Intel Pentium 4

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System Bus Routing

Intel

Pentium

4 Processor / Intel

850 Chipset Family Platform Design Guide 85

5.6 System Bus Routing Guidelines - Four-Layer

Motherboard

The following are descriptions and illustrations of system bus routing on the 4-layer customer

reference board.

Figure 52. Customer Reference Platform System Bus Routing – Top Layer

Top Layer

Data

Addr

Main Page

Table of Contents3
Introduction17
Related Documentation18
Conventions and Terminology19
Table 1. Platform Conventions and Terminology19
System Overview21
- Intel ® Pentium ® 4 Processor in the 478-Pin Package21
- System Configurations23
- Figure 1.Typical System Configuration23
Platform Initiatives24
- Intel ® 850 Chipset24
- Platform Manageability27
PC '99/'01 Platform Compliance28
Component Quadrant Layout29
- Processor Component Quadrant Layout29
- Figure 2. Processor Socket Quadrant Layout29
- Intel ® 850/850E Chipset Component Quadrant Layout30
- Figure 3. Intel ® 850/850E Chipset Quadrant Layout30
- Figure 4. Intel ® ICH2 Quadrant Layout30
Platform Placement and Stack-Up Overview31
- Platform Component Placement31
- Motherboard Layer Stack-Up36
Platform Clock Routing Guidelines39
- Figure 11. Clocking Architecture Using the CK0040
- Figure 12. Processor BCLK Topology41
- Routing Guidelines for System Bus Clocks41
- Figure 13. Source Shunt Termination42
- Table 5. BCLK [1:0] Routing Guidelines43
- Figure 14. Clock Skew as Measured from Agent to Agent45
- Figure 15. Trace Spacing45
- BCLK[1:0] Frequency Select46
- CK00 to Rambus DRCG* (Reference Clocks)48
- Figure 18. Vddir and 3Vmref Routing48
- Routing Guidelines for Rambus RDRAM* Device Clocks48
- Intel ® MCH to Rambus DRCG* (Phase Aligning Clocks)49
- Routing Guidelines for 66 Mhz and 33 Mhz Clocks56
System Bus Routing61
- Table 10. System Bus Routing Summary for the Processor61
- Return Path62
- Figure 32. GTLREF Routing63
- GTLREF Layout and Routing Recommendations63
- Processor Configuration64
  - Topology and Routing64
- Routing Guidelines for Asynchronous GTL+ and Other Signals71
  - Table 13. Miscellaneous Signals (Signals that Are Not Data, Address, or Strobe)71
  - Topologies72
- Figure 48. THERMTRIP# Power down Sequence82
- Figure 49. Voltage Divider Network for Reference Voltage Generation82
- Intel ® MCH System Bus Interface82
- Figure 50. Pull-Down Circuit83
- Intel ® MCH System Bus I/O Decoupling Requirements83
- System Bus Routing Guidelines - Four-Layer Motherboard85
Memory Interface Routing89
- Rambus RDRAM* Device Routing Guidelines90
- Rambus Technology Routing Guidelines - Four-Layer Motherboard110
AGP Interface Routing113
- Table 25. AGP 2.0 Signal Groups113
- AGP Routing Guidelines114
- AGP Universal Retention Mechanism (RM)121
- Table 28. 3.3 V and 5 V Tolerant Signals During 1.5 V Operation121
- Figure 78. AGP Left Handed Retention Mechanism Drawing122
- Figure 79. AGP Left Handed Retention Mechanism Keep-Out Information123
- Table 29 List of Vendors for Retention Mechanism123
- AGP Routing Guidelines - Four-Layer Motherboard124
- Figure 80. Example AGP Routing (Top Layer)124
- Figure 81. Example AGP Routing (Bottom Layer)125
- Figure 82. Example VDDQ Plane on Layer 2126
Hub Interface Routing127
- Hub Interface Routing Guidelines127
- Figure 83. 8-Bit Hub Interface Routing Example127
