LT3466EFE Linear Technology, LT3466EFE Datasheet - Page 13

• Manufacturer Part Number: LT3466EFE
• Description: IC,Laser Diode/LED Driver,TSSOP,16PIN,PLASTIC
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
Figure 9 shows four LEDs being powered 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 the LT3466 can be as high as 24V. This
gives it the flexibility of driving a large number of LEDs
when being powered off a higher voltage. The maximum
number of LEDs that can be driven is constrained by the
converter output voltages being clamped at 39.5V (typ).
The LT3466 can be used to drive 20 White LEDs (10 per
converter) at 20mA when powered off two Li-Ion cells in
series.
2 AA CELLS
1.8V to 3V
Figure 9. 2 AA Cells to Four White LEDs
10Ω
1µF
1µF
OFF ON
U
15µH
L1
V
FB1
CTRL1
SW1
OUT1
U
LT3466
V
R
IN
T
63.4k
1%
CTRL2
V
SW2
OUT2
FB2
W
L2
15µH
OFF ON
0.1µF
1µF
3.3V
U
10Ω
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 exposed paddle for both DFN and TSSOP packages
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
noise-free connection. Recommended component place-
ment for the DFN package is shown in Figure 10.
Figure 10. Recommended Component Placement (DFN Package)
C
IN
GND
GND
V
IN
L1
L2
C
C
OUT1
OUT2
1
2
3
4
5
11
T
resistor, ensuring a clean,
10
9
8
7
6
R
R
FB1
FB2
LT3466
R
T
13
CTRL1
CTRL2
3466 F10
3466fa