External Memory Interface Handbook Volume 2: Design Guidelines: For UniPHY-based Device Families

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ID 683385
Date 3/06/2023
Public
Document Table of Contents
Document Table of Contents x
1. Planning Pin and FPGA Resources 2. DDR2 and DDR3 SDRAM Board Design Guidelines 3. Dual-DIMM DDR2 and DDR3 SDRAM Board Design Guidelines 4. LPDDR2 SDRAM Board Design Guidelines 5. RLDRAM II and RLDRAM 3 Board Design Guidelines 6. QDR II/II+ SRAM Board Design Guidelines 7. Implementing and Parameterizing Memory IP 8. Simulating Memory IP 9. Analyzing Timing of Memory IP 10. Debugging Memory IP 11. Optimizing the Controller 12. PHY Considerations 13. Power Estimation Methods for External Memory Interfaces
1. Planning Pin and FPGA Resources x
1.1. Interface Pins 1.2. Guidelines for UniPHY-based External Memory Interface IP 1.3. Using PLL Guidelines 1.4. PLL Cascading 1.5. DLL 1.6. Other FPGA Resources 1.7. Document Revision History
1.1. Interface Pins x
1.1.1. Estimating Pin Requirements 1.1.2. DDR, DDR2, and DDR3 SDRAM Clock Signals 1.1.3. DDR, DDR2, and DDR3 SDRAM Command and Address Signals 1.1.4. DDR, DDR2, and DDR3 SDRAM Data, Data Strobes, DM/DBI, and Optional ECC Signals 1.1.5. DDR, DDR2, and DDR3 SDRAM DIMM Options 1.1.6. QDR II and QDR II+ SRAM Clock Signals 1.1.7. QDR II and QDR II+ SRAM Command Signals 1.1.8. QDR II and QDR II+ SRAM Address Signals 1.1.9. QDR II and QDR II+ SRAM Data, BWS, and QVLD Signals 1.1.10. RLDRAM II and RLDRAM 3 Clock Signals 1.1.11. RLDRAM II and RLDRAM 3 Commands and Addresses 1.1.12. RLDRAM II and RLDRAM 3 Data, DM and QVLD Signals 1.1.13. LPDDR2 Clock Signal 1.1.14. LPDDR2 Command and Address Signal 1.1.15. LPDDR2 Data, Data Strobe, and DM Signals 1.1.16. Maximum Number of Interfaces 1.1.17. OCT Support
1.1.16. Maximum Number of Interfaces x
1.1.16.1. Maximum Number of DDR SDRAM Interfaces Supported per FPGA 1.1.16.2. Maximum Number of DDR2 SDRAM Interfaces Supported per FPGA 1.1.16.3. Maximum Number of DDR3 SDRAM Interfaces Supported per FPGA 1.1.16.4. Maximum Number of QDR II and QDR II+ SRAM Interfaces Supported per FPGA 1.1.16.5. Maximum Number of RLDRAM II Interfaces Supported per FPGA 1.1.16.6. Maximum Number of LPDDR2 SDRAM Interfaces Supported per FPGA
1.2. Guidelines for UniPHY-based External Memory Interface IP x
1.2.1. General Pin-out Guidelines for UniPHY-based External Memory Interface IP 1.2.2. Pin-out Rule Exceptions for ×36 Emulated QDR II and QDR II+ SRAM Interfaces in Arria II, Stratix III and Stratix IV Devices 1.2.3. Pin-out Rule Exceptions for RLDRAM II and RLDRAM 3 Interfaces 1.2.4. Pin-out Rule Exceptions for QDR II and QDR II+ SRAM Burst-length-of-two Interfaces 1.2.5. Pin Connection Guidelines Tables 1.2.6. PLLs and Clock Networks
1.2.2. Pin-out Rule Exceptions for ×36 Emulated QDR II and QDR II+ SRAM Interfaces in Arria II, Stratix III and Stratix IV Devices x
1.2.2.1. Timing Impact on x36 Emulation 1.2.2.2. Rules to Combine Groups 1.2.2.3. Determining the CQ/CQn Arrival Time Skew
1.2.3. Pin-out Rule Exceptions for RLDRAM II and RLDRAM 3 Interfaces x
1.2.3.1. Interfacing with ×9 RLDRAM II CIO Devices 1.2.3.2. Interfacing with ×18 RLDRAM II and RLDRAM 3 CIO Devices 1.2.3.3. Interfacing with RLDRAM II and RLDRAM 3 ×36 CIO Devices
1.2.5. Pin Connection Guidelines Tables x
