Recommended PCB Iayout

AN3302

4/13

Doc ID 18163 Rev 1

2

Recommended PCB Iayout

2.1

Layout considerations

The layout is an important design step for all switching power supplies due to the high

switching frequency and peak current. If the layout is not performed carefully, important

parameters such as efficiency and output voltage ripple may be out of specification.

Short, wide traces must be implemented for the main current and for power ground paths.

The input capacitor must be placed as close as possible to the IO pins as well as the

inductor and output capacitor.

The feedback pin (FB) connection to the external resistor divider is a high impedance node,

so interference can be minimized by placing the routing of the feedback node as far as

possible from the high current paths. To reduce pick-up noise, the resistor divider must be

placed very close to the device.

A common ground node minimizes ground noise. The exposed pad of the package must be

connected to the common ground node.

Figure 3.

Recommended PCB layout

AM07857v1

AM07857v1