Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs

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ID 813671
Date 9/17/2025
Public
Document Table of Contents
Document Table of Contents x
1. Agilex™ 5 Clocking and PLL Overview 2. Agilex™ 5 Clocking and PLL Architecture and Features 3. Agilex™ 5 Clocking and PLL Design Considerations 4. Clock Control Altera™ FPGA IP Core 5. IOPLL FPGA IP 6. I/O PLL Reconfiguration 7. Document Revision History for the Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs
1. Agilex™ 5 Clocking and PLL Overview x
1.1. Clock Networks Overview 1.2. PLLs Overview
2. Agilex™ 5 Clocking and PLL Architecture and Features x
2.1. Clock Networks Architecture and Features 2.2. PLLs Architecture and Features
2.1. Clock Networks Architecture and Features x
2.1.1. Clock Network Architecture 2.1.2. Clock Resources 2.1.3. Clock Control Features
2.1.1. Clock Network Architecture x
2.1.1.1. Clock Network Hierarchy 2.1.1.2. Clock Sectors 2.1.1.3. Programmable Clock Routing
2.1.3. Clock Control Features x
2.1.3.1. Clock Gating 2.1.3.2. Clock Divider
2.1.3.1. Clock Gating x
2.1.3.1.1. Root Clock Gate 2.1.3.1.2. Sector Clock Gate 2.1.3.1.3. I/O PLL Clock Gate 2.1.3.1.4. LAB Clock Gate
2.2. PLLs Architecture and Features x
2.2.1. PLL Features 2.2.2. PLL Usage 2.2.3. PLL Locations 2.2.4. PLL Architecture 2.2.5. PLL Control Signals 2.2.6. PLL Feedback Modes 2.2.7. Clock Multiplication and Division 2.2.8. Programmable Phase Shift 2.2.9. Programmable Duty Cycle 2.2.10. PLL Cascading 2.2.11. PLL Input Clock Switchover 2.2.12. PLL Reconfiguration and Dynamic Phase Shift 2.2.13. PLL Calibration
2.2.5. PLL Control Signals x
2.2.5.1. Reset 2.2.5.2. Locked
2.2.6. PLL Feedback Modes x
2.2.6.1. Direct Compensation Mode 2.2.6.2. LVDS Compensation Mode 2.2.6.3. Source Synchronous Compensation Mode 2.2.6.4. Normal Compensation Mode 2.2.6.5. Zero-Delay Buffer Mode 2.2.6.6. External Feedback Mode
2.2.11. PLL Input Clock Switchover x
2.2.11.1. Automatic Switchover 2.2.11.2. Automatic Switchover with Manual Override 2.2.11.3. Manual Clock Switchover
2.2.13. PLL Calibration x
2.2.13.1. Power-Up Calibration 2.2.13.2. User Calibration 2.2.13.3. Static Phase Error Calibration
3. Agilex™ 5 Clocking and PLL Design Considerations x
3.1. Guidelines: Clock Switchover 3.2. Guidelines: Timing Closure 3.3. Guidelines: Resetting the PLL 3.4. Guidelines: Configuration Constraints 3.5. Clocking Constraints 3.6. IP Constraints 3.7. Guideline: Achieving 5% Duty Cycle for fOUT_EXT ≥ 300 MHz Using tx_outclk Port from LVDS SERDES FPGA IP
4. Clock Control Altera™ FPGA IP Core x
4.1. Release Information for Clock Control Altera™ FPGA IP 4.2. Clock Control Altera™ FPGA IP Parameters 4.3. Clock Control Altera™ FPGA IP Ports and Signals
5. IOPLL FPGA IP x
5.1. Release Information for IOPLL FPGA IP 5.2. IOPLL FPGA IP Parameters 5.3. IOPLL IP Ports and Signals
5.2. IOPLL FPGA IP Parameters x
5.2.1. IOPLL IP Parameters - PLL Tab 5.2.2. IOPLL IP Parameters - Settings Tab 5.2.3. IOPLL IP Parameters - Cascading Tab 5.2.4. IOPLL IP Parameters - Advanced Parameters Tab
6. I/O PLL Reconfiguration x
6.1. Implementing HSIO I/O PLL Reconfiguration using EMIF Calibration IP 6.2. Implementing HVIO I/O PLL Reconfiguration 6.3. Address Bus and Data Bus Settings
6.1. Implementing HSIO I/O PLL Reconfiguration using EMIF Calibration IP x
6.1.1. Release Information for EMIF Calibration IP 6.1.2. Setting Up the IOPLL FPGA IP 6.1.3. Setting Up the EMIF Calibration IP 6.1.4. Connectivity Between IOPLL FPGA IP and EMIF Calibration IP 6.1.5. Axilite Interface Ports in the EMIF Calibration IP 6.1.6. Reconfiguration Guideline for HSIO I/O PLLs 6.1.7. Design Example for HSIO I/O PLL Reconfiguration
6.1.6. Reconfiguration Guideline for HSIO I/O PLLs x
6.1.6.1. Enabling Reconfiguration for The Desired I/O PLL 6.1.6.2. Clearing off Calibration Statuses 6.1.6.3. Reconfiguring The I/O PLL 6.1.6.4. Recalibration of I/O PLL 6.1.6.5. Clock Gating (Optional)
6.1.7. Design Example for HSIO I/O PLL Reconfiguration x
6.1.7.1. Reconfiguration Option: Reconfiguration Through EMIF Calibration IP 6.1.7.2. Reconfiguration Option: Clock Gating Reconfiguration
6.2. Implementing HVIO I/O PLL Reconfiguration x
6.2.1. Setting Up the IOPLL FPGA IP 6.2.2. Reconfiguration Guideline for HVIO I/O PLLs 6.2.3. Design Example for HVIO I/O PLL Reconfiguration
6.2.2. Reconfiguration Guideline for HVIO I/O PLLs x
6.2.2.1. Read and Write Operations via Avalon® Memory-Mapped Interface 6.2.2.2. Enabling Reconfiguration for The Desired I/O PLL 6.2.2.3. Clearing off Calibration Statuses 6.2.2.4. Reconfiguring The I/O PLL 6.2.2.5. Enabling Recalibration for HVIO PLLs 6.2.2.6. Requesting Recalibration of I/O PLL 6.2.2.7. Clock Gating (Optional)
6.2.3. Design Example for HVIO I/O PLL Reconfiguration x
6.2.3.1. Reconfiguration Option: Reconfiguration Through EMIF Calibration IP 6.2.3.2. Reconfiguration Option: Clock Gating Reconfiguration
6.3. Address Bus and Data Bus Settings x
6.3.1. Divide Settings and the Corresponding Data Bit Setting for Reconfiguration 6.3.2. Data Bus Setting for Clock Gating Reconfiguration 6.3.3. Data Bus Setting For Charge Pump Current
1. Agilex™ 5 Clocking and PLL Overview
2. Agilex™ 5 Clocking and PLL Architecture and Features
3. Agilex™ 5 Clocking and PLL Design Considerations
4. Clock Control Altera™ FPGA IP Core
5. IOPLL FPGA IP
6. I/O PLL Reconfiguration
7. Document Revision History for the Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs

