Intel 815EG Guide

Intel®815EG Chipset Platform
For Use with Universal Socket 370
Design Guide
August 2002
Document Number: 298301-002
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Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Intel reserves these for
future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.
The Intel815 chipset may contain design defects or errors known as errata which may cause the product to deviate from published specifications.
Current characterized errata are available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
I2C is a two-wire communications bus/protocol developed by Philips. SMBus is a subset of the I2C bus/protocol and was developed by Intel.
Implementations of the I2C bus/protocol may require licenses from various entities, including Philips Electronics N.V. and North American Philips
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Intel, Celeron, Pentium, MMX and the Intel logo are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States
and other countries.
*Other names and brands may be claimed as the property of others.
Copyright©2001-2002, Intel Corporation

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Contents
1Introduction ........................................................................................................................13
1.1 Design Guide and Chipset Basic Information .......................................................13
1.2 Terminology ..........................................................................................................14
1.3 Reference Documents ..........................................................................................16
1.4 System Overview ..................................................................................................17
1.4.1 System Features ...................................................................................18
1.4.2 Component Features.............................................................................19
1.4.2.1 Intel®82815EG GMCH Features .........................................19
1.4.2.2 Intel®815 to 815G/EG Signal Name Changes ....................20
1.4.2.3 Intel®82801BA I/O Controller Hub 2 (ICH2) ........................21
1.4.2.4 Firmware Hub (FWH)...........................................................21
1.4.3 Platform Initiatives .................................................................................21
1.4.3.1 Universal Motherboard Design ............................................21
1.4.3.2 Intel®PC 133........................................................................22
1.4.3.3 Accelerated Hub Architecture Interface ...............................22
1.4.3.4 Internet Streaming SIMD Extensions...................................22
1.4.3.5 Integrated LAN Controller ....................................................22
1.4.3.6 Ultra ATA/100 Support.........................................................22
1.4.3.7 Expanded USB Support .......................................................22
1.4.3.8 Manageability and Other Enhancements .............................23
1.4.3.9 AC ’97 6-Channel Support ...................................................23
1.4.3.10 Low-Pin-Count (LPC) Interface............................................26
2General Design Considerations.........................................................................................27
2.1 Nominal Board Stack-Up ......................................................................................27
2.2 Future Designs Require Pull-Ups and Pull-Downs on Any Unused Input and
I/O Pins .................................................................................................................28
2.3 Support For P-MOS Kicker “ON”: SMAA[9] Is Strapped High by an Internal
50 kΩPull-Up Resistor .........................................................................................28
2.4 Electrostatic Discharge Platform Recommendations ...........................................28
3Component Layouts...........................................................................................................31
4Universal Socket 370 Design ............................................................................................35
4.1 Universal Socket 370 Definitions ..........................................................................35
4.2 Processor Design Requirements ..........................................................................37
4.2.1 Use of Universal Socket 370 Design with Incompatible GMCH............37
4.2.2 Identifying the Processor at the Socket.................................................38
4.2.3 Setting the Appropriate Processor VTT Level .......................................39
4.2.4 VTT Processor Pin AG1........................................................................40
4.2.5 Identifying the Processor at the GMCH.................................................41
4.2.6 Configuring Non-VTT Processor Pins ...................................................42
4.2.7 VCMOS Reference................................................................................43
4.2.8 Processor Signal PWRGOOD...............................................................44
4.2.9 APIC Clock Voltage Switching Requirements .......................................45
4.2.10 GTLREF Topology and Layout..............................................................46

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4.3 Power Sequencing on Wake Events ....................................................................47
4.3.1 Gating of Intel®CK-815 to VTTPWRGD ...............................................47
4.3.2 Gating of PWROK to Intel®ICH2 ..........................................................48
5System Bus Design Guidelines .........................................................................................49
5.1 System Bus Routing Guidelines ...........................................................................49
5.1.1 Initial Timing Analysis ............................................................................49
5.2 General Topology and Layout Guidelines.............................................................52
5.2.1 Motherboard Layout Rules for AGTL/AGTL+ Signals ...........................53
5.2.1.1 Ground Reference ...............................................................53
5.2.1.2 Reference Plane Splits ........................................................53
5.2.1.3 Processor Connector Breakout............................................53
5.2.1.4 Minimizing Crosstalk ............................................................54
5.2.2 Motherboard Layout Rules for Non-AGTL/AGTL+ (CMOS) Signals .....55
5.2.3 THRMDP and THRMDN .......................................................................56
5.2.4 Additional Routing and Placement Considerations ...............................56
5.3 Electrical Differences for Universal PGA370 Designs ..........................................57
5.3.1 THERMTRIP Circuit ..............................................................................57
5.3.1.1 THERMTRIP Timing ............................................................58
5.3.1.2 THERMTRIP Support for 0.13 Micron Technology
Processors, A-1 Stepping ....................................................58
5.4 PGA370 Socket Definition Details ........................................................................59
5.5 BSEL[1:0] Implementation Differences.................................................................62
5.6 CLKREF Circuit Implementation ...........................................................................63
5.7 Undershoot/Overshoot Requirements ..................................................................64
5.8 Processor Reset Requirements............................................................................65
5.9 Processor PLL Filter Recommendations ..............................................................66
5.9.1 Topology................................................................................................66
5.9.2 Filter Specification .................................................................................66
5.9.3 Recommendation for Intel®Platforms ...................................................68
5.9.4 Custom Solutions ..................................................................................70
5.10 Voltage Regulation Guidelines..............................................................................70
5.11 Decoupling Guidelines for Universal PGA370 Designs ........................................70
5.11.1 VCCCORE Decoupling Design .................................................................70
5.11.2 VTT Decoupling Design ........................................................................71
5.11.3 VREF Decoupling Design......................................................................71
5.12 Thermal Considerations........................................................................................72
5.12.1 Heatsink Volumetric Keep-Out Regions................................................72
5.12.2 Fan Heatsink Keep-Out Adherence for Future Boxed Intel®Celeron®
Processors ............................................................................................74
5.13 Debug Port Changes ............................................................................................75
6System Memory Design Guidelines...................................................................................77
6.1 System Memory Routing Guidelines.....................................................................77
6.2 System Memory 2-DIMM Design Guidelines ........................................................78
6.2.1 System Memory 2-DIMM Connectivity ..................................................78
6.2.2 System Memory 2-DIMM Layout Guidelines .........................................79
6.3 System Memory 3-DIMM Design Guidelines ........................................................81
6.3.1 System Memory 3-DIMM Connectivity ..................................................81
6.3.2 System Memory 3-DIMM Layout Guidelines .........................................82
6.4 System Memory Decoupling Guidelines ...............................................................83

