11.1 Layout Guidelines

The high switching frequency and large switching currents of the LM2660 make the choice of layout important. The following steps should be used as a reference to ensure the device is stable and maintains proper LED current regulation across its intended operating voltage and current range:

• Place C_IN on the top layer (same layer as the LM2660) 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 C_OUT on the top layer (same layer as the LM2660) and as close as possible to the OUT and GND pin. The returns for both C_IN and C_OUT should come together at one point, as close to the GND pin as possible. Connecting C_OUT through short, wide traces reduce the series inductance on the OUT and GND pins that can corrupt the V_OUT and GND lines and cause excessive noise in the device and surrounding circuitry.
• Place C₁ on the top layer (same layer as the LM2660) 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 25. LM2660 Layout Example