LT3466 datasheet(13/20 Pages) LINER

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LT3466

3466f

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.

CTRL1

CTRL2

SW1

SW2

VIN

LT3466

VOUT1

63.4k

3466 F09

FB1

Ω

VOUT2

FB2

µH

2 AA CELLS

1.8V to 3V

µF

µH

0.1

µF

3.3V

µF

Ω

Figure 9. 2 AA Cells to Four White LEDs

COUT1

RFB1

CTRL1

CTRL2

3466 F10

RFB2

COUT2

CIN

VIN

GND

Figure 10. Recommended Component Placement

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.

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 RT resistor, ensuring a clean, noise-free con-

nection. Recommended component placement is shown

in the Figure 10.

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