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Ultra ATA/66, 2.13.1 Ultra ATA/66 Detection - motherboard bios

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Layout/Routing Guidelines 2.13 2.13.1 Ultra ATA/66 This section contains guidelines for connecting and routing the ICH IDE interface. The ICH has two independent IDE channels. This section provides guidelines for IDE connector cabling and motherboard design, including component and resistor placement, and signal termination for both IDE channels. The ICH has integrated the 33 Ω series resistors that have been typically required on the IDE data signals running to the two ATA connectors. The IDE interface can be routed with 5 mil traces on 5 mil spaces, and must be less than 8 inches long (from ICH to IDE connector). Additionally, the shortest IDE signal (on a given IDE channel) must be less than 0.5" shorter than the longest IDE signal (on that channel). Cable • Length of cable: Each IDE cable must be equal to or less than 18 inches. • Capacitance: Less than 30 pF. • Placement: A maximum of 6 inches between drive connectors on the cable. If a single drive is placed on the cable it should be placed at the end of the cable. If a second drive is placed on the same cable it should be placed on the next closest connector to the end of the cable (6" away from the end of the cable). • Grounding: Provide a direct low impedance chassis path between the motherboard ground and hard disk drives. • ICH Placement: The ICH must be placed equal to or less than 8 inches from the ATA connector(s). • PC99 requirement: Support Cable Select for master-slave configuration is a system design requirement for Microsoft* PC99. CSEL signal needs to be pulled down at the host side by using a 470 Ω pull-down resistor for each ATA connector. Ultra ATA/66 Detection The Intel® 820 chipset supports many Ultra DMA modes including ATA/66. The Intel® 820 chipset needs to determine the installed IDE device mode and the type of cable to configure its own hardware and software to support it. A new IDE cable is required for Ultra ATA/66. This cable is an 80 conductor cable; however the 40 pin connectors do not change. The wires in the cable alternate: ground, signal, ground, signal, ground, signal, ground... All the ground wires are tied together on the cable (and they are tied to the ground on the motherboard through the ground pins in the 40 pin connector). This cable conforms to the Small Form Factor Specification SFF-8049. This specification can be obtained from the Small Form Factor Committee. To determine if ATA/66 mode can be enabled, the Intel® 820 chipset requires the system BIOS to attempt to determine the cable type used in the system. The BIOS does this in one of two ways: • Host Side Detection • Device Side Detection If the BIOS detects an 80-conductor cable, it may use any Ultra DMA mode up to the highest transfer mode supported by both the Intel® 820 chipset and the IDE device. Otherwise, the BIOS can only enable modes that do not require an 80-conductor cable (e.g., Ultra ATA/33 Mode). After determining the Ultra DMA mode to be used, the BIOS will configure the Intel® 820 chipset hardware and software to match the selected mode. 2-56 Intel®820 Chipset Design Guide

