LTC3208

1

3208fa

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1x/1.5x/2x Charge Pump Provides Up to 95%

Efficiency

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Up to 1A Total Output Current

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17 Current Sources Available as MAIN, SUB, RGB,

CAM and AUX LED Drivers

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LED ON/OFF, Brightness Level and Display

Interface

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Low Noise Constant Frequency Operation with Flying

Capacitor Edge Rate Control

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Automatic Charge Pump Mode Switching

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Internal Soft-Start Limits Inrush Current During

Startup and Mode Switching

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Open/Shorted LED Protection

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Short-Circuit/Thermal Protection

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256 Brightness States for MAIN and SUB Displays

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4096 Color Combinations for the RGB Display

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5mm × 5mm 32-Lead QFN Plastic Package

High Current Software

Configurable Multidisplay

LED Controller

controller. The part contains a 1A high efficiency, low noise

charge pump to provide power to the MAIN, SUB, RGB, CAM

and AUX LED displays. The LTC3208 requires only small

ceramic capacitors and one current set resistor to form a

complete LED power supply and current controller.

The maximum display currents are set by a single ex-

ternal resistor. Current for each LED is controlled by a

precision internal current source. Dimming and On/Off

256 brightness levels are available for the MAIN and SUB

displays. 16 levels are available for the RGB and CAM

displays. Four AUX current sources can be independently

DAC controlled displays.

The LTC3208 charge pump optimizes efficiency based

on the voltage across the LED current sources. The part

powers up in 1x mode and will automatically switch to

boost mode whenever any enabled LED current source

begins to enter dropout. The first dropout switches the

part into 1.5x mode and a subsequent dropout switches

the LTC3208 into 2x mode. The part is available in a small

5mm

× 5mm 32-lead QFN package.

4-LED MAIN Display

Efficiency vs Input Voltage

C1P C1M C2P C2M

SCL/SDA

ENRGBS

CAMHL

CPO

MAIN1-4

SUB1-2

CAM1-4

RGB

AUX1-4

GND

LTC3208

4

2

4

3

4

MAIN

SUB

CAMERA

RGB

AUX

ENABLE DISABLE

LOW HI

24.3k

1%

3208 TA01a

C4

4.7

mF

C1

4.7

mF

C3

2.2

mF

C2

2.2

mF

3.0

60

80

100

3208 TA01b

40

20

50

70

90

30

10

0

3.6

3.8

3.2

4.0

3.4

4.4

4.2

4 LEDs AT 15mA/LED

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

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Video/Camera Phones with QVGA + Displays

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

trademarks are the property of their respective owners. Protected by U.S. Patents including

6411531.