General-Purpose I/O User Guide: Agilex™ 3 FPGAs and SoCs
ID
847266
Date
8/04/2025
Public
Visible to Intel only — GUID: ifa1550711418102
Ixiasoft
1. Agilex™ 3 General-Purpose I/O Overview
2. Agilex™ 3 HSIO Banks
3. Agilex™ 3 HVIO Banks
4. Agilex™ 3 HPS I/O Banks
5. Agilex™ 3 SDM I/O Banks
6. Agilex™ 3 I/O Troubleshooting Guidelines
7. GPIO FPGA IP
8. Programmable I/O Features Description
9. Document Revision History for the General-Purpose I/O User Guide: Agilex™ 3 FPGAs and SoCs
2.5.1. I/O Standard Placement Restrictions for True Differential I/Os
2.5.2. Placement Restrictions for True Differential and Single-Ended I/O Standards in the Same or Adjacent HSIO Bank
2.5.3. VREF Sources and Input Standards Grouping
2.5.4. HSIO Pin Restrictions for External Memory Interfaces
2.5.5. RZQ Pin Requirement
2.5.6. I/O Standards Implementation Based on VCCIO_PIO Voltages
2.5.7. I/O Standard Selection and I/O Bank Supply Compatibility Check
2.5.8. Simultaneous Switching Noise
2.5.9. HPS Shared I/O Requirements
2.5.10. Clocking Requirements
2.5.11. Clock Restrictions for GPIO Interfaces
2.5.12. SDM Shared I/O Requirements
2.5.13. Unused Pins
2.5.14. VCCIO_PIO Supply for Unused HSIO Banks
2.5.15. HSIO Pins During Power Sequencing
2.5.16. Drive Strength Requirement for HSIO Input Pins
2.5.17. Maximum DC Current Restrictions
2.5.18. 1.05 V, 1.1 V, or 1.2 V I/O Interface Voltage Level Compatibility
2.5.19. Connection to True Differential Signaling Input Buffers During Device Reconfiguration
2.5.20. Implementing a Pseudo Open Drain
2.5.21. Allowed Duration for Using RT OCT
2.5.22. Single-Ended Strobe Signal Differential Pin Pair Restriction
2.5.23. Implementing SLVS-400 or DPHY I/O Standard with 1.1 V VCCIO_PIO
Visible to Intel only — GUID: ifa1550711418102
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2.4.2.2. True Differential Signaling I/O Standard External Termination
Analyze the electrical specification requirement of the LVDS interface and ensure the common-mode voltage for your LVDS data rate conforms to the data sheet specification.
- Use AC coupling and external voltage bias circuitry if the common-mode voltage of the output buffer does not match the differential receiver input common-mode voltage.
- Consider using a dedicated VICM voltage supply for wide LVDS interfaces that share a common VICM reference voltage.
Note: Altera recommends that you use SPICE or IBIS models to verify your AC- or DC-coupled termination.
Figure 19. Example of AC-Coupled External VICM Termination
Figure 20. Example of AC-Coupled External Termination for 1.3 V VCCIO_PIO