1.2.5.1. DDR3 SDRAM With Leveling Interface Pin Utilization Applicable for Arria V GZ, Stratix III, Stratix IV, and Stratix V Devices 1.2.5.2. QDR II and QDR II+ SRAM Pin Utilization for Arria II, Arria V, Stratix III, Stratix IV, and Stratix V Devices 1.2.5.3. RLDRAM II CIO Pin Utilization for Arria II GZ, Arria V, Stratix III, Stratix IV, and Stratix V Devices  1.2.5.4. LPDDR2 Pin Utilization for Arria V, Cyclone V, and MAX 10 FPGA Devices 1.2.5.5. Additional Guidelines for Arria V GZ and Stratix V Devices 1.2.5.6. Additional Guidelines for Arria V ( Except Arria V GZ) Devices 1.2.5.7. Additional Guidelines for MAX 10 Devices 1.2.5.8. Additional Guidelines for Cyclone V Devices
1.2.6. PLLs and Clock Networks x
1.2.6.1. Number of PLLs Available in Intel® Device Families 1.2.6.2. Number of Enhanced PLL Clock Outputs and Dedicated Clock Outputs Available in Intel® Device Families 1.2.6.3. Number of Clock Networks Available in Intel® Device Families 1.2.6.4. Clock Network Usage in UniPHY-based Memory Interfaces—DDR2 and DDR3 SDRAM (1) (2) 1.2.6.5. Clock Network Usage in UniPHY-based Memory Interfaces—RLDRAM II, and QDR II and QDR II+ SRAM 1.2.6.6. PLL Usage for DDR, DDR2, and DDR3 SDRAM Without Leveling Interfaces 1.2.6.7. PLL Usage for DDR3 SDRAM With Leveling Interfaces
2. DDR2 and DDR3 SDRAM Board Design Guidelines x
2.1. Leveling and Dynamic Termination 2.2. DDR2 Terminations and Guidelines 2.3. DDR3 Terminations in Arria V, Cyclone V, Stratix III, Stratix IV, and Stratix V 2.4. Layout Approach 2.5. Channel Signal Integrity Measurement 2.6. Design Layout Guidelines 2.7. Package Deskew 2.8. Document Revision History
2.1. Leveling and Dynamic Termination x
2.1.1. Read and Write Leveling 2.1.2. Dynamic ODT 2.1.3. Dynamic On-Chip Termination 2.1.4. Dynamic On-Chip Termination in Stratix III and Stratix IV Devices 2.1.5. Dynamic OCT in Stratix V Devices
2.1.3. Dynamic On-Chip Termination x
2.1.3.1. FPGA Writing to Memory 2.1.3.2. FPGA Reading from Memory
2.2. DDR2 Terminations and Guidelines x
2.2.1. Termination for DDR2 SDRAM 2.2.2. DDR2 Design Layout Guidelines 2.2.3. General Layout Guidelines 2.2.4. Layout Guidelines for DDR2 SDRAM Interface
2.2.1. Termination for DDR2 SDRAM x
2.2.1.1. External Parallel Termination 2.2.1.2. On-Chip Termination 2.2.1.3. Recommended Termination Schemes
2.3. DDR3 Terminations in Arria V, Cyclone V, Stratix III, Stratix IV, and Stratix V x
2.3.1. Terminations for Single-Rank DDR3 SDRAM Unbuffered DIMM 2.3.2. Terminations for Multi-Rank DDR3 SDRAM Unbuffered DIMM 2.3.3. Terminations for DDR3 SDRAM Registered DIMM 2.3.4. Terminations for DDR3 SDRAM Load-Reduced DIMM 2.3.5. Terminations for DDR3 SDRAM Components With Leveling
2.3.5. Terminations for DDR3 SDRAM Components With Leveling x
2.3.5.1. DDR3 SDRAM Components With or Without Leveling
2.5. Channel Signal Integrity Measurement x
2.5.1. Importance of Accurate Channel Signal Integrity Information 2.5.2. Understanding Channel Signal Integrity Measurement 2.5.3. How to Enter Calculated Channel Signal Integrity Values 2.5.4. Guidelines for Calculating DDR3 Channel Signal Integrity
2.6. Design Layout Guidelines x
2.6.1. General Layout Guidelines 2.6.2. Layout Guidelines for DDR3 SDRAM Interfaces 2.6.3. Length Matching Rules 2.6.4. Spacing Guidelines 2.6.5. Layout Guidelines for DDR3 SDRAM Wide Interface (>72 bits)
2.6.5. Layout Guidelines for DDR3 SDRAM Wide Interface (>72 bits) x
2.6.5.1. Fly-By Network Design for Clock, Command, and Address Signals
2.7. Package Deskew x
2.7.1. Package Deskew Recommendation for Stratix V Devices 2.7.2. DQ/DQS/DM Deskew 2.7.3. Address and Command Deskew 2.7.4. Deskew Example 2.7.5. Package Migration 2.7.6. Package Deskew for RLDRAM II and RLDRAM 3
3. Dual-DIMM DDR2 and DDR3 SDRAM Board Design Guidelines x