- 8-Bit Hub Interface Routing Guidelines128
- Hub Interface Routing Guidelines - Four-Layer Motherboard131
- Figure 86. Example Hub Interface Breakout / 1.8 V MCH Fingers131
I/O Controller Hub 2133
- This Chapter Provides Information on the Intel 82801BA I/O Controller Hub 2 (ICH2) IDE Interface133
  - IDE Cable133
  - Cable Detection for Ultra ATA/66 and Ultra ATA/100134
  - Primary IDE Connector Requirements137
  - Figure 89. Connection Requirements for Primary IDE Connector137
  - Secondary IDE Connector Requirements138
  - Figure 90. Connection Requirements for Secondary IDE Connector138
- Communication and Networking Riser (CNR)139
  - CNR Placement139
  - Figure 91. CNR Interface139
- Intel ® AC'97140
  - Figure 92. Intel ® ICH2 AC'97 - Codec Connection140
  - Table 54. Intel140
  - Table 55. Intel140
  - Figure 93. Audio Codec141
  - Figure 94. Modem Codec141
  - Figure 95. Audio/Modem Codec141
  - Figure 96. Modem Codecs142
  - Figure 97. Audio and Modem Codecs142
  - Figure 98. Audio Codecs143
  - Figure 99. Audio and Audio/Modem Codecs143
  - AC'97 Audio Codec Detect Circuit and Configuration Options144
  - Table 33. Intel ® AC'97 SDIN Pull-Down Resistors144
  - Figure 100. CDC_DN_ENAB# Support Circuitry for a Single Codec Motherboard145
  - Figure 101. CDC_DN_ENAB# Support Circuitry for Multi-Channel Audio Upgrade146
  - Figure 102. CDC_DN_ENAB# Support Circuitry for Two-Codecs on Motherboard / One-Codec on CNR146
  - Figure 103. CDC_DN_ENAB# Support for Two-Codecs on Motherboard / Two-Codecs on CNR147
  - Table 34. Signal Descriptions147
  - Valid Codec Configurations148
- USB Guidelines148
- Table 35. Codec Configurations148
- IOAPIC Design Recommendations149
- Figure 104. USB Data Signals149
- Smbus/Smlink Interface150
  - Figure 105. Smbus/Smlink Interface150
  - Smbus Architecture and Design Considerations151
- Pci153
  - Figure 108. Mixed Vcc_Suspend/Vcc_Core Architecture153
  - Figure 109. PCI Bus Layout Example153
  - Figure 110. Example PCI Power Planes on Layer 2154
  - PCI Routing - Four-Layer Motherboard154
  - Figure 111. Example PCI Routing on Layer 1155
  - Figure 112. Example PCI Routing on Layer 4156
- Rtc157
  - RTC Crystal157
  - Figure 113. External Circuitry for the Intel157
  - External Capacitors158
  - RTC Layout Considerations158
  - RTC External Battery Connection158
  - RTC External RTCRST Circuit159
  - Figure 114. Diode Circuit to Connect RTC External Battery159
  - RTC Routing Guidelines160
  - VBIAS DC Voltage and Noise Measurements160
  - Figure 115. RTCRST External Circuit for the Intel160
  - Power-Well Isolation Control161
  - Figure 116. RTC Power-Well Isolation Control161
  - Power Supply PS_ON Consideration162
- LAN Layout Guidelines162
  - Table 36. Integrated LAN Options162
  - Figure 117. Intel ® ICH2 / LAN Connect Section163
  - Table 37. LAN Design Guide Section Reference163
  - Intel ® ICH2 - LAN Interconnect Guidelines164
  - General LAN Routing Guidelines and Considerations167
  - Intel ® 82562EH Home/Pna* Guidelines172
  - Intel ® 82562ET / 82562EM Guidelines175
  - Figure 128. Intel ® 82562ET/EM Disable Circuit180
  - Intel ® 82562 ET/EM Disable Guidelines180
  - 82562ET / 82562EH Dual Footprint Guidelines181
  - Figure 129. Dual Footprint LAN Connect Interface181
  - Figure 130. Dual Footprint Analog Interface181
