INTERNAL_VREF - 2023.2 English

Vivado Design Suite Properties Reference Guide (UG912)

Document ID
Release Date
2023.2 English

Single-ended I/O standards with a differential input buffer require an input reference voltage (VREF). When VREF is required within an I/O bank, you can use the dedicated VREF pin as an external VREF supply, or an internally generated VREF using the INTERNAL_VREF property, or for HP I/O banks on UltraScale devices use the VREF scan accessed through the HPIO_VREF primitive.

The INTERNAL_VREF property specifies the use of an internal regulator on an I/O bank to supply the voltage reference (VREF) for I/O standards requiring a reference voltage. Internally generated reference voltages remove the need to provide a particular VREF through a supply rail on the printed circuit board (PCB). This can reduce routing congestion on the system-level design.

Tip: Consider using the Internal Vref when the AMD device is the only device on the board/system requiring a particular VREF voltage supply level.

Refer to 7 Series FPGAs SelectIO Resources User Guide (UG471) or to UltraScale Architecture SelectIO Resources User Guide (UG571) for more information.

Architecture Support
All architectures.
Applicable Objects
I/O Bank (get_iobanks)
  • 0.60
  • 0.675
  • 0.7 (UltraScale only)
  • 0.75
  • 0.84 (UltraScale only)
  • 0.90
Note: Not all values are supported in all types of I/O banks.


Verilog Syntax

Not applicable

VHDL Syntax

Not applicable

XDC Syntax
set_property INTERNAL_VREF {value} [get_iobanks bank]

Where value is the reference voltage value.

XDC Syntax Example:

# Designate Bank 14 to have a reference voltage of 0.75 Volts 
set_property INTERNAL_VREF 0.75 [get_iobanks 14]

Affected Steps

  • I/O planning
  • Place Design
  • DRC
  • report_power