2.2.3 PLL Reference Clock Source and Frequency

The following sources are available from the reference clock menu.

• Dedicated Input Pad—The clock source is one of the four regular FPGA I/Os that have a dedicated path to the CCC.
• Fabric Input—The clock source is one of the four signals coming from the FPGA Fabric:
  • FPGA Fabric Input 0
  • FPGA Fabric Input 1
  • FPGA Fabric Input 2
  • FPGA Fabric Input 3
• Oscillators—The source is from the 50 MHz on-chip oscillator. The RCOSC_50MHZ macro must be manually instantiated and connected to the CCC input pin if selected as the reference clock source.