания (PDF) - Linear Technology

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LTC3561

1A, 4MHz, Synchronous Step-Down DC/DC Converter

Linear Technology 

FEATURES

■ Uses Tiny Capacitors and Inductor

■ High Frequency Operation: Up to 4MHz

■ High Switch Current: 1.4A

■ Low RDS(ON) Internal Switches: 0.110Ω

■ High Efficiency: Up to 95%

■ VIN: 2.63V to 5.5V

■ Stable with Ceramic Capacitors

■ Current Mode Operation for Excellent Line

and Load Transient Response

■ Short-Circuit Protected

■ Low Dropout Operation: 100% Duty Cycle

■ Low Shutdown Current: IQ ≤ 1µA

■ Low Quiescent Current: 240µA

■ Output Voltages from 0.8V to 5V

■ Low Noise Pulse-Skipping Operation

■ Small 8-Pin DFN Package

U

APPLICATIO S

■ Wireless LAN Power

■ Notebook Computers

■ Digital Cameras

■ Cellular Phones

■ Board Mounted Power Supplies

LTC3561

1A, 4MHz, Synchronous

Step-Down DC/DC Converter

DESCRIPTIO

The LTC®3561 is a constant-frequency, synchronous,

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

applications, it operates from a 2.63V 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 2mm or less in height. The output voltage is

adjustable from 0.8V to 5V. Internal synchronous 0.11Ω

power switches with 1.4A peak current ratings provide

high efficiency. The LTC3561’s current mode architecture

and external compensation allow the transient response

to be optimized over a wide range of loads and output

capacitors.

To further maximize battery life, the P-channel MOSFET is

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

no-load quiescent current is only 240µA. In shutdown, the

device draws <1µA.

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

All other trademarks are the property of their respective owners. Protected by U.S. Patents,

including 5481178, 6127815, 6304066, 6498466, 6580258, 6611131.

TYPICAL APPLICATIO

13k

1000pF

Step-Down 2.5V/1A Regulator

VIN

2.63V TO 5.5V

PVIN

SVIN

ITH

LTC3561

SW

SHDN/RT

SGND

324k

VFB

PGND

22µF

2.2µH

887k

412k

VOUT

2.5V/1A

22µF

NOTE: IN DROPOUT, THE OUTPUT TRACKS

THE INPUT VOLTAGE.

3561 F01

Efficiency and Power Loss vs Load Current

100

95

90

85

80

75

70

65

60

55

50

10

EFFICIENCY

1000

100

POWER LOSS

10

VIN = 3.3V

VOUT = 2.5V

fO = 1MHz 1

100

1000

LOAD CURRENT (mA)

3561 TA01

3561f

1

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