3.1. General Layout Guidelines 3.2. Dual-Slot Unbuffered DDR2 SDRAM 3.3. Dual-Slot Unbuffered DDR3 SDRAM 3.4. Document Revision History
3.2. Dual-Slot Unbuffered DDR2 SDRAM x
3.2.1. Overview of ODT Control 3.2.2. DIMM Configuration 3.2.3. Dual-DIMM Memory Interface with Slot 1 Populated 3.2.4. Dual-DIMM with Slot 2 Populated 3.2.5. Dual-DIMM Memory Interface with Both Slot 1 and Slot 2 Populated 3.2.6. Dual-DIMM DDR2 Clock, Address, and Command Termination and Topology 3.2.7. Control Group Signals 3.2.8. Clock Group Signals
3.2.3. Dual-DIMM Memory Interface with Slot 1 Populated x
3.2.3.1. FPGA Writing to Memory 3.2.3.2. Write to Memory Using an ODT Setting of 150-ohm 3.2.3.3. Reading from Memory
3.2.4. Dual-DIMM with Slot 2 Populated x
3.2.4.1. FPGA Writing to Memory 3.2.4.2. Write to Memory Using an ODT Setting of 150-ohm 3.2.4.3. Reading from Memory
3.2.5. Dual-DIMM Memory Interface with Both Slot 1 and Slot 2 Populated x
3.2.5.1. FPGA Writing to Memory 3.2.5.2. Write to Memory in Slot 1 Using an ODT Setting of 75-ohm 3.2.5.3. Reading From Memory
3.3. Dual-Slot Unbuffered DDR3 SDRAM x
3.3.1. Comparison of DDR3 and DDR2 DQ and DQS ODT Features and Topology 3.3.2. Dual-DIMM DDR3 Clock, Address, and Command Termination and Topology 3.3.3. FPGA OCT Features
3.3.2. Dual-DIMM DDR3 Clock, Address, and Command Termination and Topology x
3.3.2.1. Address and Command Signals 3.3.2.2. Control Group Signals 3.3.2.3. Clock Group Signals
3.3.3. FPGA OCT Features x
3.3.3.1. Arria V, Cyclone V, Stratix III, Stratix IV, and Stratix V Devices 3.3.3.2. Arria II GX Devices
4. LPDDR2 SDRAM Board Design Guidelines x
4.1. LPDDR2 Guidance 4.2. Document Revision History
4.1. LPDDR2 Guidance x
4.1.1. LPDDR2 SDRAM Configurations 4.1.2. OCT Signal Terminations for Arria V and Cyclone V Devices 4.1.3. General Layout Guidelines 4.1.4. LPDDR2 Layout Guidelines
4.1.2. OCT Signal Terminations for Arria V and Cyclone V Devices x
4.1.2.1. Outputs from the FPGA to the LPDDR2 Component 4.1.2.2. Input to the FPGA from the LPDDR2 SDRAM Component 4.1.2.3. Termination Schemes
5. RLDRAM II and RLDRAM 3 Board Design Guidelines x
5.1. RLDRAM II Configurations 5.2. RLDRAM 3 Configurations 5.3. Signal Terminations 5.4. PCB Layout Guidelines 5.5. General Layout Guidelines 5.6. RLDRAM II and RLDRAM 3 Layout Guidelines 5.7. Layout Approach 5.8. Package Deskew for RLDRAM II and RLDRAM 3 5.9. Document Revision History
5.3. Signal Terminations x
5.3.1. Input to the FPGA from the RLDRAM Components 5.3.2. Outputs from the FPGA to the RLDRAM II and RLDRAM 3 Components 5.3.3. RLDRAM II Termination Schemes 5.3.4. RLDRAM 3 Termination Schemes
5.7. Layout Approach x
5.7.1. Arria V and Stratix V Board Setting Parameters
6. QDR II/II+ SRAM Board Design Guidelines x
6.1. QDR II SRAM Configurations 6.2. Signal Terminations 6.3. General Layout Guidelines 6.4. QDR II Layout Guidelines 6.5. QDR II SRAM Layout Approach 6.6. Package Deskew for QDR II 6.7. Document Revision History
6.2. Signal Terminations x
6.2.1. Output from the FPGA to the QDR II SRAM Component 6.2.2. Input to the FPGA from the QDR II SRAM Component 6.2.3. Termination Schemes
7. Implementing and Parameterizing Memory IP x
7.1. Design Flow 7.2. UniPHY-Based External Memory Interface IP 7.3. Document Revision History
7.1. Design Flow x
7.1.1. IP Catalog Design Flow 7.1.2. Platform Designer System Integration Tool Design Flow
7.1.1. IP Catalog Design Flow x
7.1.1.1. IP Catalog and Parameter Editor 7.1.1.2. Specifying Parameters for the IP Catalog Flow 7.1.1.3. Using Example Designs 7.1.1.4. Constraining the Design 7.1.1.5. Compiling the Design
