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Intel 820E 2.7.2.7. Via Compensation , 2.7.2.8. Length Matching and Via Compensation Example

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Intel® 820E Chipset

R

52 Design Guide

It is necessary to compensate for the slight difference in electrical characteristics between a dummy via

and a real via. Refer to the following section for more information on via compensation.

2.7.2.7. Via Compensation

As described in Section 2.7.2.1, all signals must have the same number of vias. As a result, each trace

will have one via (near the BGA pad) because some RSL signals must be routed on the bottom of the

motherboard. Therefore, it is necessary to place a dummy via on all signals that are routed on the top

layer. Because the electrical characteristics of a dummy via do not exactly match the electrical

characteristics of a real via, additional compensation must be performed for each signal that has a dummy

via. Each signal with a dummy via must have 25 mils of additional trace length. That is:

Real via = Dummy via + 25 mils of trace length

This 25 mils of additional trace length must be added to each signal routed on the top layer after length

matching, as documented in Section 2.7.2.6.

Figure 31. “Dummy” Via vs. “Real” Via

“DUMMY Via”

PCB PCB

“REAL Via”

PCB PCB

Trace Trace

Via Via

Trace

dum_vias_vs_real.v

2.7.2.8. Length Matching and Via Compensation Example

Table 8 can be used to ensure that the RSL signals are the correct length.

Note: 2000 mils was chosen as an example nominal RSL length.

