LTC3561

1

3561f

The LTC

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 0.11

Ω

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 240

µA. In shutdown, the

device draws <1

µA.

■

High Frequency Operation: Up to 4MHz

■

High Efficiency: Up to 95%

■

Current Mode Operation for Excellent Line

and Load Transient Response

■

Low Dropout Operation: 100% Duty Cycle

µA

■

Output Voltages from 0.8V to 5V

1A, 4MHz, Synchronous

Step-Down DC/DC Converter

Efficiency and Power Loss vs Load Current

Step-Down 2.5V/1A Regulator

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

LOAD CURRENT (mA)

10

50

75

70

65

60

55

100

95

90

85

80

1

10

1000

100

100

1000

3561 TA01

POWER LOSS

EFFICIENCY

, 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.

LTC3561

SW

PGND

SGND

2.2

µH

2.5V/1A

2.63V TO 5.5V

887k

412k

1000pF

3561 F01

22

µF

13k

22

µF

324k

NOTE: IN DROPOUT, THE OUTPUT TRACKS

THE INPUT VOLTAGE.