LTC3206

1

3206f

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

■

Multidisplay Handheld Devices

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

Provides Up to 92% Efficiency

■

Up to 400mA Continuous Output Current

1-6 LED MAIN, 1-4 LED SUB and RGB LED Displays

■

Serial Interface

■

Low Noise Constant Frequency Operation*

■

16 Exponentially Spaced Dimming States Provides

128:1 Brightness Range for MAIN and SUB Displays

■

QFN Package

LED Controller

The LTC

troller. The part contains a high efficiency, low noise frac-

tional step-up/direct-connect charge pump to provide

power for both main and sub white LED displays plus an

RGB color LED display. The LTC3206 requires only four

small ceramic capacitors plus two resistors to form a

complete 3-display LED power supply and current

controller.

Maximum currents for the main/sub displays and RGB

display are set independently. Current for each LED is

controlled with an internal current source. Dimming and

ON/OFF control for all displays is achieved via a 2-wire

serial interface. Two auxiliary LED pins can be individually

assigned to either the MAIN or SUB displays. 16 individual

dimming states exist for both the MAIN and SUB displays.

Each of the RED, GREEN and BLUE LEDs have 16 dimming

states as well, resulting in up to 4096 color combinations.

The LTC3206 charge pump optimizes efficiency based on

up in direct-connect mode and automatically switches to

1.5x step-up mode once any enabled LED current source

begins to enter dropout. Internal circuitry prevents inrush

current and excess input noise during start-up and mode

switching. The LTC3206 is available in a 24-lead (4mm ×

4mm) QFN package.

* U.S. Patent 6,411,531

2.2µF

2.2µF

3206 TA01a

2.2µF

2.2µF

2.7V TO

4.5V

4

MAIN DISPLAY

SUB DISPLAY

RGB ILLUMINATOR

2

INTERFACE

2

3

RED

GREEN BLUE

LTC3206

SERIAL PORT

MAIN1-4

AUX 1

AUX 2

SUB1-2

RGB

CPO

5-LED Main Display Efficiency

vs Input Voltage

INPUT VOLTAGE (V)

3.0

60

80

100

3206 TA01b

40

20

50

70

90

30

10

0

3.6

3.9

3.3

4.2

FIVE LEDs AT 15mA/LED