V+

GND

LM2665

CAP-

CAP+

OUT

SD

13

LM2665

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SNVS009H – NOVEMBER 1999 – REVISED MARCH 2016

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11 Layout

11.1 Layout Guidelines

The high switching frequency and large switching currents of the LM2665 make the choice of layout important.

Use the following steps as a reference to ensure the device is stable and maintains proper LED current

regulation across its intended operating voltage and current range.

•

Place CIN on the top layer (same layer as the LM2665) and as close to the device as possible. Connecting

the input capacitor through short, wide traces to both the V+ and GND pins reduces the inductive voltage

spikes that occur during switching which can corrupt the V+ line.

•

Place COUT on the top layer (same layer as the LM2665) and as close as possible to the OUT and GND pin.

The returns for both CIN and COUT must come together at one point, as close to the GND pin as possible.

Connecting COUT through short, wide traces reduce the series inductance on the OUT and GND pins that can

corrupt the VOUT and GND lines and cause excessive noise in the device and surrounding circuitry.

•

Place C1 on the top layer (same layer as the LM2665 device) and as close to the device as possible.

Connect the flying capacitor through short, wide traces to both the CAP+ and CAP– pins.

11.2 Layout Example

Figure 17. Typical Layout for LM2665