Contents

Main Intel 820E Chipset Intel 820E Chipset 2 Design Guide Contents Page Page Page Page Figures Page Tables Page Revision History 1. Introduction 1.1. About This Design Guide 1.2. Reference Documents 1.3. System Overview 1.3.1. Chipset Components Memory Controller Hub (MCH) I/O Controller Hub 2 (ICH2) FWH Flash BIOS ISA Bridge 1.3.2. Bandwidth Summary 1.3.3. System Configuration Page 1.4. Platform Initiatives 1.4.1. Direct Rambus RAM (RDRAM*) 1.4.2. Streaming SIMD Extensions 1.4.3. AGP 2.0. 1.4.4. Hub Interface 1.4.5. Integrated LAN Controller 1.4.6. Ultra ATA/100 Support 1.4.7. Expanded USB Support 1.4.8. Manageability TCO Timer Page 1.4.9. AC97 Intel 820E Chipset 24 Design Guide Figure 4. (A-C) AC97 Connections 1.4.10. Low-Pin-Count (LPC) Interface Page 2. Layout/Routing Guidelines 2.1. General Recommendations 2.2. Component Quadrant Layout Page 2.3. Intel 820E Chipset Component Placement 2.4. Core Chipset Routing Recommendations Page 2.5. Source-Synchronous Strobing 2.6. Differential Clocking/Strobing 2.7. Direct RDRAM* Interface 2.7.1. Stack-Up 2.7.2. Direct RDRAM* Layout Guidelines 2.7.2.1. RSL Routing Page Page 2.7.2.2. RSL Termination 2.7.2.3. Direct RDRAM* Ground Plane Reference 3.3-V Plane 1.8-V Plane Wrong MCH RIMM2 Required 3.3-V Plane 2.7.2.4. Direct RDRAM* Connector Compensation Page Page Page Page Page 2.7.2.4.1. Direct RDRAM* Channel Connector Compensation Enhancement Recommendation Page 2.7.2.5. RSL Signal Layer Alternation MCH 2.7.2.6. Length Matching Methods Page 2.7.2.7. Via Compensation 2.7.2.8. Length Matching and Via Compensation Example Intel 820E Chipset Design Guide 53 Table 8. Line Matching and Via Compensation Example1,2,3,4,5,6,7,8,9,10 2.7.3. Direct RDRAM* Reference Voltage 2.7.4. High-Speed CMOS Routing 2.7.4.1. SIO Routing 2.7.4.2. Suspend-to-RAM Shunt Transistor 2.7.5. Direct RDRAM* Clock Routing 2.7.6. Direct RDRAM* Design Checklist Page Page 2.8. AGP 2.0 2.8.1. AGP Interface Signal Groups Signal Groups 2.8.2. 1 Timing Domain Routing Guidelines 2.8.3. 2/4 Timing Domain Routing Guidelines Interfaces < 6 Inches Interfaces > 6 Inches and < 7.25 Inches All AGP Interfaces 2.8.4. AGP 2.0 Routing Summary 2.8.5. AGP Clock Routing 2.8.6. General AGP Routing Guidelines 2.8.6.1. Recommendations Decoupling Ground Reference 2.8.7. VDDQ Generation and TYPEDET# Page 2.8.8. VREF Generation for AGP 2.0 (2 and 4) Intel 820E Chipset GMCH Design Guide 69 1.5-V AGP Card 2.8.9. Compensation 2.8.10. AGP Pull-Ups 2.8.10.1. AGP Signal Voltage Tolerance List 2.8.11. Motherboard / Add-in Card Interoperability 2.8.12. AGP Universal Retention Mechanism (RM) Page 2.9. Hub Interface 2.9.1. 8-Bit Hub Interface Routing Guidelines 2.9.1.1. 8-Bit Hub Interface Data Signals 2.9.1.2. 8-Bit Hub Interface Strobe Signals 2.9.1.3. 8-Bit Hub Interface HUBREF Generation/Distribution Page 2.9.1.4. 8-Bit Hub Interface Compensation 2.9.1.5. 8-Bit Hub Interface Decoupling Guidelines 2.10. System Bus Design Pentium III Processor for the Intel PGA370 Socket Layout Guidelines 2.10.1. System Bus Ground Plane Reference GND Plane 2.11. Additional Host Bus Guidelines Minimizing Crosstalk on the AGTL+ Interface Additional Considerations 2.12. IDE Interface Cable 2.12.1. Cable Detection for Ultra ATA/66 and Ultra ATA/100 2.12.2. Combination Host-Side/Device-Side Cable Detection Page 2.12.3. Device-Side Cable Detection Intel 820E Chipset Design Guide 83 2.12.4. Primary IDE