LT3465/LT3465A
1.2MHz/2.4MHz White LED
Step-Up Converters with
Built-In Schottky in ThinSOT
FEATURES
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DESCRIPTIO
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Inherently Matched LED Current
Drives Up to Six LEDs from a 3.6V Supply
No External Schottky Diode Required
1.2MHz Switching Frequency (LT3465)
2.4MHz Switching Frequency Above AM Broadcast
Band (LT3465A)
Automatic Soft-Start (LT3465)
Open LED Protection
High Efficiency: 81% (LT3465) 79% (LT3465A)
Typical
Requires Only 0.22µF Output Capacitor
Low Profile (1mm) SOT-23 Packaging
The LT
®
3465/LT3465A are step-up DC/DC converters
designed to drive up to six LEDs in series from a Li-Ion cell.
Series connection of the LEDs provides identical LED
currents and eliminates the need for ballast resistors.
These devices integrate the Schottky diode required exter-
nally on competing devices. Additional features include
output voltage limiting when LEDs are disconnected, one-
pin shutdown and dimming control. The LT3465 has
internal soft-start.
The LT3465 switches at 1.2MHz, allowing the use of tiny
external components. The faster LT3465A switches at
2.4MHz. Constant frequency switching results in low input
noise and a small output capacitor. Just 0.22µF is required
for 3-, 4- or 5-LED applications.
The LT3465 and LT3465A are available in low profile
(1mm) 6-lead SOT-23 (ThinSOT
TM
) packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
APPLICATIO S
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Cellular Phones
PDAs, Handheld Computers
Digital Cameras
MP3 Players
GPS Receivers
TYPICAL APPLICATIO
L1
22µH
3V TO 5V
Conversion Efficiency
V
IN
= 3.6V
80 4 LEDs
78
EFFICIENCY (%)
SW
V
IN
SHUTDOWN
AND DIMMING
CONTROL
C1
1µF
LT3465/
LT3465A
CTRL
FB
GND
C2
0.22µF
10Ω
3465A F01a
82
V
OUT
76
74
72
70
68
66
64
62
60
0
5
10
LED CURRENT (mA)
3465A F01b
C1, C2: X5R OR X7R DIELECTRIC
L1: MURATA LQH32CN220
Figure 1. Li-Ion Powered Driver for Four White LEDs
U
LT3465
LT3465A
15
20
3465af
U
U
1
LINER [ LINEAR TECHNOLOGY ]
