Intel 41210 User Manual

Intel® 41210 Serial to Parallel PCI Bridge

Design Guide
May 2005
Order Number: 278801-004
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ii Intel® 41210 Serial to Parallel PCI Bridge Design Guide

Contents

Contents
1 About This Document ...................................................................................................................7
1.1 Terminology and Definitions .................................................................................................7
2 Introduction....................................................................................................................................9
2.1 PCI Express Interface Features............................................................................................9
2.2 PCI-X Interface Features......................................................................................................9
2.3 Power Management............................................................................................................10
2.4 SMBus Interface .................................................................................................................10
2.4.1 SMBus for configuration register initialization........................................................10
2.4.2 Microcontroller Connections to the 41210 Bridge..................................................11
2.5 JTAG...................................................................................................................................12
2.6 Related Documents ............................................................................................................12
2.7 Intel
3 Package Information ...................................................................................................................15
3.1 Package Specification ........................................................................................................15
4 Power Plane Layout ....................................................................................................................19
4.1 41210 Bridge Decoupling Guidelines .................................................................................19
4.2 Split Voltage Planes............................................................................................................21
®
41210 Serial to Parallel PCI Bridge Applications......................................................13
5 41210 Bridge Reset and Power Timing Considerations ..........................................................23
5.1 A_RST#,B_RST# and PERST# Timing Requirements ......................................................23
5.2 VCC15 and VCC33 Voltage Requirements........................................................................23
6 General Routing Guidelines .......................................................................................................25
6.1 General Routing Guidelines................................................................................................25
6.2 Crosstalk.............................................................................................................................25
6.3 EMI Considerations ............................................................................................................26
6.4 Power Distribution and Decoupling.....................................................................................27
6.4.1 Decoupling.............................................................................................................27
6.5 Trace Impedance................................................................................................................27
6.5.1 Differential Impedance...........................................................................................28
7 Board Layout Guidelines............................................................................................................29
7.1 Adapter Card Topology.. ....... ...... ....... ...... ....... ...... ...... ....... ...... ....... ....................................29
8 PCI-X Layout Guidelines.............................................................................................................31
8.1 Interrupts.............................................................................................................................31
8.1.1 Interrupt Routing for Devices Behind a Bridge.......................................................32
8.2 PCI Arbitration ....................................................................................................................32
8.2.1 PCI Resistor Compensation ..................................................................................33
8.3 PCI General Layout Guidelines ..........................................................................................33
8.3.1 PCI Pullup Resistors Not Required........................................................................34
8.4 PCI Clock Layout Guidelines ..............................................................................................35
8.5 PCI-X Topology Layout Guidelines.....................................................................................38
8.6 Intel
®
41210 Serial to Parallel PCI Bridge Design Guide Layout Analysis .........................38
Intel® 41210 Serial to Parallel PCI Bridge Design Guide iii
Contents
8.6.1 Embedded PCI-X 133 MHz ...................................................................................39
8.6.2 Embedded PCI-X 100 MHz ...................................................................................40
8.6.3 PCI-X 66 MHz Embedded Topology......................................................................41
8.6.4 PCI 66 MHz Embedded Topology.........................................................................42
8.6.5 PCI 33 MHz Embedded Mode Topology...............................................................43
9 PCI Express Layout.....................................................................................................................45
9.1 General recommendations ................................ ...... ...... ....... ...... ....... ...... ....... ...... ..............45
9.2 PCI-Express Layout Guidelines..........................................................................................46
9.3 Adapter Card Layout Guidelines.........................................................................................46
10 Circuit Implementations..............................................................................................................49
10.1 41210 Bridge Analog Voltage Filters..................................................................................49
10.1.1 PCI Analog Voltage Filters.....................................................................................50
10.1.2 PCI Express Analog Voltage Filter ........................................................................50
10.1.3 Bandgap Analog Voltage Filter..............................................................................51
10.2 Intel® 41210 Serial to Parallel PCI Bridge Reference and Compensation Pins.................53
10.2.1 SM Bus..................................................................................................................54
11 41210 Bridge Customer Reference Boards...............................................................................55
11.1 Board Stack-up..................................................................... ...... ....... ...... ....... ...... ....... .......55
11.2 Material...............................................................................................................................56
11.3 Impedance..........................................................................................................................56
11.4 Board Outline.................... ....... ...... ....... ...... ....... ...... ...... ....... ...... ........................................57
12 Design Guide Checklist ..............................................................................................................59
Figures
1 41210 Bridge Microcontroller Block Diagram .............................................................................11
2 41210 Bridge Microcontroller Connections.................................................................................11
3 41210 Bridge Block Diagram......................................................................................................12
4Intel
5 Top View - 41210 Bridge 567-Ball FCBGA Package Dimensions..............................................15
6 Bottom View - 41210 Bridge 567-Ball FCBGA Package Dimensions ........................................16
7 Side View - 41210 Bridge 567-Ball FCBGA Package Dimensions.............................................17
8 Decoupling Placement for Core and PCI Express Voltage Planes ............................................19
9 Decoupling Placement for PCI/PCI-X 1.5V and 3.3V Voltage Planes........................................20
10 41210 Bridge Single-Layer Split Voltage Plane..........................................................................22
11 Crosstalk Effects on Trace Distance and Height........................................................................26
12 PCB Ground Layout Around Connectors ...................................................................................26
13 Cross Section of Differential Trace.............................................................................................28
14 Two-by-two Differential Impedance Matrix .................................................................................28
15 Adapter Card Stackup .............. ....... ...... ....... ...... ....... ...... ...... ....... ...... ....... ...... ...........................30
16 PCI RCOMP ...............................................................................................................................33
17 PCI Clock Distribution and Matching Requirements...................................................................36
18 Embedded PCI-X 133 MHz Topology ........................................................................................39
19 Embedded PCI-X 100 MHz Topology ........................................................................................40
20 PCI-X 66 MHz Embedded Routing Topology.............................................................................41
21 PCI 66 MHz Embedded Topology..............................................................................................42
®
41210 Bridge Adapter Card Block Diagram......................................................................13
iv Intel® 41210 Serial to Parallel PCI Bridge Design Guide
Contents
22 PCI 33 MHz Embedded Mode Routing Topology.......................................................................43
23 PCI Analog Voltage Filter Circuit................................................................................................50
24 PCI Express Analog Voltage Filter Circuit ..................................................................................51
25 Bandgap Analog Voltage Filter Circuit........................................................................................52
26 Reference and Compensation Circuit Implementations .............................................................53
27 Proposed Mechanical Outline of the 41210 Bridge ....................................................................57
Tables
1 Terminology and Definitions.........................................................................................................7
2 41210 Bridge Decoupling Guidelines .........................................................................................21
3 Adapter Card Stack Up, Microstrip and Stripline ........................................................................29
4 INTx Routing Table.....................................................................................................................31
5 Interrupt Binding for Devices Behind a Bridge...........................................................................32
6 PCI-X Signals .............................................................................................................................34
7 PCI/PCI-X Frequency/Mode Straps............................................................................................34
8 PCI-X Clock Layout Requirements Summary.............................................................................37
9 PCI-X Slot Guidelines.................................................................................................................38
10 Embedded PCI-X 133 MHz Routing Recommendations............................................................39
11 Embedded PCI-X 100 MHz Routing Recommendations............................................................40
12 PCI-X 66 MHz Embedded Routing Recommendations..............................................................41
13 PCI 66 MHz Embedded Table....................................................................................................42
14 PCI 33 MHz Embedded Routing Recommendations..................................................................43
15 Adapter Card Routing Recommendations..................................................................................46
16 Recommended R, L and C Values for 41210 Bridge Analog Filter Circuits ...............................49
17 SMBUs Address Configuration...................................................................................................54
18 CRB Board Stackup....................................................................................................................56
19 PCI Express Interface Signals....................................................................................................59
20 PCI/PCI-X Interface Signals .......................................................................................................60
21 Miscellaneous Signals ................................................................................................................62
22 SMBus Interface Signals ............................................................................................................62
23 Power and Ground Signals.........................................................................................................63
24 JTAG Signals......................... ....... ...... ....... ...... ....................................... ...... ....... ...... .................64

