E-Tile Transceiver PHY User Guide

ID 683723
Date 9/30/2022
Public
Document Table of Contents

4.1.1. QSF Assignments for Reference Clock Pins

Refer to the Device Family Pin Connection Guidelines for how to connect unused reference clock pins.
Table 54.  QSF Assignments for a Single Reference Clock Pin (refclk[0])You must manually include these QSF settings for every used reference clock pin.
Description Value QSF Assignment
Set reference clock IO standard differential LVPECL set_instance_assignment -name IO_STANDARD "DIFFERENTIAL LVPECL" -to <refclk_name> -entity <block_name>
Enable on-die termination resistors

enable_term = (on-chip termination on)

disable_term = (on-chip termination off)

set_instance_assignment -name HSSI_PARAMETER "refclk_divider_enable_termination=enable_term" -to ref_clk[0]

Recommendation: Set this to enable_term unless external on-board termination is used and internal termination is supposed to be bypassed.

Select 3.3 V tolerant instead of 2.5 V

enable_3p3v_tol = (3.3V)

disable_3p3v_tol = (2.5V)

set_instance_assignment -name HSSI_PARAMETER "refclk_divider_enable_3p3v=enable_3p3v_tol" -to ref_clk[0] 35

Recommendation: Set this to disable_3p3v_tol unless the clock source is compliant to LVPECL 3.3v standard.

Enable LVPECL driver hysteresis

enable_hyst = (hysteresis on)

disable_hyst = (hysteresis off)

set_instance_assignment -name HSSI_PARAMETER "refclk_divider_disable_hysteresis=enable_hyst" -to ref_clk[0]

Recommendation: Set this to disable_hyst provided that the reference clock characteristic meets the specification in the Device Data Sheet.

Set reference clock frequency freq_in_Hz = "legal value" set_instance_assignment -name HSSI_PARAMETER "refclk_divider_input_freq=freq_in_Hz" -to ref_clk[0]

Recommendation: Use the same reference clock frequency number as in the respective transceiver IP.

Power down LVPECL driver

false = (driver on)

true = (driver off)

set_instance_assignment -name HSSI_PARAMETER "refclk_divider_powerdown_mode=false" -to ref_clk[0]

Recommendation: If you plan to use the target reference clock, set this to false.

35 Refer to the Device Data Sheet for the reference clock voltage rating electrical specifications.
36 Refer to the Device Data Sheet for the reference clock frequency specification.

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