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6.5 Compensation.......................................................................................................85
7Display Cache Design Guidelines .....................................................................................87
7.1 Display Cache Interface........................................................................................87
7.2 GPA Card Considerations.....................................................................................87
7.3 GPA Mechanical Considerations ..........................................................................87
7.4 Display Cache Clocking ........................................................................................88
7.5 VDDQ Generation.................................................................................................88
8Integrated Graphics Display Output...................................................................................89
8.1 Analog RGB/CRT..................................................................................................89
8.1.1 RAMDAC/Display Interface ...................................................................89
8.1.2 Reference Resistor (Rset) Calculation..................................................91
8.1.3 RAMDAC Board Design Guidelines ......................................................91
8.1.4 RAMDAC Layout Recommendations ....................................................93
8.1.5 HSYNC/VSYNC Output Guidelines.......................................................93
8.2 Intel®Digital Video Out..........................................................................................94
8.2.1 Intel®DVO Interface Routing Guidelines...............................................94
8.2.2 Intel®DVO I2C Interface Considerations ...............................................94
8.2.3 Leaving the Intel®DVO Port Unconnected............................................94
9Hub Interface .....................................................................................................................97
9.1.1 Data Signals ..........................................................................................98
9.1.2 Strobe Signals .......................................................................................98
9.1.3 HREF Generation/Distribution...............................................................98
9.1.4 Compensation .......................................................................................99
10 I/O Controller Hub 2 (Intel®ICH2)....................................................................................101
10.1 Decoupling ..........................................................................................................101
10.2 Power Sequencing on Wake Events ..................................................................102
10.3 Power Supply PS_ON Considerations................................................................103
11 I/O Subsystem .................................................................................................................105
11.1 IDE Interface .......................................................................................................105
11.1.1 Cabling ................................................................................................105
11.2 Cable Detection for Ultra ATA/66 and Ultra ATA/100 .........................................105
11.2.1 Combination Host-Side/Device-Side Cable Detection ........................106
11.2.2 Device-Side Cable Detection...............................................................107
11.2.3 Primary IDE Connector Requirements ................................................108
11.2.4 Secondary IDE Connector Requirements ...........................................109
11.3 AC ’97 .................................................................................................................110
11.3.1 Communications Network Riser (CNR)...............................................111
11.3.2 AC ’97 Audio Codec Detect Circuit and Configuration Options...........112
11.3.2.1 Valid Codec Configurations ...............................................115
11.3.3 SPKR Pin Considerations....................................................................115
11.3.4 AC ’97 Routing ....................................................................................116
11.3.5 Motherboard Implementation ..............................................................117
11.4 USB.....................................................................................................................118
11.4.1 Using Native USB Interface.................................................................118
11.4.2 Disabling the Native USB Interface of ICH2........................................119
11.5 I/O APIC Design Recommendation ....................................................................119
11.5.1 PIRQ Routing Example .......................................................................120

