LTH2 Marking, LT3465 datasheet(12/16 Pages) LINER

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LT3465/LT3465A

3465afa

APPLICATIO S I FOR ATIO

Figure 9.

Open-Circuit Protection

The LT3465 and LT3465A have an internal open-circuit

protection circuit. In the cases of output open circuit,

when the LEDs are disconnected from the circuit or the

LEDs fail, the VOUT is clamped at 30V. The LT3465 and

LT3465A will then switch at a very low frequency to

minimize the input current. VOUT and input current during

output 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

interference (EMI) problems, proper layout of the high

frequency switching path is essential. Place COUT next to

the VOUT and GND pins. 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. Recommended component placement is

shown in Figure 8.

Start-Up Input Current (LT3465A)

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 9 when

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

circuit and is recommended if inrush current must be

minimized.

Figure 8. Recommended Component Placement.

COUT

RFB

CIN

GND

3465A F08a

VIN

CTRL

200mV/DIV

CTRL

2V/DIV

µs/DIV

3465A F09

IIN

200mV/DIV

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