SPRADI2 March   2025 AM62L

 

  1.   1
  2.   Trademarks
  3. 1 Introduction
  4. 2 Via Channel Arrays
  5. 3 Width/Spacing Proposal for Escapes
  6. 4 Stackup
  7. 5 Via Sharing
  8. 6 Floorplan Component Placement
  9. 7 Critical Interfaces Impact Placement
  10. 8 Routing Priority
  11. 9 SerDes Interfaces
  12. 10DDR Interfaces
  13. 11Power Decoupling
  14. 12Route Lowest Priority Interfaces Last
  15. 13Summary
  16. 14Revision History

11 Power Decoupling

The middle priority interfaces and the power distribution planes and pours are routed next after the SerDes and DDR interfaces. It is strongly encouraged to complete all SerDes and DDR routing before continuing with other interfaces. The power distribution planes and pours and all of the decoupling must be placed before PCB simulations are executed for the SerDes and DDR routes, as these can influence the return currents for the high-speed interfaces. The highest speed source-synchronous interfaces, such as RGMII and OSPI, may also require simulation so these may need to be completed at this time as well.

Special care is needed for the 1uF output capacitors connected to the CAP_VDDS* BGA pins on the AM62Lx device. These capacitors should be placed as close to the pin as possible, and a low inductance path should be present between the CAP_VDDS BGA pin and the supply pad on the capacitor.

This placement can be improved if the capacitors can be placed directly under the SoC. The decoupling capacitors for the VDD_CORE and VDDS_DDR supplies should also receive the same priority as those on the CAP_VDDS* pins and should be placed under the socket, with minimum inductance connections to the respective BGA pins on the AM62Lx device.