For best performance, TI recommends the following:
- Two power planes
- One solid plane for ground (GND)
- One split plane for other voltages with no signal routing on the power planes
- Power and ground pins should be connected to these planes through a via for each pin.
- All device pin and via connections to these planes should use a thermal relief with a minimum of four spokes.
- Trace lengths for the component power and ground pins should be minimized to 0.03 inches or less.
- Vias should be spaced out to avoid forming slots on the power planes.
- High speed signals should not cross over a slot in the adjacent power planes.
- Vias connecting all the digital layers should be placed around the edge of the rigid PCB regions 0.03 inches from the board edges with 0.1 inch spacing prior to routing.
- Placing extra vias is not required if there are sufficient ground vias due to normal ground connections of devices.
- All signal routing and signal vias should be inside the perimeter ring of ground vias.