LTC3407A-2

1

3407a2f

■

and Load Transient Response

■

Short-Circuit Protected

■

Output Voltages from 5V down to 0.6V

■

Optional External Soft-Start

× 3mm

DFN Packages

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

■

Cellular Phones

Dual Synchronous 800mA,

2.25MHz Step-Down

DC/DC Regulator

The LTC

nous step-down DC/DC converter. Intended for low power

applications, it operates from a 2.5V to 5.5V input voltage

range and has a constant 2.25MHz switching frequency,

enabling the use of tiny, low cost capacitors and inductors

1mm or less in height. Each output voltage is adjustable

from 0.6V to 5V. Internal synchronous 0.35

Ω, 1A power

switches provide high efficiency without the need for

external Schottky diodes.

A user selectable mode input is provided to allow the user

to trade-off ripple noise for low power efficiency. Burst

Mode

loads, while Pulse Skip Mode provides the lowest ripple

noise at light loads.

To further maximize battery life, the P-channel MOSFETs

are turned on continuously in dropout (100% duty cycle),

and both channels draw a total quiescent current of only

40

μA. In shutdown, the device draws <1μA.

Efficiency/Power Loss Curve

1mm High 2.5V/1.8V at 800mA Step-Down Regulators

RUN/SS2

TO 5.5V

AT 800mA

AT 800mA

RUN/SS1

POR

SW1

GND

SW2

MODE/SYNC

LTC3407A-2

10

μF

100k

RESET

22pF

22pF

2.2

μH

2.2

μH

887k

887k

442k

280k

10

μF

10

μF

3407A2 TA01

, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology

Corporation. All other trademarks are the property of their respective owners. Protected by

U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131.

LOAD CURRENT (mA)

1

0

30

20

10

70

60

50

40

100

0.0001

0.001

0.1

0.01

1

90

80

10

100

1000

3407A2 TA02

2.5V

Burst Mode OPERATION

NO LOAD ON OTHER CHANNEL

1.8V