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11.6 SMBus/SMLink Interface ....................................................................................121
11.6.1 SMBus Architecture and Design Considerations ................................122
11.6.1.1 General Design Issues and Notes .....................................122
11.7 PCI ......................................................................................................................125
11.8 RTC.....................................................................................................................126
11.8.1 RTC Crystal.........................................................................................126
11.8.2 External Capacitors .............................................................................127
11.8.3 RTC Layout Considerations ................................................................127
11.8.4 RTC External Battery Connection .......................................................127
11.8.5 RTC External RTCRST Circuit............................................................129
11.8.6 Power-Well Isolation Control Requirements .......................................129
11.8.7 RTC Routing Guidelines......................................................................130
11.8.8 VBIAS DC Voltage and Noise Measurements ....................................131
11.9 LAN Layout Guidelines .......................................................................................131
11.9.1 Intel®ICH2 – LAN Interconnect Guidelines .........................................132
11.9.1.1 Bus Topologies ..................................................................133
11.9.1.2 Point-to-Point Interconnect ................................................133
11.9.1.3 LOM/CNR Interconnect......................................................134
11.9.1.4 Signal Routing and Layout .................................................135
11.9.1.5 Crosstalk Consideration.....................................................135
11.9.1.6 Impedances .......................................................................135
11.9.1.7 Line Termination ................................................................136
11.9.2 General LAN Routing Guidelines and Considerations ........................136
11.9.2.1 General Trace Routing Considerations..............................136
11.9.2.2 Power and Ground Connections........................................138
11.9.2.3 A 4-Layer Board Design.....................................................139
11.9.2.4 Common Physical Layout Issues .......................................139
11.9.3 Intel®82562EH Home/PNA* Guidelines..............................................141
11.9.3.1 Power and Ground Connections........................................141
11.9.3.2 Guidelines for Intel®82562EH Component Placement......141
11.9.3.3 Crystals and Oscillators .....................................................142
11.9.3.4 Phoneline HPNA Termination ............................................142
11.9.3.5 Critical Dimensions ............................................................143
11.9.4 Intel®82562ET / Intel®82562EM Guidelines ......................................144
11.9.4.1 Guidelines for Intel®82562ET / Intel®82562EM Component
Placement ..........................................................................144
11.9.4.2 Crystals and Oscillators .....................................................145
11.9.4.3 Intel®82562ET / Intel®82562EM Termination Resistors...145
11.9.4.4 Critical Dimensions ............................................................145
11.9.4.5 Reducing Circuit Inductance ..............................................147
11.9.5 Intel®82562ET/82562EM Disable Guidelines .....................................148
11.9.6 Intel®82562ET / Intel®82562EH Dual Footprint Guidelines ...............149
11.10 LPC/FWH............................................................................................................151
11.10.1 In-Circuit FWH Programming..............................................................151
11.10.2 FWH VPP Design Guidelines ...............................................................151
11.10.3 FWH Decoupling .................................................................................152
12 Clocking...........................................................................................................................153
12.1 2-DIMM Clocking ................................................................................................153
12.2 3-DIMM Clocking ................................................................................................155
12.3 Clock Routing Guidelines....................................................................................157
12.4 Clock Driver Frequency Strapping ......................................................................159

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12.5 Clock Skew Assumptions ...................................................................................160
12.6 Intel®CK-815 Power Gating On Wake Events ...................................................161
13 Power Delivery.................................................................................................................163
13.1 Power Delivery Guidelines ..................................................................................163
13.1.1 5V Dual Switch ....................................................................................165
13.1.2 VTT......................................................................................................165
13.1.3 1.85 V ..................................................................................................165
13.1.4 VDDQ ..................................................................................................165
13.1.5 3.3VSB ................................................................................................166
13.1.6 1.85VSB ..............................................................................................166
13.1.7 VCMOS ...............................................................................................166
13.2 Thermal Design Power .......................................................................................167
13.2.1 Pull-Up and Pull-Down Resistor Values ..............................................167
13.3 ATX Power Supply PWRGOOD Requirements..................................................168
13.4 Power Management Signals ...............................................................................168
13.4.1 Power Button Implementation .............................................................169
13.4.2 1.85 V/3.3 V Power Sequencing..........................................................170
13.4.3 V5REF/3.3 V Sequencing....................................................................171
13.5 Power Plane Splits ..............................................................................................172
13.6 Glue Chip 3 (ICH2 Glue Chip) ............................................................................173
14 System Design Checklist.................................................................................................175
14.1 Design Review Checklist ....................................................................................175
14.2 Processor Checklist ............................................................................................175
14.2.1 GTL Checklist......................................................................................175
14.2.2 CMOS Checklist ..................................................................................176
14.2.3 TAP Checklist for 370-Pin Socket Processors ....................................176
14.2.4 Miscellaneous Checklist for 370-Pin Socket Processors ....................177
14.3 GMCH Checklist .................................................................................................178
14.3.1 System Memory Interface Checklist....................................................178
14.3.2 Hub Interface Checklist .......................................................................178
14.3.3 Digital Video Output Port Checklist .....................................................179
14.4 Intel®ICH2 Checklist...........................................................................................179
14.4.1 PCI Interface .......................................................................................179
14.4.2 Hub Interface.......................................................................................179
14.4.3 LAN Interface ......................................................................................180
14.4.4 EEPROM Interface..............................................................................180
14.4.5 FWH/LPC Interface .............................................................................180
14.4.6 Interrupt Interface ................................................................................180
14.4.7 GPIO Checklist....................................................................................182
14.4.8 USB .....................................................................................................182
14.4.9 Power Management ............................................................................183
14.4.10 Processor Signals ...............................................................................184
14.4.11 System Management ..........................................................................184
14.4.12 RTC ...........................................................................................184
14.4.13 AC ’97 ...........................................................................................185
14.4.14 Miscellaneous Signals .........................................................................186
14.4.15 Power ...........................................................................................187
14.4.16 IDE Checklist.......................................................................................188
14.5 LPC Checklist .....................................................................................................190
14.6 System Checklist ................................................................................................191

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14.7 FWH Checklist ....................................................................................................191
14.8 Clock Synthesizer Checklist................................................................................192
14.9 System Memory Checklist ..................................................................................193
14.10 Power Delivery Checklist ....................................................................................193
15 Third-Party Vendor Information .......................................................................................195

