LTC3453

1

3453fa

2.7

100

90

80

70

50

60

180

160

140

120

80

100

4.7

3453 TA01b

3.1

3.5

3.9

5.5

4.3

5.1

EFFICIENCY

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

The LTC

verter optimized for driving up to 4 white LEDs at a

combined current of up to 500mA from a single Li-Ion

battery input. The regulator operates in either synchro-

nous buck, synchronous boost, or buck-boost mode,

depending on input voltage and LED maximum forward

voltage. Optimum efficiency is achieved using a propri-

etary architecture that determines which LED requires the

largest forward voltage drop at its programmed current,

and regulates the common output rail for lowest dropout.

Efficiency of 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 current setting resistors and dual

enable pins. In shutdown, the supply current is only 6

µA.

A high constant operating frequency of 1MHz allows the

use of a small external inductor. The LTC3453 is offered

in a low profile (0.75mm) thermally enhanced 16-lead

(4mm x 4mm) QFN package.

■

Cell Phones

■

Portable Devices

Li-Ion Battery Range

µA

QFN Package

Synchronous Buck-Boost

High Power White LED Driver

High Efficiency Torch/Flash LED Driver

EN1 (TORCH)

GND

PGND

GND

D1: LUMILEDS LXCL-PWF1

L1: VISHAY DALE IDCS-2512

LED1

LED2

LED3

LED4

D1

3453 TA01a

EN1

0.1

µF

EN2

EN2 (FLASH)

8.25k

1%

3.48k

1%

EN1

EN2

0

1

0

1

0

0

1

1

0 (SHUTDOWN)

150mA

350mA

500mA

SW1

SW2

1-CELL

Li-Ion

2.7V to 4.2V

LTC3453

1MHz

BUCK-BOOST

2.2

µF

4.7

µF

L1

4.7

µH

150mA/500mA

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

All other trademarks are the property of their respective owners.