1

LT3477

3477fb

3A, DC/DC Converter

with Dual Rail-to-Rail

Current Sense

(Boost, Inverting, SEPIC, Flyback)

(4mm

× 4mm) QFN and 20-Lead TSSOP Packages

■

High Power LED Driver

■

Input/Output Current Limited Boost, SEPIC,

Inverting, Flyback Converters

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

Efficiency

330mA LED Driver with Open LED Protection

The LT

verter with dual rail-to-rail current sense amplifiers and an

internal 3A, 42V switch. It combines a traditional voltage

feedback loop and two unique current feedback loops to

operate as a constant-current, constant-voltage source.

Both current sense voltages are set at 100mV and can be

Efficiency of up to 91% can be achieved in typical applica-

tions. The LT3477 features a programmable soft-start func-

tion to limit inductor current during start-up. Both inputs

of the error amplifier are available externally allowing posi-

tive and negative output voltages (Boost, Inverting, SEPIC,

Flyback). The switching frequency is programmable from

200kHz to 3.5MHz through an external resistor.

Available in thermally enhanced 20-pin (4mm

× 4mm)

QFN and 20-pin TSSOP packages, the LT3477 provides a

complete solution for both constant-voltage and con-

stant-current applications.

FBN

200k

3.3

µF

3.3

µF

5V

33nF

4.7nF

330mA

3477 TA01a

10k

22k

1k

0.3

Ω

SW

10

µH

FBP

SS

GND

LT3477

SHDN

SHDN

0

70

75

80

0.4

3477 TA01b

65

60

50

0.1

0.2

0.3

55

90

85

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