LTC3210 Datasheet, PDF (1/16 Pages) Linear Technology – MAIN/CAM LED Controller in 3mm × 3mm QFN

FEATURES
■ _{Low Noise Charge Pump Provides High Efficiency}
with Automatic Mode Switching
■ _{Multimode Operation: 1x, 1.5x, 2x}
■ _{Individual Full-Scale Current Set Resistors}
■ _{Up to 500mA Total Output Current}
■ _{Single Wire EN/Brightness Control for MAIN and}
CAM LEDs (8 Brightness Steps)
■ _{64:1 Brightness Control Range for MAIN Display}
■ _{Four 25mA Low Dropout MAIN LED Outputs}
■ _{One 400mA Low Dropout CAM LED Output}
■ _{Low Noise Constant Frequency Operation*}
■ _{Low Shutdown Current: 3µA}
■ _{Internal Soft-Start Limits Inrush Current During}
Startup and Mode Switching
■ _{Open/Short LED Protection}
■ _{No Inductors}
■ _{3mm × 3mm 16-Lead Plastic QFN Package}
U
APPLICATIO S
■ _{Multi-LED Light Supply for Cellphones/DSCs/PDAs}
, 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.
LTC3210
MAIN/CAM LED Controller
in 3mm × 3mm QFN
DESCRIPTIO
The LTC^®3210 is a low noise charge pump DC/DC converter
designed to drive four MAIN LEDs and one high current
CAM LED for camera lighting. The LTC3210 requires only
four small ceramic capacitors and two current set resis-
tors to form a complete LED power supply and current
controller.
Built-in soft-start circuitry prevents excessive inrush cur-
rent during start-up and mode changes. High switching
frequency enables the use of small external capacitors.
Independent MAIN and CAM full-scale current settings
are programmed by two external resistors. Shutdown
mode and current output levels are selected via two logic
inputs.
The full-scale current through the LEDs is programmed
via external resistors. ENM and ENC are toggled to adjust
the LED currents via internal counters and DACs. The
part is shut down when both ENM and ENC are low for
150µs (typ).
The charge pump optimizes efficiency based on the volt-
age 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 en-
ter dropout. The LTC3210 is available in a 3mm × 3mm
16-lead QFN package.
TYPICAL APPLICATIO
C2
2.2µF
C3
2.2µF
V_BAT
C1
2.2µF
ENM
ENC
C1P C1M C2P C2M
V_BAT
CPO
LTC3210
ENM
ENC
RM
MLED1
MLED2
MLED3
MLED4
CLED
RC
GND
30.1k
1%
24.3k
1%
C4
2.2µF
4-LED MAIN Display
Efficiency vs V_BAT Voltage
100
90
MAIN
80
CAM
70
60
50
40
30
3210 TA01
20 _{4 LEDs AT 9mA/LED}
10 ^{(TYP V}F ^{AT 9mA = 3V, NICHIA NSCW100)}
T_A = 25°C
0
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
V_BAT (V)
3210 TA01b
3210f
1