LTC3218

1

3218fa

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

400mA Single Wire

Camera LED Charge Pump

DC/DC converter capable of driving high current LEDs at up

to 400mA from a 2.9V to 4.5V input. A low external parts

count (one flying capacitor, two programming resistors and

ideally suited for small, battery-powered applications.

Built-in soft-start circuitry prevents excessive inrush cur-

rent during start-up. High switching frequency enables the

use of small external capacitors. A built-in 2-second timer

protects the LED during flash mode.

Output current level is programmed by an external re-

sistor. LED current is regulated using an internal high

side 220mΩ sense resistor. Automatic mode switching

optimizes efficiency by monitoring the voltage across the

charge pump and switching modes only when dropout

is detected. The part is available in a low profile 3mm ×

2mm 10-lead DFN package.

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

All other trademarks are the property of their respective owners. Protected by U.S. Patents,

including 6411531.

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Low Noise Constant-Frequency Operation

■

Multi-Mode Operation: 1x or 2x Boost Mode

■

Automatic Mode Switching

■

High Output Current: 150mA (Continuous), 400mA

(Pulsed) From Li-Ion/Polymer Input

■

2-Second Flash Current Timeout for LED Protection

■

Automatic Soft-Start

■

Output Disconnect

■

No Inductors

■

220mΩ Internal High Side Current Sense Resistor

■

Single Resistor Programming Capability

■

Tiny Application Circuit (3mm × 2mm DFN Package,

All Components < 1mm High)

■

LED Torch/Flash Supply for DSCs/Cellphones

2.2

µF

2.2

µF

4.7

µF

LED

AOT2015

2.9V TO 4.5V

ENT

LTC3218

CP

CM

3218 TA01

CPO

GND

10.2k

1%

ENF

0

0

1

1

0 (SHUTDOWN)

100mA (TORCH)

290mA

390mA (FLASH)

ENT

0

1

0

1

ENF

ENABLED

DISABLED

ENABLED

DISABLED

2.9

4.5

3.3

3.7

4.1

3.1

3.5

3.9

4.3

3218 TA01b

40

50

70

80

90

100

60

50mA

150mA

300mA