7.1.1.4. Constraining the Design x
7.1.1.4.1. Adding Pins and DQ Group Assignments
7.1.2. Platform Designer System Integration Tool Design Flow x
7.1.2.1. Specify Parameters for the Platform Designer Flow 7.1.2.2. Completing the Platform Designer System
7.2. UniPHY-Based External Memory Interface IP x
7.2.1. Platform Designer Interfaces 7.2.2. Generated Files for Memory Controllers with the UniPHY IP 7.2.3. Parameterizing Memory Controllers 7.2.4. Board Settings 7.2.5. Controller Settings for UniPHY IP 7.2.6. Diagnostics for UniPHY IP
7.2.1. Platform Designer Interfaces x
7.2.1.1. DDR2 SDRAM Controller with UniPHY Intel FPGA IP Interfaces 7.2.1.2. DDR3 SDRAM Controller with UniPHY Intel FPGA IP Interfaces 7.2.1.3. LPDDR2 SDRAM Controller with UniPHY Intel FPGA IP Interfaces 7.2.1.4. QDR II and QDR II+ SRAM Controller with UniPHY Intel FPGA IP Interfaces 7.2.1.5. RLDRAM II Controller with UniPHY Intel FPGA IP Interfaces 7.2.1.6. RLDRAM 3 UniPHY Intel FPGA IP Interface
7.2.3. Parameterizing Memory Controllers x
7.2.3.1. PHY Settings for UniPHY IP 7.2.3.2. Memory Parameters for LPDDR2, DDR2 and DDR3 SDRAM Controller with UniPHY Intel FPGA IP 7.2.3.3. Memory Parameters for QDR II and QDR II+ SRAM Controller with UniPHY Intel FPGA IP 7.2.3.4. Memory Parameters for RLDRAM II Controller with UniPHY Intel FPGA IP 7.2.3.5. Memory Timing Parameters for DDR2, DDR3, and LPDDR2 SDRAM Controller with UniPHY Intel FPGA IP 7.2.3.6. Memory Timing Parameters for QDR II and QDR II+ SRAM Controller with UniPHY Intel FPGA IP 7.2.3.7. Memory Timing Parameters for RLDRAM II Controller with UniPHY Intel FPGA IP 7.2.3.8. Memory Parameters for RLDRAM 3 UniPHY Intel FPGA IP
7.2.3.2. Memory Parameters for LPDDR2, DDR2 and DDR3 SDRAM Controller with UniPHY Intel FPGA IP x
7.2.3.2.1. Memory Initialization Options for DDR2 7.2.3.2.2. Memory Initialization Options for DDR3 7.2.3.2.3. Memory Initialization Options for LPDDR2
7.2.4. Board Settings x
7.2.4.1. Setup and Hold Derating for UniPHY IP 7.2.4.2. Intersymbol Interference Channel Signal Integrity for UniPHY IP 7.2.4.3. Board Skews for UniPHY IP
7.2.4.3. Board Skews for UniPHY IP x
7.2.4.3.1. Board Skew Parameters for LPDDR2/DDR2/DDR3 SDRAM 7.2.4.3.2. Board Skew Parameters for QDR II and QDR II+ 7.2.4.3.3. Board Skew parameters for RLDRAM II and RLDRAM 3
8. Simulating Memory IP x
8.1. Simulation Options 8.2. Simulation Walkthrough with UniPHY IP 8.3. Document Revision History
8.2. Simulation Walkthrough with UniPHY IP x
8.2.1. Simulation Scripts 8.2.2. Preparing the Vendor Memory Model 8.2.3. Functional Simulation with Verilog HDL 8.2.4. Functional Simulation with VHDL 8.2.5. Simulating the Example Design 8.2.6. UniPHY Abstract PHY Simulation 8.2.7. PHY-Only Simulation 8.2.8. Post-fit Functional Simulation 8.2.9. Simulation Issues
8.2.8. Post-fit Functional Simulation x
8.2.8.1. Running Post-fit Simulation
9. Analyzing Timing of Memory IP x
9.1. Memory Interface Timing Components 9.2. FPGA Timing Paths 9.3. Timing Constraint and Report Files for UniPHY IP 9.4. Timing Analysis Description 9.5. Timing Report DDR 9.6. Report SDC 9.7. Calibration Effect in Timing Analysis 9.8. Timing Model Assumptions and Design Rules 9.9. Common Timing Closure Issues 9.10. Optimizing Timing 9.11. Timing Deration Methodology for Multiple Chip Select DDR2 and DDR3 SDRAM Designs 9.12. Performing I/O Timing Analysis 9.13. Document Revision History
9.1. Memory Interface Timing Components x
9.1.1. Source-Synchronous Paths 9.1.2. Calibrated Paths 9.1.3. Internal FPGA Timing Paths 9.1.4. Other FPGA Timing Parameters