6.2.2.1. Read and Write Operations via Avalon® Memory-Mapped Interface

The HVIO I/O PLL reconfiguration interface employs a fixed-cycle transaction protocol layered on the Avalon® Memory-Mapped signal set. While the standard Avalon® -MM specification supports variable latencies, this implementation enforces a strict and deterministic cycle timing for all transactions. This design choice ensures simplified timing closure and delivers reliable, predictable operation. Due to the 32-bit data width of the registers, read and write operations to core_avl_readdata[7:0] and core_avl_writedata[7:0] must be split into four separate 8-bit transfers. Each 8-bit segment is transferred sequentially from the least significant to the most significant byte, with each transfer spaced by one clock period.

These timing requirements are unique to the Agilex™ PLL reconfiguration interface and extend beyond the generic Memory-Mapped protocol. They guarantee accurate addressing of internal PLL configuration registers, prevent transaction overlaps by allowing the reconfiguration finite state machine (FSM) to complete cleanly, and maintain a stable, glitch-free PLL output clock throughout the reconfiguration process.

Figure 28. Write Operation Timing Requirements
  1. Start with a 5-Cycle Preamble: After asserting Core_Avl_Write, the Write Data bus must output five consecutive clock cycles of 0x00. These preamble cycles serve as a mandatory initialization phase, allowing the system to align internal buffers and sampling logic. The preamble is not counted as valid payload data.
  2. Transmit Valid Data for the Next 5 Cycles: Immediately following the preamble, place the actual write payload on the bus for five consecutive clock cycles while keeping Core_Avl_Write asserted. The final byte should remain on the bus for an additional cycle to ensure the data is captured within a well-defined and stable timing window.
  3. Observe a 5-Cycle Idle Period After Deassertion: When Core_Avl_Write is deasserted, a minimum of five idle clock cycles must pass before starting another write or read operation. This enforced gap allows internal pipelines to flush and prevents bus contention.
Read transactions also follow a strict timing pattern to account for bus turnaround delays and ensure data stability.
Figure 29. Read Operation Timing Requirements
  1. Ignore the First 5 Cycles of Read Data: Upon asserting Core_Avl_Read, the first five clock cycles of data returned are invalid or undefined and must be discarded. This delay accounts for internal memory access latency and guarantees proper synchronization.
  2. Capture Valid Data Over the Next 5 Cycles: After the initial delay, five consecutive clock cycles of valid read data presents on the bus. The first valid word is always 0x00, followed by the actual requested contents.
  3. Enforce a 5-Cycle Idle Period After Deassertion: Once Core_Avl_Read is deasserted, maintain at least five idle cycles before initiating any new read or write. This prevents overlapping between transactions and avoids data corruption
Note: The PLL may lose lock and cause reliability problems for your device if you configure it with the wrong PLL setting, configure the wrong bit, or overwrite the whole byte for settings that make up just part of one byte.
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