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Figures
Figure 1. System Block Diagram .......................................................................................18
Figure 2. Component Block Diagram ................................................................................19
Figure 3. AC ’97 Audio and Modem Connections .............................................................25
Figure 4. Board Construction Example for 60 ΩNominal Stack-up ..................................27
Figure 5. Top Signal Layer before the Ground Fill Near the I/O Layer ..............................29
Figure 6. Top Signal Layer after the Ground Fill Near the I/O Layer .................................29
Figure 7. Bottom Signal Layer before the Ground Fill Near the I/O Area ..........................30
Figure 8. Bottom Signal Layer after the Ground Fill Near the I/O......................................30
Figure 9. GMCH 544-Ball µBGA* CSP Quadrant Layout (Top View)................................31
Figure 10. ICH2 360-Ball EBGA Quadrant Layout (Top View) ..........................................32
Figure 11. Firmware Hub (FWH) Packages ......................................................................33
Figure 12. Future 0.13 Micron Socket 370 Processor Safeguard for Universal Socket 370
Designs Using A-2 GMCH..........................................................................................37
Figure 13. Processor Detect Mechanism at Socket/TUAL5 Generation Circuit ................38
Figure 14. VTT Selection Switch ........................................................................................39
Figure 15. Switching Pin AG1............................................................................................40
Figure 16. Processor Identification Strap on GMCH .........................................................41
Figure 17. VTTPWRGD Configuration Circuit ...................................................................42
Figure 18. GTL_REF/VCMOS_REF Voltage Divider Network ..........................................43
Figure 19. Resistor Divider Network for Processor PWRGOOD.......................................44
Figure 20 Voltage Switch for Processor APIC Clock.........................................................45
Figure 21. GTLREF Circuit Topology ................................................................................46
Figure 22. Gating Power to Intel®CK-815 .........................................................................47
Figure 23 PWROK Gating Circuit for Intel®ICH2..............................................................48
Figure 24. Topology for 370-Pin Socket Designs with Single-Ended Termination (SET)..52
Figure 25. AGTL/AGTL+ Trace Routing............................................................................53
Figure 26. Routing for THRMDP and THRMDN................................................................56
Figure 27. Example Implementation of THERMTRIP Circuit ............................................57
Figure 28 Thermtrip Support for A-1 Stepping 0.13 Micron Technology Processors........59
Figure 29. BSEL[1:0] Circuit Implementation for PGA370 Designs...................................63
Figure 30. Examples for CLKREF Divider Circuit..............................................................64
Figure 31. RESET#/RESET2# Routing Guidelines ...........................................................65
Figure 32. Filter Specification ............................................................................................67
Figure 33. Example PLL Filter Using a Discrete Resistor .................................................69
Figure 34. Example PLL Filter Using a Buried Resistor ....................................................69
Figure 35. Core Reference Model .....................................................................................70
Figure 36. Capacitor Placement on the Motherboard........................................................71
Figure 37. Heatsink Volumetric Keep-Out Regions...........................................................73
Figure 38 Motherboard Component Keep-Out Regions....................................................73
Figure 39. Keep-Out Requirements for the 370-pin (Top View)........................................74
Figure 40. TAP Connector Comparison ............................................................................75
Figure 41. System Memory Routing Guidelines ................................................................77
Figure 42. System Memory Connectivity (2 DIMM) ...........................................................78
Figure 43. System Memory 2-DIMM Routing Topologies..................................................79
Figure 44. System Memory Routing Example ...................................................................80
Figure 45. System Memory Connectivity (3 DIMM) ...........................................................81
Figure 46. System Memory 3-DIMM Routing Topologies..................................................82
Figure 47. Intel815 Chipset Platform Decoupling Example ............................................83
Figure 48. Intel®815 Chipset Decoupling Example...........................................................84
Figure 49. Display Cache Input Clocking...........................................................................88

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Figure 50. Schematic of RAMDAC Video Interface...........................................................90
Figure 51. Cross-Sectional View of a Four-Layer Board ...................................................91
Figure 52. Recommended RAMDAC Component Placement and Routing ......................92
Figure 53. Recommended RAMDAC Reference Resistor Placement and Connections ..93
Figure 54. Hub Interface Signal Routing Example ............................................................97
Figure 55. Single Hub Interface Reference Divider Circuit................................................99
Figure 56. Locally Generated Hub Interface Reference Dividers ......................................99
Figure 57. Intel®ICH2 Decoupling Capacitor Layout.......................................................102
Figure 58. Combination Host-Side / Device-Side IDE Cable Detection ..........................106
Figure 59. Device-Side IDE Cable Detection...................................................................107
Figure 60. Connection Requirements for Primary IDE Connector...................................108
Figure 61. Connection Requirements for Secondary IDE Connector..............................109
Figure 62. Intel®ICH2 AC ’97– Codec Connection .........................................................110
Figure 63. CNR Interface.................................................................................................111
Figure 64. CDC_DN_ENAB# Support Circuitry for a Single Codec on Motherboard......112
Figure 65. CDC_DN_ENAB# Support Circuitry for Multi-Channel Audio Upgrade..........113
Figure 66. CDC_DN_ENAB# Support Circuitry for Two-Codecs on Motherboard /
One-Codec on CNR .................................................................................................114
Figure 67. CDC_DN_ENAB# Support for Two-Codecs on Motherboard /
Two-Codecs on CNR ...............................................................................................114
Figure 68. Example Speaker Circuit................................................................................116
Figure 69. USB Data Signals...........................................................................................119
Figure 70. Example PIRQ Routing ..................................................................................120
Figure 71. SMBus/SMLink Interface................................................................................121
Figure 72. Unified VCC_Suspend Architecture ...............................................................123
Figure 73. Unified VCCCORE Architecture.........................................................................123
Figure 74. Mixed VCC_Suspend/VCCCORE Architecture .................................................124
Figure 75. PCI Bus Layout Example................................................................................125
Figure 76. External Circuitry for the ICH2 RTC ...............................................................126
Figure 77. Diode Circuit to Connect RTC External Battery..............................................128
Figure 78. RTCRST External Circuit for ICH2 RTC ........................................................129
Figure 79. RTC Power Well Isolation Control..................................................................130
Figure 80. Intel®ICH2 / LAN Connect Section ................................................................132
Figure 81. Single-Solution Interconnect...........................................................................133
Figure 82. LOM/CNR Interconnect ..................................................................................134
Figure 83. LAN_CLK Routing Example ...........................................................................135
Figure 84. Trace Routing.................................................................................................137
Figure 85. Ground Plane Separation ...............................................................................138
Figure 86. Intel®82562EH Termination ...........................................................................142
Figure 87. Critical Dimensions for Component Placement..............................................143
Figure 88. Intel®82562ET/Intel®82562EM Termination .................................................145
Figure 89. Critical Dimensions for Component Placement..............................................146
Figure 90. Termination Plane ..........................................................................................148
Figure 91. Intel®82562ET/82562EM Disable Circuit.......................................................148
Figure 92. Dual-Footprint LAN Connect Interface ...........................................................149
Figure 93. Dual-Footprint Analog Interface .....................................................................149
Figure 94. FWH VPP Isolation Circuitry ..........................................................................151
Figure 95. Platform Clock Architecture for a 2-DIMM Solution........................................154
Figure 96. Platform Clock Architecture for a 3-DIMM Solution........................................156
Figure 97. Clock Routing Topologies ..............................................................................157
Figure 98. Power Delivery Map........................................................................................164
Figure 99. Pull-Up Resistor Example ..............................................................................167
Figure 100. Example 1.85 V/3.3 V Power Sequencing Circuit ........................................170
Figure 101. V5REF/3.3 V Sequencing Circuitry ..............................................................171