Connector Requirements Figure 48. Connection Requirements for Primary IDE Connector NOTES: Intel 820E Chipset 2.12.5. Secondary IDE Connector Requirements Figure 49. Connection Requirements for Secondary IDE Connector NOTES: 2.13. AC97 2.13.1. AC97 Audio Codec Detect Circuit and Configuration Options CNR BoardMotherboard CNR Connector Intel 820E Chipset 88 Design Guide CNR BoardMotherboard CNR Connector CNR Connector CNR BoardMotherboard Page 2.13.2. Communication and Networking Riser (CNR) 2.13.3. AC97 Routing 2.13.4. Motherboard Implementation 2.14. USB 2.14.1. Using Native USB Interface 2.14.3. Disabling the Native USB Interface of ICH2 2.15. ISA Support 2.16. I/O APIC Design Recommendation 2.17. SMBus/SMLink Interface Page 2.18. PCI ICH2 2.19. RTC 2.19.1. RTC Crystal 2.19.2. External Capacitors 2.19.3. RTC Layout Considerations 2.19.4. RTC External Battery Connection 2.19.5. RTC External RTCRST Circuit 2.19.6. RTC Routing Guidelines 2.19.7. VBIAS DC Voltage and Noise Measurements 2.19.8. RTC-Well Input Strap Requirements 2.20. SPKR Pin Consideration 2.21. ICH2 PIRQ Routing ICH2 2.22. LAN Layout Guidelines 2.22.1. ICH2 LAN Interconnect Guidelines 2.22.1.1. Bus Topologies 2.22.1.2. Point-to-Point Interconnect 2.22.1.3. LOM/CNR Interconnect ICH2 Res. pack CNR PLC card B APLC C D 2.22.1.4. Signal Routing and Layout Page 2.22.2. General LAN Routing Guidelines and Considerations 2.22.2.1. General Trace Routing Considerations 2.22.2.1.1. Trace Geometry and Length 2.22.2.1.2. Signal Isolation 2.22.2.2. Power and Ground Connections 2.22.2.2.1. General Power and Ground Plane Considerations Page 2.22.2.3. 4-Layer Board Design Top-Layer Routing Ground Plane Power Plane Bottom Layer Routing Page 2.22.3. Intel 82562EH Home/PNA* Guidelines 2.22.3.1. Power and Ground Connections 2.22.3.2. Guidelines for Intel 82562EH Component Placement 2.22.3.3. Crystals and Oscillators 2.22.3.4. Phoneline HPNA Termination Page 2.22.3.5.3. Distance from LPF to Phone RJ11 2.22.4. Intel 82562ET / Intel 82562EM Component Guidelines 2.22.4.1. Guidelines for Intel 82562ET / Intel 82562EM Component Placement 2.22.4.2. Crystals and Oscillators 2.22.4.3. Intel 82562ET / Intel 82562EM Component Termination Resistors 2.22.4.4. Critical Dimensions 2.22.4.4.1. Distance from Magnetics Module to RJ45 2.22.4.4.2. Distance from the Intel 82562ET Component to the Magnetics Module 2.22.4.5. Reducing Circuit Inductance 2.22.4.6. Terminating Unused Connections 2.22.4.6.1. Termination Plane Capacitance Intel 820E Chipset 2.22.5. Intel 82562ET/EM Disable Guidelines LAN Disable Circuit Figure 75. Intel 82562ET/EM Disable Circuit MMBT3906 2.22.6. Intel 82562ET and Intel 82562EH Components Dual- Footprint Guidelines Page 2.22.7. ICH2 Decoupling Recommendations Page 2.23. FWH Flash BIOS Guidelines 2.23.1. In-Circuit FWH Flash BIOS Programming 2.23.2. FWH Flash BIOS VPP Design Guidelines Intel 820E Chipset 2.24. ICH2 Design Checklist Table 26. PCI Interface Checklist Items Recommendations Reason/Effect Intel 820E Chipset 126 Design Guide Table 27. Hub Interface Table 28. LAN Interface Intel 820E Chipset Design Guide 127 Table 31. Interrupt Interface Checklist Items Recommendations Reason/Effect Intel 820E Chipset 128 Design Guide Table 32. GPIO Table 33. USB Interface Intel 820E Chipset Design Guide 129 Table 34. Power Management Table 35. Processor Signals Page Intel 820E Chipset Design Guide 131 Table 39. Miscellaneous Signals Table 40. Power Intel 820E Chipset 132 Design Guide Figure 73. 