Section	Page
Introduction 1	13
1.1 About This Design Guide	13
1.2 References	14
1.3 System Overview	14
1.3.1 Chipset Components	15
1.3.2 Bandwidth Summary	16
1.3.3 System Configuration	17
1.4 Platform Initiatives	20
1.4.1 Direct Rambus*	20
1.4.2 Streaming SIMD Extensions	20
1.4.3 AGP 2.0	20
1.4.4 Hub Interface	20
1.4.5 Manageability	21
1.4.6 AC’97	22
1.4.7 Low Pin Count (LPC) Interface	23
Layout/Routing Guidelines 2	27
2.1 General Recommendations	27
2.2 Component Quadrant Layout	27
2.3 Intel® 820 Chipset Component Placement	29
2.4 Core Chipset Routing Recommendations	30
2.5 Source Synchronous Strobing	31
2.6 Direct Rambus* Interface	33
2.6.1 Stackup	34
2.6.2 Direct Rambus* Layout Guidelines	34
2.6.2.1 RSL Routing	34
2.6.2.2 RSL Termination	37
2.6.2.3 Direct Rambus* Ground Plane Reference	39
2.6.2.4 Direct Rambus* Connector Compensation	40
2.6.2.5 RSL Signal Layer Alternation	46
2.6.2.6 Length Matching Methods	47
2.6.2.7 VIA Compensation	49
2.6.2.8 Length Matching & Via Compensation Example	49
2.6.3 Direct Rambus* Reference Voltage	51
2.6.4 High-speed CMOS Routing	51
2.6.4.1 SIO Routing	52
2.6.4.2 Suspend-to-RAM Shunt Transistor	52
2.6.5 Direct Rambus* Clock Routing	54
2.6.6 Direct Rambus* Design Checklist	54
2.7 AGP 2.0	57
2.7.1 AGP Interface Signal Groups	58
2.7.2 1X Timing Domain Routing Guidelines	59
2.7.3 2X/4X Timing Domain Routing Guidelines	59
2.7.4 AGP 2.0 Routing Summary	61
2.7.5 AGP Clock Routing	62
2.7.6 General AGP Routing Guidelines	62
2.7.7 VDDQ Generation and TYPEDET#	63
2.7.8 VREF Generation for AGP 2.0 (2X and 4X)	65
2.7.9 Compensation	67
2.7.10 AGP Pull-ups	67
2.7.10.1 AGP Signal Voltage Tolerance List	68
2.7.11 Motherboard / Add-in Card Interoperability	68
2.8 Hub Interface	69
2.8.1 Data Signals	70
2.8.2 Strobe Signals	70
2.8.3 HREF Generation/Distribution	70
2.8.4 Compensation	71
2.9 System Bus Design	72
2.9.1 100/133 MHz System Bus	72
2.9.2 System Bus Ground Plane Reference	73
2.10 S.E.C.C. 2 Grounding Retention Mechanism (GRM)	73
2.11 Processor CMOS Pullup Values	75
2.12 Additional Host Bus Guidelines	78
2.13 Ultra ATA/66	82
2.13.1 Ultra ATA/66 Detection	82
2.13.2 Ultra ATA/66 Cable Detection	83
2.13.3 Ultra ATA/66 Pullup/Pulldown Requirements	86
2.14 AC’97	87
2.14.1 AC’97 Signal Quality Requirements	89
2.14.2 AC’97 Motherboard Implementation	89
2.15 USB	91
2.16 ISA (82380AB)	92
2.16.1 ICH GPIO connected to 82380AB	92
2.16.2 Sub Class Code	92
2.17 IOAPIC Design Recommendation	92
2.18 SMBus/Alert Bus	93
2.19 PCI	93
2.20 RTC	93
2.20.1 RTC Crystal	94
2.20.2 External Capacitors	94
2.20.3 RTC Layout Considerations	95
2.20.4 RTC External Battery Connection	95
2.20.5 RTC External RTCRST Circuit	96
2.20.6 RTC Routing Guidelines	96
2.20.7 VBIAS DC Voltage and Noise Measurements	97
Advanced System Bus Design 3	101
3.1 Terminology and Definitions	101
3.2 AGTL+ Design Guidelines	104
3.2.1 Initial Timing Analysis	105
3.2.2 Determine General Topology, Layout, and Routing Desired	108
3.2.3 Pre-Layout Simulation	108
3.2.3.1 Methodology	108
3.2.3.2 Sensitivity Analysis	108
3.2.3.3 Monte Carlo Analysis	109
3.2.3.4 Simulation Criteria	109
3.2.4 Place and Route Board	110
3.2.4.1 Estimate Component To Component Spacing for AGTL+ Signals	110
3.2.4.2 Layout and Route Board	110
3.2.4.3 Host Clock Routing	112
3.2.4.4 APIC Data Bus Routing	112
3.2.5 Post-Layout Simulation	113
3.2.5.1 Intersymbol Interference	113
3.2.5.2 Cross-Talk Analysis	113
3.2.5.3 Monte Carlo Analysis	113
3.2.6 Validation	114
3.2.6.1 Measurements	114
3.2.6.2 Flight Time Simulation	114
3.2.6.3 Flight Time Hardware Validation	115
3.3 Theory	115
3.3.1 AGTL+	115
3.3.2 Timing Requirements	116
3.3.3 Cross-talk Theory	116
3.3.3.1 Potential Termination Cross-Talk Problems	118
3.4 More Details and Insight	119
3.4.1 Textbook Timing Equations	119
3.4.2 Effective Impedance and Tolerance/Variation	120
3.4.3 Power/Reference Planes, PCB Stackup, and High Frequency Decoupling	120
3.4.3.1 Power Distribution	120
3.4.3.2 Reference Planes and PCB Stackup	121
3.4.3.3 High Frequency Decoupling	122
3.4.3.4 SC242 Connector	123
3.4.4 Clock Routing	123
3.5 Definitions of Flight Time Measurements/ Corrections and Signal Quality	124
3.5.1 VREF Guardband	124
3.5.2 Ringback Levels	124
3.5.3 Overdrive Region	124
3.5.4 Flight Time Definition and Measurement	125
3.6 Conclusion	126
Clocking 4	129
4.1 Clock Generation	129
4.2 Component Placement and Interconnection Layout Requirements	134
4.2.1 14.318MHz Crystal to CK133	134
4.2.2 CK133 to DRCG	134
4.2.3 MCH to DRCG	135
4.2.4 DRCG to RDRAM Channel	136
4.2.5 Trace Length	136
4.3 DRCG Impedance Matching Circuit	138
4.3.1 DRCG Layout Example	139
4.4 AGP Clock Routing Guidelines	139
4.5 Series Termination Resistors for CK133 Clock Outputs	139
4.6 Unused Outputs	140
4.7 Decoupling Recommendation for CK133 and DRCG	140
4.8 DRCG Frequency Selection and the DRCG+	140
4.8.1 DRCG Frequency Selection Table and Jitter Specification	140
4.8.2 DRCG+ Frequency Selection Schematic	141
System Manufacturing 5	145
5.1 In Circuit FWH Flash BIOS Programming	145
5.2 FWH Flash BIOS Vpp Design Guidelines	145
5.3 Stackup Requirement	145
5.3.1 Overview	145
5.3.2 PCB Materials	146
5.3.3 Design Process	146
5.3.4 Test Coupon Design Guidelines	147
5.3.5 Recommended Stackup	147
5.3.6 Inner Layer Routing	147
5.3.7 Impedance Calculation Tools	148
5.3.8 Testing Board Impedance	148
5.3.9 Board Impedance/Stackup Summary	149
System Design Considerations 6	153
6.1 Power Delivery	153
6.1.1 Terminology and Definitions	153
6.1.2 Intel® 820 Chipset Customer Reference Board Power Delivery	154
6.1.3 64/72Mbit RDRAM Excessive Power Consumption	157
6.1.3.1 Option 1: Reduce the Clock Frequency During Initialization	158
6.1.3.2 Option 2: Increase the Current Capability of the 2.5V Voltage Regulator	158
6.2 Power Plane Splits	159
6.3 Thermal Design Power	159
6.4 Glue Chip 3 (Intel® 820 Chipset Glue Chip)	160
Appendix A: Reference Board Schematics: Uni-Processor	161
Reference Design Schematics: Uni-Processor A	163
Appendix B: Reference Design Schematics: Dual-Processor B	201