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Figure 102. Power Plane Split Example ..........................................................................172
Figure 103. USB Data Line Schematic............................................................................183
Figure 104. Intel®ICH2 Oscillator Circuitry......................................................................185
Figure 105. SPKR Circuitry..............................................................................................186
Figure 106. V5REF Circuitry............................................................................................187
Figure 107. Host/Device Side Detection Circuitry............................................................189
Figure 108. Device Side Only Cable Detection ...............................................................189
Tables
Table 1. Intel®82815 to Intel®82815G Pin Name Changes..............................................20
Table 2. Processor Considerations for Universal Socket 370 Design...............................35
Table 3. GMCH Considerations for Universal Socket 370 Design ....................................36
Table 4. Intel®ICH2 Considerations for Universal Socket 370 Design .............................36
Table 5. Clock Synthesizer Considerations for Universal Socket 370 Design ..................37
Table 6. Determining the Installed Processor via Hardware Mechanisms ........................41
Table 7. Intel® Pentium®III Processor AGTL/AGTL+ Parameters for Example
Calculations ................................................................................................................50
Table 8. Example TFLT_MAX Calculations for 133 MHz Bus ................................................51
Table 9. Example TFLT_MIN Calculations (Frequency Independent) ....................................51
Table 10. Trace Guidelines for Figure 24 ..........................................................................52
Table 11. Trace Width: Space Guidelines.........................................................................52
Table 12. Routing Guidelines for Non-AGTL/AGTL+ Signals ...........................................55
Table 13. Processor Pin Definition Comparison................................................................59
Table 14. Resistor Values for CLKREF Divider (3.3 V Source).........................................64
Table 15. RESET#/RESET2# Routing Guidelines (see Figure 31)...................................65
Table 16. Component Recommendations – Inductor........................................................68
Table 17. Component Recommendations – Capacitor .....................................................68
Table 18. Component Recommendation – Resistor .........................................................68
Table 19. System Memory 2-DIMM Solution Space..........................................................79
Table 20. System Memory 3-DIMM Solution Space..........................................................82
Table 21. Decoupling Capacitor Recommendation.........................................................101
Table 22. Signal Descriptions ..........................................................................................115
Table 23. Codec Configurations ......................................................................................115
Table 24. IOAPIC Interrupt Inputs 16 thru 23 Usage.......................................................120
Table 25. Pull-Up Requirements for SMBus and SMLink................................................122
Table 26. LAN Connect ...................................................................................................131
Table 27. Single-Solution Interconnect Length Requirements (See Figure 81) ..............133
Table 28. LOM/CNR Length Requirements (See Figure 82)...........................................134
Table 29. Critical Dimensions for Component Placement (Refer to Figure 87) ..............143
Table 30. Critical Dimensions for Component Placement (see Figure 89) .....................146
Table 31. Intel®82562ET Operating States.....................................................................149
Table 32. Intel®CK-815 (2-DIMM) Clocks.......................................................................153
Table 33. Intel®CK-815 (3-DIMM) Clocks.......................................................................155
Table 34. Simulated Clock Routing Solution Space ........................................................158
Table 35. Simulated Clock Skew Assumptions ...............................................................160
Table 36. Power Delivery Definitions...............................................................................163

