Device-Specific Power Delivery Network (PDN) Tool 2.0 User Guide

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ID 683293
Date 8/24/2021
Public
Document Table of Contents
Document Table of Contents x
1. Device-Specific Power Delivery Network (PDN) Tool 2.0 User Guide
1. Device-Specific Power Delivery Network (PDN) Tool 2.0 User Guide x
1.1. Overview 1.2. PDN Decoupling Methodology Review 1.3. PDN Tool Setup and Result Optimization 1.4. Device-Specific PDN Tool 2.0 Known Issues and Their Solutions 1.5. Document Revision History for the Device-Specific Power Delivery Network (PDN) Tool 2.0 User Guide
1.2. PDN Decoupling Methodology Review x
1.2.1. PDN Circuit Topology 1.2.2. Major Tabs of the PDN Tool 2.0 1.2.3. Design PCB Decoupling Using the PDN Tool 2.0 1.2.4. Troubleshooting ZEFF
1.2.1. PDN Circuit Topology x
1.2.1.1. ZTARGET 1.2.1.2. FEFFECTIVE
1.2.2. Major Tabs of the PDN Tool 2.0 x
1.2.2.1. System_Decap 1.2.2.2. Stackup 1.2.2.3. BGA_Via 1.2.2.4. Plane_Cap 1.2.2.5. Cap_Mount 1.2.2.6. X2Y_Mount 1.2.2.7. Library 1.2.2.8. Enlarged_Graph
1.2.2.1. System_Decap x
1.2.2.1.1. Device Selection Section 1.2.2.1.2. Power Rail Data and Configuration Section 1.2.2.1.3. Meeting Target Impedance when Entering 0 A into the PDN Tool 1.2.2.1.4. Dealing with Multiple Shared Power Supply Pin Types 1.2.2.1.5. VRM Data Section 1.2.2.1.6. Rail Group Summary Section 1.2.2.1.7. VRM Impedance Section 1.2.2.1.8. BGA Via Section 1.2.2.1.9. Plane Section 1.2.2.1.10. Spreading Section 1.2.2.1.11. Implementing Split Planes 1.2.2.1.12. FEFFECTIVE Section 1.2.2.1.13. Decoupling Section 1.2.2.1.14. Results Summary Section 1.2.2.1.15. Recommended Flow for Deriving Decoupling for an FPGA System using the System_Decap Tab
1.2.2.2. Stackup x
1.2.2.2.1. Stackup Data 1.2.2.2.2. Full Stackup
1.2.2.7. Library x
1.2.2.7.1. Two-Terminal Decoupling Capacitors 1.2.2.7.2. Bulk Capacitors 1.2.2.7.3. X2Y Decoupling Capacitors 1.2.2.7.4. BGA Via and Plane Capacitance 1.2.2.7.5. VRM Library 1.2.2.7.6. Spreading R and L Parasitics 1.2.2.7.7. Dielectric Material Library 1.2.2.7.8. User Set FEFFECTIVE
1.2.3. Design PCB Decoupling Using the PDN Tool 2.0 x
1.2.3.1. Pre-Layout Instructions 1.2.3.2. Deriving Decoupling in a Single-Rail Scenario 1.2.3.3. Deriving Decoupling in the Power-Sharing Scenarios
1.2.4. Troubleshooting ZEFF x
1.2.4.1. Strategies for Correcting a High ZEFF
1.3. PDN Tool Setup and Result Optimization x
1.3.1. Setting Up a PCB Stackup 1.3.2. Setting up a Power Group 1.3.3. Optimizing in Pre-Layout 1.3.4. Further Optimizing for Better Accuracy 1.3.5. Correlation
1.3.1. Setting Up a PCB Stackup x
1.3.1.1. Selecting Your Device 1.3.1.2. Inputting Stackup Data
1.3.1.2. Inputting Stackup Data x
1.3.1.2.1. Using a Custom Dielectric Material
1.3.2. Setting up a Power Group x
1.3.2.1. Selecting the Rails 1.3.2.2. Rail Group Summary 1.3.2.3. VRM Impedance 1.3.2.4. BGA Via 1.3.2.5. Calculating Plane 1.3.2.6. Plane Spreading Parasitics 1.3.2.7. FEFFECTIVE and Decoupling Result Summary
1.3.3. Optimizing in Pre-Layout x
1.3.3.1. Checking the Capacitor Model 1.3.3.2. Optimizing the Decap Count
1. Device-Specific Power Delivery Network (PDN) Tool 2.0 User Guide

1.3.2.3. VRM Impedance

The PDN tool has default Library R and L models for VRM Impedance.

If a VRM model is available from the vendor, you can select the Custom option to replace the default values by directly overriding the new values.

Figure 27. VRM Impedance
Note: The single R and L assumption in the tool is for 1-phase single VRM. For multi-phase VRM usage, the simplest method for rough estimation is to divide the default numbers by the number of phases. For example, if the default values for a single switcher and four-phase VRM are R = 1 mΩ and L = 20 nH, then you can estimate the final values as R = 0.25 mΩ and L = 5 nH. Make note of how many phases of VRM you use in each PDN design. The tool may recommend bulk cap solutions that are significantly different.
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