1

LTC1772

1772fb

Constant Frequency

Current Mode Step-Down

DC/DC Controller in SOT-23

The LTC

down DC/DC controller providing excellent AC and DC load

and line regulation. The device incorporates an accurate

undervoltage lockout feature that shuts down the LTC1772

when the input voltage falls below 2.0V.

The LTC1772 provides a

±2.5% output voltage accuracy

and consumes only 270

µA of quiescent current. For

applications where efficiency is a prime consideration, the

LTC1772 is configured for Burst Mode operation, which

enhances efficiency at low output current.

To further maximize the life of a battery source, the

external P-channel MOSFET is turned on continuously in

dropout (100%dutycycle).In shutdown, the device draws

a mere 8

µA. High constant operating frequency of 550kHz

allows the use of a small external inductor.

The LTC1772 is available in a small footprint 6-lead

SOT-23.

■

Cellular Telephones

■

Distributed 3.3V, 2.5V or 1.8V Power Systems

■

High Efficiency: Up to 94%

■

Constant Frequency 550kHz Operation

■

Tiny 6-Lead SOT-23 Package

Transient Response

µA

µA Supply Current

■

±2.5% Reference Accuracy

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

Burst Mode is a registered trademark of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

Figure 1. High Efficiency, High Output Current 2.5V/2A Regulator

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

LTC1772

10k

R1

0.03

Ω

174k

80.6k

L1

4.7

µH

M1

D1

220pF

C1: TAIYO YUDEN LMK325BJ106K-T

C2A: SANYO 6TPA47M

C2B: AVX 0805ZC105KAT1A

D1: MOTOROLA MBRM120T3

L1: MURATA LQN6C-4R7

M1: FAIRCHILD FDC638P

R1: IRC LRC-LR1206-01-R030F

GND

6

5

4

1772 F01a

1

2

3

PGATE

C1

10

µF

10V

C2B

1

µF

10V

2.5V

TO 9.8V

2.5V

2A

C2A

47

µF

6V

+

LOAD CURRENT (mA)

100

90

80

70

60

50

40

100

1000

10000

10

1

1772 F01b

Efficiency vs Load Current