LTC3206
I
2
C Multidisplay
LED Controller
FEATURES
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DESCRIPTIO
Step-Up/Direct-Connect Fractional Charge Pump
Provides Up to 92% Efficiency
Up to 400mA Continuous Output Current
Independent Current and Dimming Control for
1-6 LED MAIN, 1-4 LED SUB and RGB LED Displays
LED Currents Programmable Using 2-Wire I
2
C™
Serial Interface
1% LED Current Matching
Low Noise Constant Frequency Operation*
Minimal Component Count
Automatic Soft-Start Limits Inrush Current
16 Exponentially Spaced Dimming States Provides
128:1 Brightness Range for MAIN and SUB Displays
Up to 4096 Color Combinations for RGB Display
Low Operating Current: I
VIN
= 180µA
Tiny, Low Profile 24-Lead (4mm
×
4mm
×
0.75mm)
QFN Package
The LTC
®
3206 is a highly integrated multidisplay LED con-
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
V
IN
and LED forward voltage conditions. The part powers
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.
APPLICATIO S
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Cellular Phones
Wireless PDAs
Multidisplay Handheld Devices
, LTC and LT are registered trademarks of Linear Technology Corporation.
I
2
C is a trademark of Philips Electronics N.V.
* U.S. Patent 6,411,531
TYPICAL APPLICATIO
2.2µF
2.2µF
V
IN
2.7V TO
4.5V
V
IN
2.2µF
LTC3206
MAIN1-4
AUX 1
SUB1-2
AUX 2
I
2
C SERIAL
INTERFACE
2
SERIAL PORT RGB
I
RGB
I
MS
3
2
4
CPO
MAIN DISPLAY
SUB DISPLAY
RGB ILLUMINATOR
EFFICIENCY (P
LED
/P
IN
) (%)
2.2µF
RED
GREEN BLUE
3206 TA01a
U
5-LED Main Display Efficiency
vs Input Voltage
100
90
80
70
60
50
40
30
20
10
FIVE LEDs AT 15mA/LED
(TYP V
F
AT 15mA = 3.2V)
T
A
= 25°C
3.3
3.6
3.9
INPUT VOLTAGE (V)
4.2
3206 TA01b
U
U
0
3.0
3206f
1
LINER [ LINEAR TECHNOLOGY ]
