LT3486
Dual 1.3A White LED
Step-Up Converters with
Wide Dimming
FEATURES
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DESCRIPTIO
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Wide (1000:1) PWM Dimming Range with No
ColorShift
Independent Dimming and Shutdown Control of the
LED Drivers
Drives Up to 16 White LEDs at 25mA (8 per Driver)
from a Single Li-Ion Cell
Drives Up to 16 White LEDs at 100mA (8 per Driver)
from 12V Supply
±3% LED Current Programming Accuracy
Open LED Protection: 36V Clamp Voltage
Fixed Frequency Operation: Up to 2MHz
Wide Input Voltage Range: 2.5V to 24V
Low Shutdown Current: I
CC
< 1µA
Overtemperature Protection
Available in (5mm
×
3mm
×
0.75mm) 16-Pin DFN
and 16-Pin Thermally Enhanced TSSOP Packages
The LT
®
3486 is a dual step-up DC/DC converter
specifically designed to drive up to 16 White LEDs (8 in
series per converter) at constant current from a single
Li-Ion cell. Series connection of the LEDs provides identi-
cal LED currents resulting in uniform brightness. The two
independent converters are capable of driving asymmetric
LED strings.
The dimming of the two LED strings can be controlled
independently via the respective CTRL pins. An internal
dimming system allows the dimming range to be extended
up to 1000:1 by feeding a PWM signal to the respective
PWM pins. The LT3486 operating frequency can be set with
an external resistor over a 200kHz to 2MHz range. A low
200mV feedback voltage (±3% accuracy) minimizes power
loss in the current setting resistor for better efficiency.
Additional features include output voltage limiting when
LEDs are disconnected and overtemperature protection.
The LT3486 is available in a space saving 16-pin DFN
(5mm
×
3mm
×
0.75mm) and 16-pin thermally enhanced
TSSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patent Pending.
APPLICATIO S
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Notebook PC Display
LED Camera Light for Cell Phones
Car Dashboard Lighting
Avionics Displays
TYPICAL APPLICATIO
Li-Ion Powered Driver for Camera Flash and LCD Backlighting
V
IN
3V TO 4.2V
10µF
2.2µF
LED1
AOT3218
DIMMING 1
OFF ON
SW1
OVP1
CTRL1
SHDN
PWM1
OFF ON
R
FB1
0.62Ω
0.1µF
FB1
V
C1
100k
R
T
63.4k
LT3486
L1
10µH
V
IN
L2
10µH
SW2
OVP2
CTRL2
REF
PWM2
FB2
V
C2
2.8k
4.7nF
R
FB2
8.06Ω
3486 TA01a
90
2.2µF
8 LEDs
EFFICIENCY (%)
MOVIE MODE
I
LED1
= 175mA
85
FLASH MODE
I
LED1
= 320mA
DIMMING 2
25mA
80
75
0.1µF
70
8 LEDS/25mA
3
3.2
3.4
3.6
V
IN
(V)
3.8
4
4.2
65
U
Efficiency vs V
IN
3486 TA01b
U
U
3486f
1
LINER [ LINEAR TECHNOLOGY ]