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Revision History
Rev. No. Description Rev. Date
-001 • Initial Release. Sept 2001
-002 • Added Section 2.4, Electrostatic Discharge Platform
Recommendations
• Replaced Figure 98, Power Delivery Map, in Section 13, Power
Delivery
• Revised Section 13.4.3, 3.3V/V5REF Sequencing
• Revised Table 33. Intel®CK-815 (3-DIMM) Clocks, Intel®CK-815
(3-DIMM) Clocks, in Section 12.2, 3-DIMM Clocking
• Revised Table 32, Intel®CK-815 (2-DIMM) Clocks, in Section
12.1, 2-DIMM Clocking
• Replaced Figure 79, RTC Power Well Isolation Control, in Section
11.8.6, Power Well Isolation Control Requirements
• Replaced Figure 84, Trace Routing, in Section 11.9.2.1, General
Trace Routing Considerations
• Revised Section 13.4.3, 3.3V/V5REF Sequencing
• Revised Checklist Recommendations for 5V_REF_SUS in
Section 14.4.15, Power
• Added SUSCLK to the RTC Checklist in Section 14.4.12
• Added Section 10.3 Power Supply PS_ON Considerations
Aug 2002

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Intel®815EG Chipset Platform Design Guide 13
1 Introduction
1.1 Design Guide and Chipset Basic Information
This design guide organizes Intel design recommendations for the Intel®815EG chipset platform
for use with universal socket 370. In addition to providing motherboard design recommendations
(e.g., layout and routing guidelines), this document also addresses system design issues (e.g.,
thermal requirements) for the chipset platform.
This design guide contains design recommendations, debug recommendations, and a system
checklist. These design guidelines are developed to ensure maximum flexibility for board
designers while reducing the risk of board-related issues.
Consult the debug recommendations when debugging your design. However, these debug
recommendations should be understood before completing board design to ensure that the debug
port, in addition to other debug features, are implemented correctly.
There is no AGP port capability in the Intel®82815EG GMCH. The 82815EG uses internal
graphics only.
There are six chipsets in the Intel 815 chipset family:
• Intel® 82815 chipset: This chipset contains the Intel 82815 and the Intel® 82801AA ICH.
• Intel® 82815E chipset: This chipset contains the Intel 82815E and the Intel® 82801BA ICH2.
• Intel® 82815P chipset: This chipset contains the Intel 82815P and the 82801AA ICH. There is
no internal graphics capability. This GMCH uses an AGP port only.
• Intel® 82815EP chipset: This chipset contains the Intel 82815EP and the 82801BA ICH2.
There is no internal graphics capability. This GMCH uses an AGP port only.
• Intel® 82815G chipset: This chipset contains the 82815G GMCH and 82801AA ICH. There is
no AGP port capability. This GMCH uses internal graphics only.
• Intel® 82815EG chipset. This chipset contains the 82815EG GMCH and Intel 82801BA
ICH2. There is no AGP port capability. This GMCH uses internal graphics only.
The only component difference between the 82815 GMCH and the 82815E GMCH is the I/O
Controller Hub. The only component difference between the 82815P GMCH and the 82815EP
GMCH is the I/O Controller Hub. The only component difference between the 82815G GMCH
and the 82815EG GMCH is the I/O Controller Hub.
The Intel 815EG chipset platform supports the following processors:
• Intel® Pentium®III processor based on 0.18 micron technology (CPUID = 068xh).
• Intel® Celeron®processor based on 0.18 micron technology (CPUID = 068xh). This applies to
Celeron 533A MHz and ≥566 MHz processors
• Future 0.13 micron socket 370 processors

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14 Intel®815EG Chipset Platform Design Guide
The system bus speed supported by the design is based on the capabilities of the processor,
chipset, and clock driver.
The 815 chipset for use with the universal socket 370 is not compatible with the
Intel®Pentium®II processor (CPUID = 066xh) 370-pin socket.
1.2 Terminology
This section describes some of the terms used in this document. Additional power delivery term
definitions are provided at the beginning of Chapter13, “Power Delivery”.
Term Description
AGP Accelerated Graphics Port
AGTL/AGTL+ Refers to processor bus signals that are implemented using either Assisted
Gunning Transceiver Logic (AGTL+) or its lower voltage variant (AGTL), depending
on which processor is being used.
Bus Agent A component or group of components that, when combined, represent a single load
on the AGTL+ bus.
Crosstalk The reception on a victim network of a signal imposed by aggressor network(s)
through inductive and capacitive coupling between the networks.
• Backward Crosstalk–coupling that creates a signal in a victim network that travels
in the opposite direction as the aggressor’s signal.
• Forward Crosstalk–coupling that creates a signal in a victim network that travels
in the same direction as the aggressor’s signal.
• Even Mode Crosstalk–coupling from single or multiple aggressors when all the
aggressors switch in the same direction that the victim is switching.
• Odd Mode Crosstalk–coupling from single or multiple aggressors when all the
aggressors switch in the opposite direction that the victim is switching.
GMCH Graphics and Memory Controller Hub. A component of the Intel 815 chipset
platform for use with the Universal Socket 370
ICH Intel 82801AA I/O Controller Hub component.
ISI Inter-symbol interference is the effect of a previous signal (or transition) on the
interconnect delay. For example, when a signal is transmitted down a line and the
reflections due to the transition have not completely dissipated, the following data
transition launched onto the bus is affected. ISI is dependent upon frequency, time
delay of the line, and the reflection coefficient at the driver and receiver. ISI can
impact both timing and signal integrity.
Network Length The distance between agent 0 pins and the agent pins at the far end of the bus.
Pad The electrical contact point of a semiconductor die to the package substrate. A pad
is only observable in simulation.
Pin The contact point of a component package to the traces on a substrate such as the
motherboard. Signal quality and timings can be measured at the pin.