- Intel ® ICH2 Routing Guidelines - Four-Layer Motherboard183
- Figure 131. Example Intel ® ICH2 Top Layer Breakout Using Standard Size Vias183
- Figure 132. Example Intel ® ICH2 Bottom Layer Breakout Using Standard Size Vias184
- FWH Guidelines185
  - FWH Decoupling185
  - In Circuit FWH Programming185
  - FWH Vpp Design Guidelines185
  - Figure 133. FWH VPP Isolation Circuitry185
- Intel ® ICH2 Decoupling Recommendations186
- Glue Chip 4 (Intel ICH2 Glue Chip)186
- Table 42. Decoupling Capacitor Recommendation186
- SPKR Pin Consideration187
- Figure 134. SPKR Circuit187
- 1.8 V and 3.3 V Power Sequence Requirement188
- Figure 135. Example Power-On 3.3 V / 1.8 V Sequencing Circuit188
- PIRQ Routing189
- Figure 136. Example PCI IRQ Routing189
- Table 43. IOAPIC Interrupt Inputs 16 through 23 Usage189
Additional Design Considerations191
- Retention Mechanism Placement and Keepouts191
- Figure 137. RM Keepout Drawing 1192
- Figure 138. RM Keepout Drawing 2193
- Figure 139. Intel ® MCH Keepouts and RM Hole Locations194
- Power Header for Active Cooling Solutions195
- Table 44. Reference Solution Fan Power Header Pinout195
- Table 45. Boxed Processor Fan Power Header Pinout195
- Intel ® Pentium197
  - Intel® Pentium® 4 Processor in the 478-Pin Package Processor Power Distribution Guidelines197
- Power Requirements197
- Thermal Considerations220
- Simulation223
- Filter Specifications for VCCA, VCCIOPLL, and VSSA225
- Figure 168. Typical VCCIOPLL, VCCA and VSSA Power Distribution225
- Figure 169. Filter Recommendation226
- Figure 170. Example Component Placement for PLL Filter227
Power Distribution Guidelines229
- Definitions229
- Power Management229
- 1.8 V RAC Isolation Solution231
- Figure 172. Inductor-Capacitor Filter Circuit231
- Figure 173. Ferrite Bead Filter Circuit232
- Figure 174. Customer Reference Board Layout Example233
- Figure 175. Customer Reference Board Layout Example (Bottom - Layer 6)233
- Vterm/VDD Power Sequencing Requirement234
- Figure 176. Customer Reference Board Layout Example (Signal 2 - Layer 4)234
- Figure 177. 1.8 V and 2.5 V Power Sequence (Schottky Diode)234
- Intel ® 850 Chipset Power Sequencing Requirements235
- Figure 178. Desired Mode of Power Sequencing235
- Figure 179. Optional Mode of Power Sequencing235
- Intel ® ICH2 V5REF and Vcc3.3 Sequencing Requirement236
- Figure 180. V5REF Sequencing Circuit236
- CPU / CK00 Power Sequencing Requirement237
- Figure 181. CPU/CK00 Sequencing Circuit237
Debug Port Routing Guidelines239
Debug Tools Specifications241
- Logic Analyzer Interface (LAI)241
  - Mechanical Considerations241
  - Electrical Considerations241
Schematic Review Checklist243
- Processor Checklist (All Signals)243
- CK00 Clock Generator Checklist248
- Direct Rambus Clock Generator (DRCG1 and DRCG2) Checklist249
- Intel ® 850 Chipset Checklist251
- AGP Checklist253
- Rambus RIMM* Connector Checklist255
- Intel ® ICH2 Checklist259
Layout Review Checklist269
- Processor and System Bus269
- CK00 Routing Guidelines274
  - CK00 Clocking274
- RAMBUS Technology Routing Guidelines276
- AGP Guidelines282
- Bit Hub Interface285
  - Hub Decoupling285
- IDE Interface286
- Cnr286
- Intel ® AC'97286
- Usb287
- Intel ® ICH2 Decoupling287
- Rtc288
- LAN* Connect Interface288
- Miscellaneous289
Appendix A: Reference Schematics291

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