General-Purpose I/O User Guide: Agilex™ 3 FPGAs and SoCs

ID 847266
Date 8/04/2025
Public
Document Table of Contents

2.5.3. VREF Sources and Input Standards Grouping

Consider these VREF sources guidelines.

Agilex™ 3 devices support internal VREF sources. Each I/O lane in the bank also has its own internal VREF generator. You can configure VREF generator in the External Memory Interfaces (EMIF) IP and PHY Lite for Parallel Interfaces IP.

In each I/O lane, adhere to the input standards grouping to ensure all input pins in the I/O lane use the same internal VREF source. If the mix of input standards in an I/O lane does not adhere to these groupings, Quartus® Prime displays error messages during design compilation.

Note: Although the following table lists the groups based on VREF, the final rules depend on implementation. For example, the PHY Lite interface uses one I/O standard per I/O lane. If you use HSTL-12 and SSTL-12 with the PHY Lite for Parallel Interfaces IP, assign each I/O standard in a different I/O lane.
Table 20.  Input Standards Groups Per I/O Lane
Group Input Standards Mix within I/O Lane
Group 1
  • POD12
  • 1.2 V True Differential Signaling
  • 1.2 V LVCMOS
  • Differential POD12
Group 2
  • POD11
  • 1.1 V True Differential Signaling
  • 1.1 V LVCMOS
  • Differential POD11
Group 3
  • SSTL-12
  • HSTL-12
  • HSUL-12
  • 1.2 V True Differential Signaling
  • 1.2 V LVCMOS
  • Differential SSTL-12
  • Differential HSTL-12
  • Differential HSUL-12
Group 4
  • LVSTL11
  • 1.1 V LVCMOS
  • Differential LVSTL11
Group 5
  • LVSTL105
  • 1.05 V LVCMOS
  • Differential LVSTL105