LTC3210-2 Datasheet, PDF (1/16 Pages) Linear Technology – MAIN/CAM LED Controllers with 32-Step Brightness Control in 3mm × 3mm QFN

LTC3210-2/LTC3210-3
MAIN/CAM LED Controllers
with 32-Step Brightness Control
in 3mm × 3mm QFN
FEATURES
DESCRIPTION
■ _{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
■ _{32:1 Linear Brightness Control Range for}
MAIN Display
■ _{Three or 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}
APPLICATIONS
■ _{Multi-LED Light Supply for Cellphones/DSCs/PDAs}
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by US Patents including 6411531.
The LTC^®3210-2/LTC3210-3 are low noise charge pump
DC/DC converters designed to drive three or four MAIN
LEDs and one high current CAM LED for camera lighting.
The LTC3210-2/LTC3210-3 require only four small ceramic
capacitors and two current set resistors 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. ENM and ENC are toggled to adjust
the LED currents via internal counters and DACs. A 5-bit
linear DAC (32 steps) provides high resolution brightness
control for the MAIN display.
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 enter
dropout. The LTC3210-2/LTC3210-3 are available in a
3mm × 3mm 16-lead QFN package.
TYPICAL APPLICATION
C2
2.2μF
C3
2.2μF
V_BAT
C1
2.2μF
ENM
ENC
C1P C1M C2P C2M
V_BAT
CPO
LTC3210-2
ENM
ENC
RM
MLED1
MLED2
MLED3
MLED4
CLED
RC
GND
30.1k
1%
24.3k
1%
C4
2.2μF
MAIN
CAM
321023 TA01
4-LED MAIN Display
Efficiency vs V_BAT Voltage
100
90
80
70
60
50
40
30
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)
321023 TA01b
321023fa
1