Source Termination Attribute (OUTPUT_IMPEDANCE) - Source Termination Attribute (OUTPUT_IMPEDANCE) - UG861

Spartan UltraScale+ FPGAs SelectIO Resources User Guide (UG861)

Document ID
UG861
Release Date
2026-04-28
Revision
1.1 English

The OUTPUT_IMPEDANCE attribute (HP and XP5IO I/O banks only) provides the option of choosing the driver impedance for HSTL, SSTL, HSUL, LVDCI, HSLVDCI, and POD drivers to match the characteristic impedance of the driven line. The OUTPUT_IMPEDANCE attribute is used to define the value of source termination at the driver for both DCI and non-DCI versions of the standards supported.

Allowed values for the OUTPUT_IMPEDANCE attribute:

  • RDRV_40_40
  • RDRV_48_48
  • RDRV_60_60
  • RDRV_NONE_NONE
Note: Not all values are allowed for all applicable I/O standards and configurations.

The XDC syntax for this attribute is:

set_property OUTPUT_IMPEDANCE value [get_ports port_name ]