9.2. FPGA Timing Paths x
9.2.1. Arria II Device PHY Timing Paths 9.2.2. Stratix III and Stratix IV PHY Timing Paths 9.2.3. Arria V, Arria V GZ, Cyclone V, and Stratix V Timing paths
9.4. Timing Analysis Description x
9.4.1. UniPHY IP Timing Analysis
9.4.1. UniPHY IP Timing Analysis x
9.4.1.1. Address and Command 9.4.1.2. PHY or Core 9.4.1.3. PHY or Core Reset 9.4.1.4. Read Capture and Write 9.4.1.5. Read Resynchronization 9.4.1.6. DQS versus CK—Arria II GX and Cyclone IV Devices 9.4.1.7. Write Leveling tDQSS 9.4.1.8. Write Leveling tDSH/tDSS 9.4.1.9. DK versus CK (RLDRAM II with UniPHY) 9.4.1.10. Bus Turnaround Time
9.4.1.4. Read Capture and Write x
9.4.1.4.1. Stratix III 9.4.1.4.2. Arria II, Arria V, Cyclone V, Stratix IV and Stratix V
9.7. Calibration Effect in Timing Analysis x
9.7.1. Calibration Emulation for Calibrated Path 9.7.2. Calibration Error or Quantization Error 9.7.3. Calibration Uncertainties 9.7.4. Memory Calibration
9.8. Timing Model Assumptions and Design Rules x
9.8.1. Memory Clock Output Assumptions 9.8.2. Write Data Assumptions 9.8.3. Read Data Assumptions 9.8.4. DLL Assumptions 9.8.5. PLL and Clock Network Assumptions for Stratix III Devices
9.8.1. Memory Clock Output Assumptions x
9.8.1.1. Memory Clock Assumptions for Stratix III Devices
9.8.2. Write Data Assumptions x
9.8.2.1. Write Data Assumptions for Stratix III Devices
9.8.3. Read Data Assumptions x
9.8.3.1. Read Data Assumptions for Stratix III Devices
9.9. Common Timing Closure Issues x
9.9.1. Missing Timing Margin Report 9.9.2. Incomplete Timing Margin Report 9.9.3. Read Capture Timing 9.9.4. Write Timing 9.9.5. Address and Command Timing 9.9.6. PHY Reset Recovery and Removal 9.9.7. Clock-to-Strobe (for DDR and DDR2 SDRAM Only) 9.9.8. Read Resynchronization and Write Leveling Timing (for SDRAM Only)
9.11. Timing Deration Methodology for Multiple Chip Select DDR2 and DDR3 SDRAM Designs x
9.11.1. Multiple Chip Select Configuration Effects 9.11.2. Timing Deration using the Board Settings
9.11.1. Multiple Chip Select Configuration Effects x
9.11.1.1. ISI Effects 9.11.1.2. Calibration Effects 9.11.1.3. Board Effects
9.11.2. Timing Deration using the Board Settings x
9.11.2.1. Slew Rates 9.11.2.2. Slew Rate Setup, Hold, and Derating Calculation 9.11.2.3. Intersymbol Interference 9.11.2.4. Measuring Eye Reduction for Address/Command, DQ, and DQS Setup and Hold Time
9.12. Performing I/O Timing Analysis x
9.12.1. Performing I/O Timing Analysis with Third-Party Simulation Tools 9.12.2. Performing Advanced I/O Timing Analysis with Board Trace Delay Model
10. Debugging Memory IP x
10.1. Resource and Planning Issues 10.2. Interface Configuration Performance Issues 10.3. Functional Issue Evaluation 10.4. Timing Issue Characteristics 10.5. Verifying Memory IP Using the Signal Tap II Logic Analyzer 10.6. Hardware Debugging Guidelines 10.7. Categorizing Hardware Issues 10.8. EMIF Debug Toolkit Overview 10.9. Document Revision History
10.1. Resource and Planning Issues x
10.1.1. Dedicated DLL Resources 10.1.2. Dedicated IOE DQS Group Resources and Pins 10.1.3. Specific PLL Resources 10.1.4. Specific Global, Regional and Dual-Regional Clock Net Resources 10.1.5. Planning Your Design 10.1.6. Optimizing Design Utilization
10.2. Interface Configuration Performance Issues x
10.2.1. Interface Configuration Bottleneck and Efficiency Issues
10.3. Functional Issue Evaluation x