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Intel®815EG Chipset Platform Design Guide 15
Term Description
Ringback The voltage that a signal rings back to after achieving its maximum absolute value.
Ringback may be due to reflections, driver oscillations, or other transmission line
phenomena.
Setup Window The time between the beginning of Setup to Clock (TSU_MIN) and the arrival of a
valid clock edge. This window may be different for each type of bus agent in the
system.
SSO Simultaneous Switching Output (SSO) Effects refers to the difference in electrical
timing parameters and degradation in signal quality caused by multiple signal
outputs simultaneously switching voltage levels (e.g., high-to-low) in the opposite
direction from a single signal (e.g., low-to-high) or in the same direction (e.g., high-
to-low). These are respectively called odd-mode switching and even-mode
switching. This simultaneous switching of multiple outputs creates higher current
swings that may cause additional propagation delay (or “push-out”), or a decrease
in propagation delay (or “pull-in”). These SSO effects may impact the setup and/or
hold times and are not always taken into account by simulations. System timing
budgets should include margin for SSO effects.
Stub The branch from the bus trunk terminating at the pad of an agent.
System Bus The system bus is the processor bus.
Trunk The main connection, excluding interconnect branches, from one end agent pad to
the other end agent pad.
Undershoot Minimum voltage observed for a signal to extend below VSS at the device pad.
Universal Socket 370 Refers to the Intel 815EG chipset using the “universal” PGA370 socket. In general,
these designs support 66/100/133 MHz system bus operation, Intel®VRM
guidelines for future 0.13 micron processors, and Celeron®processors
(CPUID=068xh), Pentium®III processor (CPUID=068xh), and future Celeron and
Pentium III processors using 0.13 micron technology in single-microprocessor
based designs.
Victim A network that receives a coupled crosstalk signal from another network is called
the victim network.

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16 Intel®815EG Chipset Platform Design Guide
1.3 Reference Documents
Document Document Number /
Location
Intel®815 Chipset Family: 82815G/82815EG Graphics and Memory Controller
Hub (GMCH) for use with the Universal Socket 370 Datasheet
Doc 290714
Intel developer website
Intel®82802AB/82802AC Firmware Hub (FWH) Datasheet Doc 290658
Intel developer website
Intel®82801BA I/O Controller Hub (ICH2) and Intel®82801BAM I/O Controller
Hub (ICH2-M) Datasheet
Doc 290687
Intel developer website
Intel®Pentium®III Processor Specification Update (latest revision from website) http://developer.intel.co
m/design/PentiumIII/sp
ecupdt/
AP 907 Intel®Pentium®III Processor Power Distribution Guidelines Doc 245085
Intel developer website
AP-585 Intel®Pentium®II Processor AGTL+ Guidelines Doc 243330
Intel developer website
AP-587 Intel®Pentium®II Processor Power Distribution Guidelines Doc 243332
Intel developer website
Accelerated Graphics Port Interface Specification, Revision 2.0 http://www.intel.com/te
chnology/agp/agp_inde
x.htm)
Graphics Performance Accelerator Specification ftp://download.intel.co
m/technology/agp/dow
nloads/agp20.pdf
PCI Local Bus Specification, Revision 2.2 http://www.pcisig.com/s
pecifications/conventio
nal_pci
AC ’97 Component Specification, Revision 2.2(1) http://developer.intel.co
m/ial/scalableplatforms
/audio/index.htm
Communication Network Riser Specification, Revision 1.1 http://developer.intel.co
m/technology/cnr/
Universal Serial Bus, Revision 2.0 Specification http://www.usb.org/dev
elopers/usb20/
NOTES:
1. Throughout this document, this specification will be referred to as AC ’97 v2.2.

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Intel®815EG Chipset Platform Design Guide 17
1.4 System Overview
The 815EG chipset platform for use with the universal socket 370 contains a Graphics and
Memory Controller Hub (GMCH) component and I/O Controller Hub 2 (ICH2) component for
desktop platforms.
The GMCH provides the processor interface (optimized for future 0.13 micron Celeron processors
and Pentium III processors (socket 370) and the Pentium III processors (CPUID = 068xh), DRAM
interface, hub interface, and internal graphics. It does not provide support for an external AGP
port. This product provides flexibility and scalability in memory subsystem performance. PC100
SDRAM system memory may be scaled to PC133 system memory.
The Accelerated Hub Architecture interface (i.e., the chipset component interconnect) is designed
into the chipset to provide an efficient, high-bandwidth communication channel between the
GMCH and the I/O controller hub. The chipset architecture also enables a security and
manageability infrastructure through the Firmware Hub component.
An ACPI-compliant 815EG chipset platform can support the Full-on (S0), Stop Grant (S1),
Suspend to RAM (S3), Suspend to Disk (S4), and Soft-off (S5) power management states. The
chipset also supports wake-on-LAN for remote administration and troubleshooting. The chipset
architecture removes the requirement for the ISA expansion bus that was traditionally integrated
into the I/O subsystem of PCIsets/AGPsets. This removes many of the conflicts experienced when
installing hardware and drivers into legacy ISA systems. The elimination of ISA provides true
plug-and-play for the platform. Traditionally, the ISA interface was used for audio and modem
devices. The addition of AC ’97 allows the OEM to use software-configurable AC ’97 audio and
modem coder/decoders (codecs), instead of the traditional ISA devices.

