Design Guide 3
Contents
1 Overview ........................................................................................................ 6
1.1 Related Documents ............................................................................... 6
2 Motherboard Electrical Design Suggestions .......................................................... 7
2.1 PCI Bus ................................................................................................ 7
2.1.1 PCI Simulation ......................................................................... 7
2.1.2 Simulation Results and Recommendations ................................... 7
2.1.3 PCI REQ#/GNT# Implementation ............................................... 7
2.1.4 64-bit PCI ............................................................................... 8
2.1.5 IDSEL Assignment .................................................................... 8
2.1.6 3VSB ...................................................................................... 9
2.1.7 PCI_PME# ............................................................................... 9
2.2 IDE Signals .......................................................................................... 9
2.3 Floppy Signals ..................................................................................... 10
2.4 Power Signals ..................................................................................... 11
2.4.1 -5V ...................................................................................... 11
2.4.2 PWR_OK ............................................................................... 11
2.4.3 PS_ON# ............................................................................... 12
2.4.4 5VSB .................................................................................... 12
2.4.5 Power Design ........................................................................ 12
2.5 Front Panel Signals .............................................................................. 12
2.5.1 HD_PWR, HDA#, LED_GRN, and LED_YEL Signals ....................... 13
2.5.2 FPBUT_IN ............................................................................. 13
2.5.3 FPSLP# ................................................................................. 13
2.5.4 FP_RST# .............................................................................. 13
2.5.5 IRRX, IRTX, and IR_PWR Infrared Signals .................................. 14
2.6 Fan Control ......................................................................................... 14
2.7 Tamper Detection ................................................................................ 14
2.7.1 Tamper Detect Design ............................................................ 15
2.8 Implementing Audio on microATX Platforms ............................................. 15
2.9 Infrared Design ................................................................................... 16
2.10 Modem Wake ...................................................................................... 17
3 Motherboard Device Placement ........................................................................ 18
3.1 AGP-up Design .................................................................................... 18
3.2 AGP-down Design ................................................................................ 19
3.2.1 Motherboard Design Checklist ................................................... 20
4 Electrical Implementation of AGP ...................................................................... 23
4.1 Simulation Results ............................................................................... 23
5 Definitions .................................................................................................... 25
Figures
Figure 2-1. Motherboard Layout for Simulation Exercise ........................................ 8
Figure 2-2. Fan Control Circuitry ...................................................................... 14
Figure 2-3. Routing Audio, Example .................................................................. 15
Figure 2-4. Plane Splits, Example ..................................................................... 16
Figure 2-5. IR Implementation, Example ........................................................... 17
Figure 3-1. AGP-up Motherboard Layout, Example .............................................. 18
Figure 3-2. AGP-down Motherboard Layout, Example .......................................... 19