10.3.1. Correct Combination of the Quartus Prime Software and ModelSim* - Intel® FPGA Edition Device Models 10.3.2. Intel® IP Memory Model 10.3.3. Vendor Memory Model 10.3.4. Insufficient Memory in Your PC 10.3.5. Transcript Window Messages 10.3.6. Passing Simulation 10.3.7. Modifying the Example Driver to Replicate the Failure
10.4. Timing Issue Characteristics x
10.4.1. Evaluating FPGA Timing Issues 10.4.2. Evaluating External Memory Interface Timing Issues
10.5. Verifying Memory IP Using the Signal Tap II Logic Analyzer x
10.5.1. Signals to Monitor with the Signal Tap II Logic Analyzer
10.6. Hardware Debugging Guidelines x
10.6.1. Create a Simplified Design that Demonstrates the Same Issue 10.6.2. Measure Power Distribution Network 10.6.3. Measure Signal Integrity and Setup and Hold Margin 10.6.4. Vary Voltage 10.6.5. Use Freezer Spray and Heat Gun 10.6.6. Operate at a Lower Speed 10.6.7. Determine Whether the Issue Exists in Previous Versions of Software 10.6.8. Determine Whether the Issue Exists in the Current Version of Software 10.6.9. Try A Different PCB 10.6.10. Try Other Configurations 10.6.11. Debugging Checklist
10.7. Categorizing Hardware Issues x
10.7.1. Signal Integrity Issues 10.7.2. Hardware and Calibration Issues
10.7.1. Signal Integrity Issues x
10.7.1.1. Characteristics of Signal Integrity Issues 10.7.1.2. Evaluating SignaI Integrity Issues
10.7.1.2. Evaluating SignaI Integrity Issues x
10.7.1.2.1. Skew 10.7.1.2.2. Crosstalk 10.7.1.2.3. Power System 10.7.1.2.4. Clock Signals 10.7.1.2.5. Read Data Valid Window and Eye Diagram 10.7.1.2.6. Write Data Valid Window and Eye Diagram 10.7.1.2.7. OCT and ODT Usage
10.7.2. Hardware and Calibration Issues x
10.7.2.1. Evaluating Hardware and Calibration Issues
10.7.2.1. Evaluating Hardware and Calibration Issues x
10.7.2.1.1. Write Timing Margin 10.7.2.1.2. Read Timing Margin 10.7.2.1.3. Address and Command Timing Margin 10.7.2.1.4. Resynchronization Timing Margin 10.7.2.1.5. Postamble Timing Issues and Margin 10.7.2.1.6. Intermittent Issue Evaluation
11. Optimizing the Controller x
11.1. Factors Affecting Efficiency 11.2. Ways to Improve Efficiency 11.3. Document Revision History
11.1. Factors Affecting Efficiency x
11.1.1. Interface Standard 11.1.2. Bank Management Efficiency 11.1.3. Data Transfer
11.2. Ways to Improve Efficiency x
11.2.1. DDR2 SDRAM Controller 11.2.2. Auto-Precharge Commands 11.2.3. Additive Latency 11.2.4. Bank Interleaving 11.2.5. Command Queue Look-Ahead Depth 11.2.6. Additive Latency and Bank Interleaving 11.2.7. User-Controlled Refresh 11.2.8. Frequency of Operation 11.2.9. Burst Length 11.2.10. Series of Reads or Writes 11.2.11. Data Reordering 11.2.12. Starvation Control 11.2.13. Command Reordering 11.2.14. Bandwidth 11.2.15. Efficiency Monitor
12. PHY Considerations x
12.1. Core Logic and User Interface Data Rate 12.2. Hard and Soft Memory PHY 12.3. Sequencer 12.4. PLL, DLL and OCT Resource Sharing 12.5. Pin Placement Consideration 12.6. Document Revision History
13. Power Estimation Methods for External Memory Interfaces x
13.1. Performing Vector-Based Power Analysis with the Power Analyzer 13.2. Document Revision History
1. Planning Pin and FPGA Resources
2. DDR2 and DDR3 SDRAM Board Design Guidelines
3. Dual-DIMM DDR2 and DDR3 SDRAM Board Design Guidelines
4. LPDDR2 SDRAM Board Design Guidelines
5. RLDRAM II and RLDRAM 3 Board Design Guidelines
6. QDR II/II+ SRAM Board Design Guidelines
7. Implementing and Parameterizing Memory IP
8. Simulating Memory IP
9. Analyzing Timing of Memory IP
10. Debugging Memory IP
11. Optimizing the Controller
12. PHY Considerations
13. Power Estimation Methods for External Memory Interfaces

