LT3466 Ver la hoja de datos (PDF) - Linear Technology
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LT3466 Datasheet PDF : 20 Pages
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LT3466
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.
2 AA CELLS
1.8V to 3V
1µF L1
15µH
L2
15µH
3.3V
0.1µF
SW1 VIN SW2
VOUT1
VOUT2
1µF
LT3466
1µF
FB1
FB2
CTRL1 RT CTRL2
10Ω
OFF ON
OFF ON
63.4k
1%
10Ω
3466 F09
Figure 9. 2 AA Cells to Four White LEDs
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 RT resistor, ensuring a clean,
noise-free connection. Recommended component place-
ment for the DFN package is shown in Figure 10.
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
GND
COUT1
when being powered off a higher voltage. The maximum
number of LEDs that can be driven is constrained by the CIN L1
1
converter output voltages being clamped at 39.5V (typ).
2
RFB1
10
9
CTRL1
RT
The LT3466 can be used to drive 20 White LEDs (10 per
VIN L2
3
11
8
4
7
converter) at 20mA when powered off two Li-Ion cells in
5
6
CTRL2
series.
RFB2
GND
COUT2
3466 F10
Figure 10. Recommended Component Placement (DFN Package)
3466fa
13
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