1

LTC3406B

3406bfa

■

High Efficiency: Up to 96%

■

■

2.5V to 5.5V Input Voltage Range

■

1.5MHz Constant Frequency Operation

■

No Schottky Diode Required

■

Low Dropout Operation: 100% Duty Cycle

■

Low Quiescent Current: 300µA

■

0.6V 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 (1mm) ThinSOT

The LTC

nous buck regulator using a constant frequency, current

mode architecture. The device is available in an adjustable

version and fixed output voltages of 1.5V and 1.8V. Supply

current with no load is 300µA and drops to <1µA in

shutdown. The 2.5V to 5.5V input voltage range makes the

LTC3406B ideally suited for single Li-Ion battery-powered

applications. 100% duty cycle provides low dropout op-

eration, extending battery life in portable systems. PWM

pulse skipping mode operation provides very low output

ripple voltage for noise sensitive applications.

Switching frequency is internally set at 1.5MHz, allowing

the use of small surface mount inductors and capacitors.

The internal synchronous switch increases efficiency and

eliminates the need for an external Schottky diode. Low

output voltages are easily supported with the 0.6V feed-

back reference voltage. The LTC3406B is available in a low

profile (1mm) ThinSOT package. Refer to LTC3406 for

applications that require Burst Mode

■

Personal Information Appliances

■

Wireless and DSL Modems

■

Digital Still Cameras

■

MP3 Players

■

Portable Instruments

Figure 1a. High Efficiency Step-Down Converter

1.5MHz, 600mA

Synchronous Step-Down

Regulator in ThinSOT

Figure 1b. Efficiency vs Load Current

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

Burst Mode is a registered trademark of Linear Technology Corporation.

ThinSOT is a trademark of Linear Technology Corporation.

Protected by U.S. Patents, including 6580258, 5481178.

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

4.7µF

CER

2.7V

TO 5.5V

*

**

†

LTC3406B-1.8

RUN

3

2.2µH*

3406B F01a

MURATA LQH32CN2R2M33

TAIYO YUDEN JMK212BJ475MG

TAIYO YUDEN JMK316BJ106ML

5

4

1

2

SW

GND

10µF

CER

1.8V

600mA

OUTPUT CURRENT (mA)

0.1

10

1000

100

90

80

70

60

50

40

30

20

10

3406B F01b

1

100

VIN = 2.7V

VOUT = 1.8V

VIN = 3.6V

VIN = 4.2V