2.2.4. Layout Guidelines for DDR2 SDRAM Interface

Unless otherwise specified, the following guidelines apply to the following topologies:
  • DIMM—UDIMM topology
  • DIMM—RDIMM topology
  • Discrete components laid out in UDIMM topology
  • Discrete components laid out in RDIMM topology

Trace lengths for CLK and DQS should tightly match for each memory component. To match the trace lengths on the board, a balanced tree topology is recommended for clock and address and command signal routing. In addition to matching the trace lengths, you should ensure that DDR timing is passing in the Report DDR Timing report. For Stratix devices, this timing is shown as Write Leveling tDQSS timing. For Arria and Cyclone devices, this timing is shown as CK vs DQS timing

For a table of device family topology support, refer to Leveling and Dynamic ODT.

The following table lists DDR2 SDRAM layout guidelines. These guidelines are Intel recommendations, and should not be considered as hard requirements. You should perform signal integrity simulation on all the traces to verify the signal integrity of the interface. You should extract the slew rate and propagation delay information, enter it into the IP and compile the design to ensure that timing requirements are met.

Note: The following layout guidelines also apply to DDR3 SDRAM without leveling interfaces.
Table 28.  DDR2 SDRAM Layout Guidelines   (1)

Parameter

Guidelines

DIMMs

If you consider a normal DDR2 unbuffered, unregistered DIMM, essentially you are planning to perform the DIMM routing directly on your PCB. Therefore, each address and control pin routes from the FPGA (single pin) to all memory devices must be on the same side of the FPGA.

General Routing

  • All data, address, and command signals must have matched length traces ± 50 ps.
  • All signals within a given Byte Lane Group should be matched length with maximum deviation of ±10 ps and routed in the same layer.

Clock Routing

  • A 4.7 K-ohm resistor to ground is recommended for each Clock Enable signal. You can place the resistor at either the memory end or the FPGA end of the trace.
  • Route clocks on inner layers with outer-layer run lengths held to under 500 mils (12.7 mm)
  • These signals should maintain a10-mil (0.254 mm) spacing from other nets
  • Clocks should maintain a length-matching between clock pairs of ±5 ps.
  • Differential clocks should maintain a length-matching between P and N signals of ±2 ps, routed in parallel.
  • Space between different pairs should be at least three times the space between the differential pairs and must be routed differentially (5-mil trace, 10‑15 mil space on centers), and equal to the signals in the Address/Command Group or up to 100 mils (2.54 mm) longer than the signals in the Address/Command Group.
  • Trace lengths for CLK and DQS should closely match for each memory component. To match trace lengths on the board, a balanced tree topology is recommended for clock and address and command signal routing. For Stratix device families, ensure that Write Leveling tDQSS is passing in the DDR timing report; for Arria and Cyclone device families, verify that CK vs DQS timing is passing in the DDR timing report.

