SNVSB29C October 2018 – June 2021 LM5143-Q1
As mentioned previously, using one or more of the inner PCB layers as a solid ground plane is recommended. A ground plane offers shielding for sensitive circuits and traces and also provides a quiet reference potential for the control circuitry. Connect the PGND1 and PGND2 pins to the system ground plane using an array of vias under the exposed pad. Also connect the PGND1 and PGND2 pins directly to the return terminals of the input and output capacitors. The PGND nets contain noise at the switching frequency and can bounce because of load current variations. The power traces for PGND1/2, VIN and SW1/2 can be restricted to one side of the ground plane. The other side of the ground plane contains much less noise and is ideal for sensitive analog trace routes.