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LT3465A

2.4MHz White LED Step-Up Converter with Built-In Schottky in ThinSOT™

Linear Technology 

LT3465A

APPLICATIO S I FOR ATIO

Open Circuit Protection

The LT3465A has an internal open-circuit protection cir-

cuit. When the LEDs are disconnected from the circuit or

fail open, VOUT is clamped at 30V. The LT3465A will then

switch at a low frequency, minimizing input current. VOUT

and input current during open circuit are shown in the

Typical Performance Characteristics.

Board Layout Consideration

As with all switching regulators, careful attention must be

paid to the PCB board layout and component placement.

To maximize efficiency, switch rise and fall times are made

as short as possible. To prevent electromagnetic interfer-

ence (EMI) problems, proper layout of the high frequency

switching path is essential. Place COUT next to the VOUT

pin. Always use a ground plane under the switching

regulator to minimize interplane coupling. In addition, the

ground connection for the feedback resistor R1 should be

tied directly to the GND pin and not shared with any other

component, ensuring a clean, noise-free connection. Rec-

ommended component placement is shown in Figure 7.

Start-Up Input Current

As previously mentioned, the LT3465A does not have an

internal soft-start circuit. Inrush current can therefore rise

to approximately 400mA as shown in Figure 8 when

driving 4 LEDs. The LT3465 has an internal soft-start

circuit and is recommended if inrush current must be

minimized.

COUT

1

2

RFB

3

GND

L

6

5

4

CIN

VIN

3465 F07

CTRL

Figure 7. Recommended Component Placement

IIN

200mV/DIV

FB

200mV/DIV

CTRL

2V/DIV

50µs/DIV

Figure 8.

3465A F06b

3465ai

8

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