LT3466 Linear Technology, LT3466 Datasheet - Page 13

• Manufacturer Part Number: LT3466
• Description: Dual Full Function White LED Step-Up Converter with Built-In Schottky Diodes
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
Figure 9 shows four LEDs being run off two AA cells. The
battery is connected to the inductors and the chip is
powered off 3.3V logic supply voltage.
HIGH INPUT VOLTAGE APPLICATIONS
The input voltage to LT3466 can be as high as 24V. This
gives it the flexibility of driving a large number of LEDs
when being run off a higher voltage. The maximum num-
ber of LEDs that can be driven is constrained by the
converter output voltages being clamped at 42V.
The LT3466 can be used to power 20 White LEDs (10 per
converter) at 20mA when running off two Li-Ion cells in
series.
2 AA CELLS
1.8V to 3V
Figure 9. 2 AA Cells to Four White LEDs
10
1 F
1 F
U
15 H
L1
V
FB1
CTRL1
SW1
OUT1
U
LT3466
V
R
IN
T
63.4k
1%
CTRL2
V
SW2
OUT2
FB2
W
L2
15 H
0.1 F
1 F
3.3V
U
10
3466 F09
BOARD LAYOUT CONSIDERATION
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To prevent electromagnetic interference (EMI) problems,
proper layout of high frequency switching paths is essen-
tial. Minimize the length and area of all traces connected to
the switching node pins (SW1 and SW2). Keep the feed-
back pins (FB1 and FB2) away from the switching nodes.
The DFN package has an exposed paddle that must be
connected to the system ground. The ground connection
for the feedback resistors should be tied directly to the
ground plane and not shared with any other component,
except the R
nection. Recommended component placement is shown
in the Figure 10.
C
IN
GND
GND
V
IN
Figure 10. Recommended Component Placement
L1
L2
C
C
OUT1
OUT2
T
resistor, ensuring a clean, noise-free con-
1
2
3
4
5
11
10
9
8
7
6
R
R
FB1
FB2
LT3466
R
T
13
CTRL1
CTRL2
3466 F10
3466f