LT3466 Datasheet, PDF (1/20 Pages) Linear Technology – Dual Full Function White LED Step-Up Converter with Built-In Schottky Diodes

FEATURES
■ _{Drives Up to 20 White LEDs (10 in Series}
per Converter) from a 3.6V Supply
■ _{Two Independent Step-Up Converters Capable of}
Driving Asymmetric LED Strings
■ _{Independent Dimming and Shutdown Control}
of the Two LED Strings
■ _{Internal Schottky Diodes}
■ _{Internal Soft-Start Eliminates Inrush Current}
■ _{Open LED Protection (39.5V Max VOUT)}
■ _{Fixed Frequency Operation Up to 2MHz}
■ _{81% Efficiency Driving 16 White LEDs at 15mA}
(Eight per Driver) from a 3.6V Supply
■ _{Wide Input Voltage Range: 2.7V to 24V}
■ _{Available in 10-Pin DFN and 16-Pin Thermally}
Enhanced TSSOP Packages
U
APPLICATIO S
■ _{Main/Sub Displays}
■ _{Digital Cameras, Sub-Notebook PCs}
■ _{PDAs, Handheld Computers}
■ _Automotive
LT3466
Dual Full Function White LED
Step-Up Converter with
Built-In Schottky Diodes
DESCRIPTIO
LT^®3466 is a dual full function step-up DC/DC converter
specifically designed to drive up to 20 White LEDs (10 in
series per converter) with a constant current. Series
connection of the LEDs provides identical LED currents
resulting in uniform brightness and eliminating the need
for ballast resistors and expensive factory calibration.
The two independent converters are capable of driving
asymmetric LED strings. The dimming of the two LED
strings can also be controlled independently. The LT3466
is ideal for providing backlight for main and sub-displays
in cell phones and other handheld devices.
The LT3466 operating frequency can be set with an
external resistor over a 200kHz to 2MHz range. A low
200mV feedback voltage minimizes power loss in the
current setting resistor for better efficiency. Additional
features include output voltage limiting when LEDs are
disconnected and internal soft-start.
The LT3466 is available in the 10-pin (3mm × 3mm ×
0.75mm) DFN and 16-pin thermally enhanced TSSOP
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
3V TO 5V
1µF
L1
47µH
L2
47µH
LED1
2.2µF
SW1 V_IN
V_OUT1
SW2
V_OUT2
LT3466
2.2µF
LED2
FB1
FB2
CTRL1 RT GND CTRL2
10Ω
OFF ON ^63.4k
SHUTDOWN
AND DIMMING
CONTROL 1
OFF ON
SHUTDOWN
AND DIMMING
CONTROL 2
10Ω
3466 F01a
Figure 1. Li-Ion Powered Driver for 8/8 White LEDs
Conversion Efficiency
85
V_IN = 3.6V
8/8 LEDs
80
75
70
65
60
55
50
0
5
10
15
LED CURRENT (mA)
20
3466 F01b
3466fa
1