Match case Limit results 1 per page

Layout/Routing Guidelines

2-56

Intel

820 Chipset

Design Guide

2.13

Ultra ATA/66

This section contains guidelines for connecting and routing the ICH IDE interface. The ICH has

two independent IDE channels. This section provides guidelines for IDE connector cabling and

motherboard design, including component and resistor placement, and signal termination for both

IDE channels. The ICH has integrated the 33

Ω

series resistors that have been typically required on

the IDE data signals running to the two ATA connectors.

The IDE interface can be routed with 5 mil traces on 5 mil spaces, and must be less than 8 inches

long (from ICH to IDE connector). Additionally, the shortest IDE signal (on a given IDE channel)

must be less than 0.5” shorter than the longest IDE signal (on that channel).

Cable

•

Length of cable:

Each IDE cable must be equal to or less than 18 inches.

•

Capacitance:

Less than 30 pF.

•

Placement:

A maximum of 6 inches between drive connectors on the cable. If a single drive is

placed on the cable it should be placed at the end of the cable. If a second drive is placed on the

same cable it should be placed on the next closest connector to the end of the cable (6” away

from the end of the cable).

•

Grounding:

Provide a direct low impedance chassis path between the motherboard ground

and hard disk drives.

•

ICH Placement:

The ICH must be placed equal to or less than 8 inches from the ATA

connector(s).

•

PC99 requirement:

Support Cable Select for master-slave configuration is a system design

requirement for Microsoft* PC99. CSEL signal needs to be pulled down at the host side by

using a 470

Ω

pull-down resistor for each ATA connector.

2.13.1

Ultra ATA/66 Detection

The Intel

820 chipset supports many Ultra DMA modes including ATA/66. The Intel

820

chipset needs to determine the installed IDE device mode and the type of cable to configure its own

hardware and software to support it.

A new IDE cable is required for Ultra ATA/66. This cable is an 80 conductor cable; however the 40

pin connectors do not change. The wires in the cable alternate: ground, signal, ground, signal,

ground, signal, ground… All the ground wires are tied together on the cable (and they are tied to

the ground on the motherboard through the ground pins in the 40 pin connector). This cable

conforms to the Small Form Factor Specification SFF-8049. This specification can be obtained

from the Small Form Factor Committee.

To determine if ATA/66 mode can be enabled, the Intel

820 chipset requires the system BIOS to

attempt to determine the cable type used in the system. The BIOS does this in one of two ways:

•

Host Side Detection

•

Device Side Detection

If the BIOS detects an 80-conductor cable, it may use any Ultra DMA mode up to the highest

transfer mode supported by both the Intel

820 chipset and the IDE device. Otherwise, the BIOS

can only enable modes that do not require an 80-conductor cable (e.g., Ultra ATA/33 Mode).

After determining the Ultra DMA mode to be used, the BIOS will configure the Intel

820 chipset

hardware and software to match the selected mode.