SNAA408 April   2025 LMK3H0102

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Output Recommendations
    1. 2.1 Differential vs. Single-Ended
    2. 2.2 Slew Rate
    3. 2.3 Spread Spectrum Clocking
  6. 3PCB Design
    1. 3.1 Stackup
    2. 3.2 Power Filtering
    3. 3.3 Avoid Bottlenecking
    4. 3.4 Strategic Via Placements
      1. 3.4.1 Distributing Power Concentrations
        1. 3.4.1.1 Via Sizes
        2. 3.4.1.2 Pads and Pours
      2. 3.4.2 Shielding and Stitching Vias
  7. 4Minimize Possible Antennas
    1. 4.1 Stubs
    2. 4.2 Net Pours
  8. 5Summary
  9. 6References

3.4.1.2 Pads and Pours

A large passive component pad connecting to a smaller trace width can also be a source of EMI spikes (Figure 3-8). When connecting the passives, have the trace width match the pad size. Similarly, when connecting a net between two planes, use several vias to distribute the energy more evenly (Figure 3-9). This is especially crucial for power and ground nets.


Large Passive with Few Vias

Figure 3-8 Large Passive with Few Vias

Large Passive with Many Vias

Figure 3-9 Large Passive with Many Vias