LTC3454 Просмотр технического описания (PDF) - Linear Technology

Номер в каталоге

Компоненты Описание

производитель

LTC3454

1A Synchronous Buck-Boost High Current LED Driver

Linear Technology 

LTC3454

1A Synchronous Buck-Boost

High Current LED Driver

FEATURES

n High Efficiency: >90% Typical in Torch Mode,

>80% in Flash Mode

n Wide VIN Range: 2.7V to 5.5V

n Up to 1A Continuous Output Current

n 3.5% LED Current Programming Accuracy

n Internal Soft-Start

n Open/Shorted LED Protection

n Constant Frequency 1MHz Operation

n Zero Shutdown Current

n Overtemperature Protection

n Small Thermally Enhanced 10-Lead (3mm × 3mm)

DFN Package

APPLICATIONS

n Cell Phone Camera Flash

n Cell Phone Torch Lighting

n Digital Cameras

n PDAs

n Misc Li-Ion LED Drivers

DESCRIPTION

The LTC®3454 is a synchronous buck-boost DC/DC

converter optimized for driving a single high power LED

at currents up to 1A from a single cell Li-Ion battery in-

put. The regulator operates in either synchronous buck,

synchronous boost, or buck-boost mode depending on

input voltage and LED forward voltage. PLED/PIN efficiency

greater than 90% can be achieved over the entire usable

range of a Li-Ion battery (2.7V to 4.2V).

LED current is programmable to one of four levels, includ-

ing shutdown, with dual external resistors and dual enable

inputs. In shutdown no supply current is drawn.

A high constant operating frequency of 1MHz allows the

use of small external components. The LTC3454 is offered

in a low profile (0.75mm) thermally enhanced 10-lead

(3mm × 3mm) DFN package.

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

All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

High Efficiency Torch/Flash LED Driver

VIN

2.7V TO 4.2V

1-CELL Li-Ion

10μF

L1

5μH

VIN SW1

SW2 VOUT

10μF

ILED

A

D

LED

B

C

LED

EN2 EN1 ILED

0 0 0 (SHUTDOWN)

0

EN1 (TORCH) 1

1 150mA

0 850mA

1 1 1A

VC

1MHz

BUCK-BOOST

EN2 (FLASH)

ISET1

0.1μF

LED: LUMILEDS LXL-PWF1

L1: SUMIDA CDRH6D28-5RONC

ISET2

LTC3454

GND (EXPOSED PAD)

RISET2

3.65k

1%

3454 TA01a

RISET1

20.5k

1%

LED Power Efficiency vs VIN

100

95

ILED = 150mA

90

85

ILED = 1A

80

75

70

65 TA = 25°C

EFFICIENCY = (VOUT – VLED)ILED/VINIIN

60

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

VIN (V)

3454 TA01b

3454fa

1

Share Link: