LT3465/LT3465A

1

3465af

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

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

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Inherently Matched LED Current

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Drives Up to Six LEDs from a 3.6V Supply

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No External Schottky Diode Required

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1.2MHz Switching Frequency (LT3465)

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2.4MHz Switching Frequency Above AM Broadcast

Band (LT3465A)

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Automatic Soft-Start (LT3465)

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Open LED Protection

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High Efficiency: 81% (LT3465) 79% (LT3465A)

Typical

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Requires Only 0.22

µF Output Capacitor

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Low Profile (1mm) SOT-23 Packaging

1.2MHz/2.4MHz White LED

Step-Up Converters with

Built-In Schottky in ThinSOT

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Cellular Phones

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PDAs, Handheld Computers

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Digital Cameras

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MP3 Players

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GPS Receivers

The LT

designed to drive up to six LEDs in series from a Li-Ion cell.

Series connection of the LEDs provides identical LED

currents and eliminates the need for ballast resistors.

These devices integrate the Schottky diode required exter-

nally on competing devices. Additional features include

output voltage limiting when LEDs are disconnected, one-

pin shutdown and dimming control. The LT3465 has

internal soft-start.

The LT3465 switches at 1.2MHz, allowing the use of tiny

external components. The faster LT3465A switches at

2.4MHz. Constant frequency switching results in low input

noise and a small output capacitor. Just 0.22

µF is required

for 3-, 4- or 5-LED applications.

The LT3465 and LT3465A are available in low profile

(1mm) 6-lead SOT-23 (ThinSOT

ThinSOT is a trademark of Linear Technology Corporation.

Figure 1. Li-Ion Powered Driver for Four White LEDs

SW

LT3465/

LT3465A

CTRL

3465A F01a

10

Ω

C1

1

µF

C2

0.22

µF

C1, C2: X5R OR X7R DIELECTRIC

L1: MURATA LQH32CN220

L1

22

µH

3V TO 5V

SHUTDOWN

AND DIMMING

CONTROL

FB

GND

LED CURRENT (mA)

0

78

80

20

3465A F01b

76

60

70

68

66

64

62

72

74

5

10

15

82

4 LEDs

LT3465

LT3465A

Conversion Efficiency