LTC3216 Datasheet, PDF (1/12 Pages) Linear Technology – 1A Low Noise High Current LED Charge Pump with Independent Torch/Flash Current Control

LTC3216
1A Low Noise High Current
LED Charge Pump with
Independent Torch/Flash Current Control
FEATURES
s _{High Efficiency Operation: 1x, 1.5x or 2x Boost}
Modes with Automatic Mode Switching
s _{Ultralow Dropout ILED Current Control}
s _{Output Current up to 1A}
s _{Low Noise Constant Frequency Operation*}
s _{Independent Low Current/High Current}
Programming and Enable Pins
s _{Wide VIN Range: 2.9V to 4.4V}
s _{Open/Shorted LED Protection}
s _{LED Disconnect in Shutdown}
s _{Low Shutdown Current: 2.5µA}
s _{4% LED Current Programming Accuracy}
s _{Automatic Soft-Start Limits Inrush Current}
s _{No Inductors}
s _{Tiny Application Circuit (All Components <1mm}
Profile)
s _{3mm × 4mm 12-ULead DFN Package}
APPLICATIO S
s _{LED Torch/Camera Light Supply for Cell Phones,}
PDAs and Digital Cameras
s _{Generic Lighting and/or Flash/Strobe Applications}
DESCRIPTIO
The LTC^®3216 is a low noise, high current charge pump
DC/DC converter designed to power high current LEDs.
The part includes an accurate programmable current
source capable of driving loads up to 1A from a 2.9V to
4.4V input. Low external parts count (two flying capaci-
tors, two programming resistors and two bypass capaci-
tors at V_IN and CPO) make the LTC3216 ideally suited for
small, battery-powered applications.
Built-in soft-start circuitry prevents excessive inrush cur-
rent during start-up. High switching frequency enables the
use of small external capacitors. Independent high and
low current settings are programmed by two external
resistors. Shutdown mode and current output levels are
selected via two logic inputs.
An ultralow dropout current source maintains accurate
LED current at very low I_LED voltages. Automatic mode
switching optimizes efficiency by monitoring the voltage
across the LED current source and switching modes only
when I_LED dropout is detected. The LTC3216 is available in
a small 3mm × 4mm 12-Lead DFN package.
, 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.
TYPICAL APPLICATIO
C1
2.2µF
C2
2.2µF
2.9V TO 4.4V
C_IN
2.2µF
EN1 (TORCH)
EN2 (FLASH)
C1⁺ C1^– C2⁺ C2^–
V_IN
CPO
LTC3216
LED1
C_CPO
4.7µF
I_LED
EN1
EN2
I_SET1 I_SET2
20k 6.65k
1% 1%
EN1 EN2
0
0
1
0
0
1
1
1
LED1: LUMILEDS LXCL-PWF1 LUXEON FLASH
I_LED
0 (SHUTDOWN)
200mA (TORCH)
600mA
800mA (FLASH)
3216 TA01a
Torch Mode Efficiency vs V_IN
100
90
I_LED = 200mA
80
70
60
50
40
30
20
P_LED/PIN
10
LUMILEDS LXCL-PWF1
V_F = 3V TYP AT 200mA
0
2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
V_IN (V)
3216 TA01b
3216fa
1