1

LTC3452

3452f

5

× 20mA White LED Display + 200mA Camera Light Driver

Synchronous Buck-Boost

MAIN/CAMERA White LED Driver

Range

µA

(4mm

× 4mm) QFN Package

Torch and Flash Mode Efficiency

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

The LTC

verter optimized for driving two banks of white LEDs from

a single Li-Ion battery input. Five parallel LEDs can be

driven at up to 25mA each in the low power LED bank,

while two LEDs can be driven at up to 150mA each (or a

single LED at 300mA) in the high power LED bank. The

regulator operates in either synchronous buck, synchro-

nous boost or buck-boost mode, depending on input

voltage and LED maximum forward voltage. Optimum

efficiency is achieved by sensing which LED requires the

largest forward voltage drop at its programmed current,

and regulating the common output rail for lowest dropout.

Efficiency of 85% can be achieved over the entire usable

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

Maximum LED current for each LED display is program-

mable with a single external resistor. Dual enable pins

allow for PWM brightness control in the low power bank

and independent on/off control for the high current bank

(optimal for LED camera flash). In shutdown, the supply

current is only 6.5

µA.

A high constant operating frequency of 1MHz allows the

use of a small external inductor. The LTC3452 is offered

in a low profile (0.75mm) thermally enhanced 20-lead

(4mm

× 4mm) QFN package.

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

All other trademarks are the property of their respective owners.

1MHz

BUCK/BOOST

LTC3452

0.1

µF

10.2k

0mA TO

20mA

0mA TO

20mA

0mA TO

20mA

0mA TO

20mA

0mA TO

20mA

GND

GND

PGND

EXPOSED PAD

6.19k

2.2

µF

SINGLE

Li-Ion CELL

2.7V TO 4.2V

L

4.7

µH

MAIN DISPLAY LED BACKLIGHT

D1: AOT 2015

D2 TO D6: NICHIA NSCW100

L: COILCRAFT DO3314-472

200mA

SW1

SW2

D1

CAM

D2

D3

D4

D5

D6

4.7

µF

3452 TA01a

+

2.7

75

77

81

83

85

95

89

3.5

4.3

4.7

3452 TA01b

79

91

93

87

3.1

3.9

5.1

5.5

TORCH MODE AT 100mA

FLASH MODE AT 200mA

EFFICIENCY =

Σ