Address and Command Routing

  • Unbuffered address and command lines are more susceptible to cross-talk and are generally noisier than buffered address or command lines. Therefore, un‑buffered address and command signals should be routed on a different layer than data signals (DQ) and data mask signals (DM) and with greater spacing.
  • Do not route differential clock (CK) and clock enable (CKE) signals close to address signals.

DQ, DM, and DQS Routing Rules

  • Keep the distance from the pin on the DDR2 DIMM or component to the termination resistor pack (VTT) to less than 500 mils for DQS[x] Data Groups.
  • Keep the distance from the pin on the DDR2 DIMM or component to the termination resistor pack (VTT) to less than 1000 mils for the ADR_CMD_CTL Address Group.
  • Parallelism rules for the DQS[x] Data Groups are as follows:
    • 4 mils for parallel runs < 0.1 inch (approximately 1× spacing relative to plane distance)
    • 5 mils for parallel runs < 0.5 inch (approximately 1× spacing relative to plane distance)
    • 10 mils for parallel runs between 0.5 and 1.0 inches (approximately 2× spacing relative to plane distance)
    • 15 mils for parallel runs between 1.0 and 6.0 inch (approximately 3× spacing relative to plane distance)
  • Parallelism rules for the ADR_CMD_CTL group and CLOCKS group are as follows:
    • 4 mils for parallel runs < 0.1 inch (approximately 1× spacing relative to plane distance)
    • 10 mils for parallel runs < 0.5 inch (approximately 2× spacing relative to plane distance)
    • 15 mils for parallel runs between 0.5 and 1.0 inches (approximately 3× spacing relative to plane distance)
    • 20 mils for parallel runs between 1.0 and 6.0 inches (approximately 4× spacing relative to plane distance)
  • All signals are to maintain a 20-mil separation from other, non‑related nets.
  • All signals must have a total length of < 6 inches.
  • Trace lengths for CLK and DQS should closely match for each memory component. To match trace lengths on the board, a balanced tree topology is recommended for clock and address and command signal routing. For Stratix device families, ensure that Write Leveling tDQSS is passing in the DDR timing report; for Arria and Cyclone device families, verify that CK vs DQS timing is passing in the DDR timing report.

Termination Rules

  • When pull-up resistors are used, fly-by termination configuration is recommended. Fly-by helps reduce stub reflection issues.
  • Pull-ups should be within 0.5 to no more than 1 inch.
  • Pull up is typically 56-ohms.
  • If using resistor networks:
  • Do not share R-pack series resistors between address/command and data lines (DQ, DQS, and DM) to eliminate crosstalk within pack.
  • Series and pull up tolerances are 1–2%.
  • Series resistors are typically 10 to 20-ohm.
  • Address and control series resistor typically at the FPGA end of the link.
  • DM, DQS, DQ series resistor typically at the memory end of the link (or just before the first DIMM).
  • If termination resistor packs are used:
  • The distance to your memory device should be less than 750 mils.
  • The distance from your FPGA device should be less than 1250 mils.

Quartus Prime Software Settings for Board Layout

  • To perform timing analyses on board and I/O buffers, use third party simulation tool to simulate all timing information such as skew, ISI, crosstalk, and type the simulation result into the UniPHY board setting panel.
  • Do not use advanced I/O timing model (AIOT) or board trace model unless you do not have access to any third party tool. AIOT provides reasonable accuracy but tools like HyperLynx provides better result. In operations with higher frequency, it is crucial to properly simulate all signal integrity related uncertainties.
  • The Quartus Prime software does timing check to find how fast the controller issues a write command after a read command, which limits the maximum length of the DQ/DQS trace. Check the turnaround timing in the Report DDR timing report and ensure the margin is positive before board fabrication. Functional failure happens if the margin is less than 0.

Note to Table:

  1. For point-to-point and DIMM interface designs, refer to the Micron website, www.micron.com.
Figure 18. Balanced Tree Topology


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