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18 Intel®815EG Chipset Platform Design Guide
1.4.1 System Features
The 815EG chipset platform contains two components: the 82815EG Graphics and Memory
Controller Hub (GMCH) and the 82801BA I/O Controller Hub 2 (ICH2). The GMCH integrates a
66/100/133 MHz, P6 family system bus controller, integrated 2D/3D graphics accelerator,
100/133 MHz SDRAM controller, and a high-speed accelerated hub architecture interface for
communication with the ICH2. The ICH2 integrates an UltraATA/100 controller, 2 Universal
Serial Bus (USB) host controllers with a total of 4 ports, Low Pin Count (LPC) interface
controller, Firmware Hub (FWH) interface controller, PCI interface controller, AC-link, integrated
LAN controller, and a hub interface for communication with the GMCH.
Figure 1. System Block Diagram
Sys_Blk_815E_B0
82815EG B-0
GMCH
82801BA ICH2
KBC/SIO
Display Cache
AIMM
(AGP in-line memory module)
Analog display out
Digital video out
66/100/133 MHz system bus
Hub interface
100/133 MHz
SDRAM
PCI slots
FWH
Flash BIOS
4x USB
2x IDE
Audio codec
Modem codec
AC97
LAN connect
component
LPC I/F
PCI bus
LAN
connect
815EG
Chipset
Intel Celeron and Pentium III
Processors Using 0.13 Micron
Technology

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Intel®815EG Chipset Platform Design Guide 19
1.4.2 Component Features
Figure 2. Component Block Diagram
System bus (66/100/133 MHz)
Processor I/F System
memory I/F
Local memory I/F
Hub I/F
Data
stream
control &
dispatch
Primary display
Overlay
H/W cursor
3D pipeline
2D (blit engine)
RAMDAC
FP / TVout
Internal graphics
Hub
SDRAM
100/133
MHz, 64 bit
Monitor
Digital
video out
comp_blk_1
GPA or AIMM
Card
1.4.2.1 Intel®82815EG GMCH Features
• Processor/System Bus Support
 Optimized for Celeron and Pentium III processors which use 0.13 micron technology at
133 MHz system bus frequency
 Support for Celeron and Pentium III processors (CPUID = 068xh); at 66 MHz system bus
frequency
 Supports 32-bit AGTL or AGTL+ bus addressing
 Supports uniprocessor systems
 Utilizes AGTL and AGTL+ bus driver technology (gated AGTL/AGTL+ receivers for
reduced power)
• Integrated DRAM controller
 32 MB to 512 MB using 16-Mb/64-Mb/128-Mb technology
 Supports up to three double-sided DIMMS (6 rows)
 100 MHz, 133 MHz SDRAM interface
 64-bit data interface
 Standard Synchronous DRAM (SDRAM) support (x-1-1-1 access)
 Supports only 3.3 V DIMM DRAM configurations
 No registered DIMM support
 Support for symmetrical and asymmetrical DRAM addressing
 Support for x8, x16 DRAM device widths
 Refresh mechanism: CAS-before-RAS only
 Support for DIMM serial PD (presence detect) scheme via SMbus interface
 Suspend-To-RAM (STR) power management support via self-refresh mode using CKE

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20 Intel®815EG Chipset Platform Design Guide
• Integrated Graphics Controller
 Full 2D/3D/DirectX acceleration
 Texture-mapped 3D with point sampled, bilinear, trilinear, and anisotropic filtering
 Hardware setup with support for strips and fans
 Hardware motion compensation assist for software MPEG/DVD decode
 Digital Video Out interface for support of digital displays and TV-Out
 PC99A/PC2001 compliant
 Integrated 230 MHz DAC
• Integrated Local Graphics Memory Controller (Display Cache)
 0 MB to 4 MB (via Graphics Performance Accelerator) using zero, one or two parts
 32-bit data interface
 133 MHz memory clock
 Supports only 3.3 V SDRAMs
• Packaging/Power
 544-ball mBGA CSP with local memory port
 1.85 V core and mixed 3.3 V, 1.5 V, and AGTL+ IO. Note that the 82801BA ICH2 has a
1.8 V requirement and the 82815EG GMCH has a 1.85 V requirement. Instead of using
separate voltage regulators to meet these requirements, a single voltage regulator can be
set to 1.795 V to 1.910 V. See Figure 98. Power Delivery Map.
1.4.2.2 Intel®815 to 815G/EG Signal Name Changes
Intel 82815G/EG pins associated with AGP signals have name changes. The following table shows
the old Intel 82815 signal name, the ball number, and the new Intel 82815G/EG signal name. New
designs for new 815G/EG boards should use pull-ups or pull-downs as indicated by the 815G/EG
signal name. 815 boards using 815GEG devices may leave the associated 815 pins in the original
815 configuration.
Table 1. Intel®82815 to Intel®82815G Pin Name Changes
Intel®815 Signal
Name Ball# Intel®815G/EG Signal Name
WBF# AB24 PU
AD_STB0 M22 PD
AD_STB0# L23 PU
AD_STB1 U22 PD
AD_STB1# V23 PU
SB_STB Y23 PD
SB_STB# AA24 PU
GRCOMP J26 PD40
AGPREF J24 0.5VDDQ
G_GNT# AD25 NC
G_AD[24] V25 PD
NOTES:
NC = No Connect. These pins should float
PU = Pull-up to 3.3 V through a weak pull-up resistor. (8.2 kΩto 10 kΩresistor.)
PD = Pull-down. These pins should be pulled down to ground through a weak pull- down resistor.
(8.2 kΩto 10 kΩresistor.)
PD40 = Pull-down to VSS using a 40  resistor.
0.5VDDQ = Set to 50% of the VDDQ voltage supply level.