LTC3672B-1

1

3672B1f

0

400

350

300

250

200

150

100

50

3672b1 TA01b

100

95

90

85

80

75

70

65

60

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Monolithic Fixed-Output

400mA Buck Regulator with Dual

150mA LDOs in 2mm

× 2mm DFN

400mA synchronous buck regulator and two 150mA low-

dropout linear regulators (LDOs), where one of the LDOs

can be powered from the buck output to improve efficiency.

Constant-frequency 2.25MHz operation is maintained

down to very light loads. The input supply range of 2.9V

to 5.5V is especially well-suited for single-cell Lithium-Ion

and Lithium-Polymer applications, and for powering low

voltage ASICs from 3.3V or 5V rails.

The LTC3672B-1 regulates 1.8V at the buck output, 1.2V

at the LDO1 output, and 2.8V at the LDO2 output. Exter-

nal component count is minimal—all that is needed is a

single inductor, an input capacitor, and output capacitors

for each of the three outputs. Control loop compensation

is internal to the LTC3672B-1.

The LTC3672B-1 is available in a 2mm

× 2mm × 0.75mm

8-Lead DFN package.

Buck DC/DC Efficiency vs Load

■

Triple Output Supply From a Single 2.9V to 5.5V Input

■

Buck DC/DC: Fixed 1.8V Output, Up to 400mA

■

LDO1: Fixed 1.2V Output, Up to 150mA

■

LDO2: Fixed 2.8V Output, Up to 150mA

■

±2.5% Reference Accuracy

■

Constant Frequency 2.25MHz Operation

■

Minimum External Component Count

■

Current Mode Operation for Excellent Line and Load

Transient Response

■

Internal Soft-Start for Each Output

■

Single Enable Pin Turns On/Shuts Down All Three

Outputs

■

Tiny 2mm

× 2mm × 0.75mm DFN Package

■

DMB Cellphones

■

Handheld Products (PDA, PMP, GPS)

■

Multivoltage Power for Digital Logic, I/O, FPGAs,

CPLDs, ASICs, CPUs, and RF Chipsets

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

trademarks are the property of their respective owners.

LTC3672B-1

GND

ENALL

SW

1.8V

400mA

(250mA IF LDO1

FULLY-LOADED)

1.2V

150mA

2.2 F

4.7 H

ENABLE

INPUT

2.8V

UP TO 150mA

(SUBJECT TO DROPOUT

LIMITATIONS)

BUCKOUT

LDO1

LDO2

3672b1 TA01

1 F

1 F

10 F

2.9V TO 5.5V