5VREF Circuitry Vcc supply (3.3 V) 5 V supply Page Intel 820E Chipset 134 Design Guide 2.25. ICH2 Layout Checklist Table 43. 8-Bit Hub Interface Table 44. IDE Interface Table 45. USB Intel 820E Chipset Design Guide 135 Table 46. LAN Connect I/F Intel 820E Chipset 136 Design Guide # Layout Recommendations Yes No Comments Table 47. AC97 Intel 820E Chipset Design Guide 137 Table 49. CK-SKS Clocking # Layout Recommendations Yes No Comments Page 3. Advanced System Bus Design 3.1. Terminology and Definitions Page 3.2. AGTL+ Design Guidelines Guideline Methodology 3.2.1. Initial Timing Analysis Page Intel 820E Chipset 144 Design Guide The following two tables were derived assuming the following: CLKSKEW = 0.2 ns 3.2.2. Determine the Desired General Topology, Layout, and Routing 3.2.3. Pre-Layout Simulation 3.2.3.1. Methodology 3.2.3.2. Sensitivity Analysis 3.2.3.3. Monte Carlo Analysis 3.2.3.4. Simulation Criteria 3.2.4. Place and Route Board 3.2.4.1. Estimate Component-to-Component Spacing for AGTL+ Signals 3.2.4.2. Layout and Route Board 3.2.4.3. Host Clock Routing 3.2.4.4. APIC Data Bus Routing ICH2 Intel PGA370 3.2.5. Post-Layout Simulation 3.2.5.2. Crosstalk Analysis 3.2.5.3. Monte Carlo Analysis 3.2.6. Validation 3.2.6.1. Measurements 3.2.6.2. Flight Time Simulation 3.2.6.3. Flight Time Hardware Validation 3.3. Theory 3.3.1. AGTL+ 3.3.2. Timing Requirements 3.3.3. Crosstalk Theory 3.3.3.1. Potential Termination Crosstalk Problems 3.4. More Details and Insight 3.4.1. Textbook Timing Equations 3.4.2. Effective Impedance and Tolerance/Variation 3.4.3. Power/Reference Planes, PCB Stack-Up, and High-Frequency Decoupling 3.4.3.1. Power Distribution 3.4.3.2. Reference Planes and PCB Stack-Up Page 3.4.3.3. High-Frequency Decoupling 3.4.4. Clock Routing 3.5. Definitions of Flight Time Measurements/Corrections and Signal Quality 3.5.1. VREF Guard Band 3.5.2. Ringback Levels 3.5.3. Overdrive Region 3.5.4. Flight Time Definition and Measurement 3.6. Conclusion 4. Clocking 4.1. Clock Generation Intel 820E Chipset 164 Design Guide Figure 86. Intel 820E Chipset Platform Clock Distribution Intel 820E Chipset Design Guide 165 Table 56. Intel 820E Chipset Platform Clock Skews NOTES: Intel 820E Chipset 166 Design Guide The following figure shows the Intel 820E chipset clock length routing guidelines. Figure 87. Intel 820E Chipset Clock Routing Guidelines1,2 Intel 820E Chipset Design Guide 167 Table 57. Intel 820E Chipset Platform System Clock Cross-Reference CK133/DRCG Pin Name Component Pin Name 4.2. Component Placement and Interconnection Layout Requirements 4.2.1. 14.318 MHz Crystal to CK133 4.2.2. CK133 to DRCG Intel 820E Chipset 4.2.3. MCH to DRCG PclkM PclkN VddIPD Figure 89. MCH-to-DRCG Routing Diagram Figure 90. Direct RDRAM* Clock Routing Dimensions RIMM_0 RIMM_1 4.2.4. DRCG-to-RDRAM Channel Trace Geometry 4.2.5. Trace Length Intel 820E Chipset Design Guide 171 CFM/CFM# signal trace (sections A+B) is 2 mils. (Exact length matching is recommended.) 