1.9 Designing for High-Speed Peripherals

The PIC32C Family of devices have peripherals that operate at frequencies much higher than typical for an embedded environment. The following list shows the peripherals that produce high-speed signals on their external pins on this device:

USB
SPI (Sercom)

Due to these high-speed peripheral signals, it is important to consider several factors when designing a product that uses these peripherals, as well as the PCB on which these components will be placed. Adhering to these recommendations will help achieve the following goals:

Minimize the effects of electromagnetic interference for the proper operation of the product.
Run all PCB high-speed signals first on component side of PCB.
Ensure signals arrive at their intended destination at the same time by matching critical trace lengths on the PCB.
Minimize crosstalk. Insure continuous ground under all high-speed signals.
Maintain signal integrity by the use of termination resistors in the 30-50 Ω range.
Reduce system noise by using bulk and high frequency decoupling caps and inductors on power rails.
Minimize ground bounce and power sag. Use a dedicated ground plane if possible or at a minimum a star ground configuration. Do not daisy chain ground and power traces to components.