LT3505

1

3505fc

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

1.2A, Step-Down

Switching Regulator in

3mm

× 3mm DFN

converter with an internal 1.4A power switch. The wide

operating input range of 3.6V to 36V (40V maximum)

makes the LT3505 ideal for regulating power from a wide

variety of sources, including unregulated wall transform-

ers, 24V industrial supplies and automotive batteries. The

oscillatorcanbeprogrammedforhighfrequencyoperation

allowing the use of tiny, low cost external components or

it can be programmed for lower frequency operation to

maximize efficiency.

Cycle-by-cycle current limit provides protection against

shorted outputs and soft-start eliminates input current

surge during start-up. The low current (<2µA) shutdown

mode provides output disconnect, enabling easy power

management in battery-powered systems.

750kHz, 3.3V Step-Down Converter

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

All other trademarks are the property of their respective owners.

!

Wide Input Range: 3.6V to 36V Operating,

40V Maximum

!

Up to 1.2A Output Current

!

Resistor-Programmable Fixed-Frequency Operation

from 200kHz to 3MHz

!

Output Adjustable Down to 780mV

!

Short-Circuit Robust

!

Uses Tiny Capacitors and Inductors

!

Soft-Start

!

Low Shutdown Current: <2µA

!

!

Thermally Enhanced, Low Profile 3mm x 3mm

DFN-8 and MSOP-8 Packages

!

Automotive Battery Regulation

!

Industrial Control Supplies

!

Wall Transformer Regulation

!

Distributed Supply Regulation

!

Battery-Powered Equipment

4.2V TO 36V

ON OFF

0.1

µF 10µH

36.5k

10

µF

3505 TA01

22pF

68pF

1

µF

75.0k

11.3k

3.3V

69.8k

GND

BOOST

FB

SW

LT3505

SHDN

Efficiency

LOAD CURRENT (A)

70

80

60

50

0.4

0.8

1.2

0.2

0

0.6

1.0

90

65

75

55

85

L = 10 H