4.3. DRCG Impedance Matching Circuit Figure 94. DRCG Impedance Matching Network Table 59. External DRCG Component Values1,2 Component Nominal Value Notes 4.4. AGP Clock Routing Guidelines 4.5. Clock Routing Guidelines for Intel PGA370 Designs For the Intel 820E chipset/FC-PGA clock routing guidelines, refer to th e Guide Addendum for the Intel Pentium III Processor for the PGA370 Socket. These guidelines can be 4.6. Series Termination Resistors for CK133 Clock Outputs 4.7. Unused Outputs 4.8. Decoupling Recommendation for CK133 and DRCG 4.9. DRCG Frequency Selection and the DRCG+ 4.9.1. DRCG Frequency Selection Table and Jitter Specification 4.9.2. DRCG+ Frequency Selection Schematic 5. System Manufacturing 5.1. Stack-Up Requirement H 5.1.1. PCB Materials ST 5.1.2. Design Process 5.1.3. Test Coupon Design Guidelines 5.1.4. Recommended Stack-Up 5.1.5. Inner-Layer Routing 5.1.6. Impedance Calculation Tools 5.1.7. Testing Board Impedance 5.1.8. Board Impedance/Stack-up Summary ~48-mil core Not Routable Page 6. System Design Considerations 6.1. Power Delivery 6.1.1. Terminology and Definitions Intel 820E Chipset 6.1.2. Power Delivery of Intel 820E Chipset Customer Reference Board Figure 101. Intel 820E Chipset Power Delivery Example 5 V Dual Switch VCCVID VTT VCC 2.5 2.5 VBSY 1.8 V V 3.3VSB 1.8 VSB 2.5 V 6.1.3. ICH2 1.8 V / 3.3 V Power Sequencing 6.1.4. 3.3V/V5REF Sequencing 6.1.5. Excessive Power Consumption by 64/72-Mbit RDRAM 6.1.5.1. Option 1: Reduce the Clock Frequency During Initialization 6.1.5.2. Option 2: Increase the Current Capability of the 2.5 V Voltage Regulator 6.2. ICH2 Power Plane Split 6.3. Thermal Design Power 6.4. Glue Chip 3 (Intel 820E Chipset Glue Chip) Features Page Appendix A: Reference Design Schematics (Uniprocessor) Reference Design Feature Set Page REVISION 0.5 FCPGA 2 RIMM ICH2 REFERENCE SCHEMATICS Note that these schematics are preliminary and are subject to change. INTEL(R) 820E CHIPSET Block Diagram Device Table VID0 370-PIN SOCKET SKT1 VID3 GND;F36,A37,AC33,Y37 GND;AM22,AJ23,D22,F24,B24,AM26,AJ27,D26,F28,B28,AM30,D30,AF32,AB32,X32,T32 370-PIN SOCKET 4.7UH ITP Test Port Option 1% 110 Clock Synthesizer 1 OUT IN Active 133MHz,48MHz PLL inactive Disabled OUT Enabled* IN Sprd Spect JP14 MCH GTLREFB RAMREFA RAMREFB AGPREF MCH MMBT3904LT1 ICH2 ICH 2 U21 ICH2 CR8 VCCPU2 VCCPU1 VCCRTC FWH Top Block Lock R310 R304 0.1UF RIMM Sockets VCC2_5SBY;A41,A42,A54,A58,B41,B42,B54,B58 RSV_EXP: RSV_SPARE: GND;A1,A3,A5,A7,A9,A11,A13,A15,A17,A29,A21,A23,A25,A27,A19,A31, A33,A39 SIO KYBD/MSE I/F Super I/O CLOCKS INFRARED I/F AC97 Audio 44 VREFOUT VREF RX3D AC97 Audio Microphone Input CD Analog Input C24 Line_In Analog Input Communication And Network Riser (CNR) R60 EEPROMLAN R59 R75 ICH2 AC97 AND CNR LINK STUFFING OPTIONS Stuffing Option for Stuff for LAN Down Stuff for CNR Stuff for CNR Stuff for LAN Down LAN (82562EH) 27 29 36 40 LAN (82562ET/EM) LAN (RJ11 For 82562EH) LAN (RJ45 For 82562ET/EM) 25MHZ LAN STUFFING FOR EEPROM (U22) 82562EM A05723-001 82562ET A05441-001 20MHZ LAN STUFF FOR 82562EH STUFF FOR GILAD ONLY NOTES: STUFF FOR 82562ET/EM ONLYAND 82562ET/EM System 14 R253 R358 R246 AGP Connector 0 and 1 PCI Connectors 2 and 3 PCI Connectors IDE Connectors L7 USB Connectors C40 C41 C42 L6 Parallel Port 45 RP1 RP2 RP3 Serial Ports GND_KBMS_FB Keyboard/Mouse/Floppy J1 9 14 PS/2 KybdPS/2 Mse 10 Game Port VRM VRM requirements are based on VRM8.4 spec . C104 Voltage Regulators C268 + + C124 VTT 1.5 VOLTAGE REGULATOR Voltage Regulators C425 VCC 3.3 Standby Voltage Regulator SENSE- C424 Power Connector 98 13 12 6 5 R347 AGTL Termination HD#45 HD#8 HD#0 HD#9 PCI/AGP Pullups/Pulldowns PROCESSOR PCI Rambus* Termination 1011 Un-used Gates Backside No Stuff Decoupling Revision History Hub Interface Connector For debug only.