Arria 10 GX Transceiver Signal Integrity Development Kit User Guide

ID 683553
Date 8/08/2017
Public
Document Table of Contents

5.7.2. General Purpose Clocks

In addition to the transceiver dedicated clocks, five other clock sources will be provided to the FPGA Global CLK inputs for general FPGA design as shown in the figure below

The usage of these clocks is as follows:
  1. 50 MHz oscillator through an ICS8304 buffer for Nios® II applications. This clock is also routed to the MAX V device for configuration.
  2. 25 MHz crystal supplied to an ICS557-03 Spread Spectrum differential clock buffer. The available frequencies and down spread percentages available from the spread spectrum buffer as shown in the table below
  3. External differential clock source from SMA connectors.
  4. Four 100 MHz clock outputs are provided from an SiLabs Si5338A-Custom clock buffer.
    • CLK0: 100MHz- LVDS standard
    • CLK1: 100MHz- LVDS standard
    • CLK2: 100MHz- 1.8V CMOS standard
    • CLK3: 100MHz- LVDS standard
  5. One 125 MHz LVDS standard Oscillator output.
Figure 10. General Purpose FPGA Clocks
Table 9.  Spread Spectrum Clock Settings and frequencies
Spread Spectrum Buffer (inputs) Output Clock Select Spread (%)
SS1/S1 SS0/S0  
0 0 25 MHz (Default) Center +/- 0.25
0 1 100 MHz Down -0.5
1 0 125 MHz Down -0.75
1 1 200 MHz No Spread