LTC3208 Datasheet, PDF (1/24 Pages) Linear Technology – High Current Software Confi gurable Multidisplay LED Controller

FEATURES
■ _{1x/1.5x/2x Charge Pump Provides Up to 95%}
Efficiency
■ _{Up to 1A Total Output Current}
■ _{17 Current Sources Available as MAIN, SUB, RGB,}
CAM and AUX LED Drivers
■ _{LED ON/OFF, Brightness Level and Display}
Configuration Programmable Using 2-Wire I²C™
Interface
■ _{Low Noise Constant Frequency Operation with Flying}
Capacitor Edge Rate Control
■ _{Automatic Charge Pump Mode Switching}
■ _{Internal Soft-Start Limits Inrush Current During}
Startup and Mode Switching
■ _{Open/Shorted LED Protection}
■ _{Short-Circuit/Thermal Protection}
■ _{256 Brightness States for MAIN and SUB Displays}
■ _{4096 Color Combinations for the RGB Display}
■ _{5mm × 5mm 32-Lead QFN Plastic Package}
U
APPLICATIO S
■ _{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.
LTC3208
High Current Software
Configurable Multidisplay
LED Controller
DESCRIPTIO
The LTC^®3208 is a highly integrated multidisplay LED
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
for all displays is achieved via the I²C serial interface.
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
assigned via the I²C port to the CAM, SUB, MAIN or AUX
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.
TYPICAL APPLICATIO
C2
C3
2.2mF 2.2mF
C1P C1M C2P C2M
MAIN
SUB
CAMERA
RGB
V_BAT
C1
4.7mF
V_BAT1,2,3
CPO
LTC3208
MAIN1-4
I²C
SCL/SDA SUB1-2
CAM1-4
ENABLE DISABLE
LOW HI
ENRGBS
CAMHL
R_REF
RGB
AUX1-4
GND
24.3k
1%
C4
4.7mF
4
2
4
3
4
AUX
3208 TA01a
4-LED MAIN Display
Efficiency vs Input Voltage
100
90
80
70
60
50
40
30
20 _{4 LEDs AT 15mA/LED}
10 ^{(TYP V}F ^{AT 15mA = 3.2V)}
T_A = 25°C
0
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
V_BAT (V)
3208 TA01b
3208fa
1