Revision History

Date Revision Description
Removed Section 5.3, VCCPE and REFCLKn/REFCLKp
May 2005 004
October 2004 003
July 2004 002 Updated Chapters 4, 5, and 12
October 2003 001
July 2003 000 First internal draft of this document.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide v
Information Added signals to Section 8.3.1 Updated Table 19, Table 20, and Table 21
Updated PCI Express operation information in Section 2.1 and Table 19.
Added signal NC17 information in Table 21.
Updated content; second draft of this document; initial public release of this document.
Contents
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vi Intel® 41210 Serial to Parallel PCI Bridge Design Guide

About This Document 1

This document provides layout i nformation and guide lines for designing p latform or add-in board applications with the Intel
®
41210 Serial to Parall el PCI Br idge (also c alled the 41 210 Bridge). I t is recommended that this document be used as a guideline. Intel r ecommen ds emp l oyi ng b est -k now n design practices with board level simulation, signal integrity testing and validation for a robust design.
Designers should note that this guide focuses upon specific design considerations for the 41210 Bridge and is not intended to be an all-inclusive list of all good design practices. Use this guide as a starting point and use empirical data to optimize your particular design.

1.1 Terminology and Definitions

Table 1 provides a list of terms and definitions that may be useful when working with the 41210
Bridge product.
Table 1. Terminology and Definitions (Sheet 1 of 2)
Term Definition
Stripline
Stripline in a PCB is composed of the conductor inserted in a dielectric with GND planes to the top and bottom.
NOTE: An easy way to distinguish stripline
from microstrip is that you need to strip away layers of the board to view the trace on stripline.
Microstrip
Prepreg
Core
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 7
Material used for the lamination process of manufacturing PCBs. It consists of a layer of epoxy material that is placed between two cores. This layer melts into epoxy when heated and forms around adjacent traces.
Material used for the lamination process of manufacturing PCBs. This material is two sided laminate with copper on each side. The core is an internal layer that is etched.
Microstrip in a PCB is composed of the conductor on the top layer above the dielectric with a ground plane below
About This Document
Table 1. Terminology and Definitions (Sheet 2 of 2)
Term Definition
Layer 1: copper
Prepreg Layer 2: GND
Core
PCB
Example of a Four-Layer Stack
SSTL_2 Series Stub Terminated Logic for 2.5 V
JEDEC Provides standards for the semiconductor industry.
A network that transmits a coupled signal to another network is aggressor network.
Aggressor
Victim A network that receives a coupled cross-talk signal from another network is a victim network.
Network The trace of a PCB that completes an electrical connection between two or more components.
Stub Branch from a trunk terminating at the pad of an agent. CRB Customer Reference Board
Downstream
Upstream
Local memory
DWORD 32-bit data word.
Flip Chip
Mode
Conversion
PCI-E PCI-Express
Downstream refers either to the relative position of an interconnect/system element (Link/ device) as something that is farther from the Root Complex, or to a direction of information flow, i.e., when information is flowing away from the Root Complex.
Memory subsystem on the Intel XScale busses.
FC-BGA (flip chip-ball grid array) chip packages are designed with processor core flipped up on the back of the chip, facing away from the PCB. This allows more efficient cooling of the package.
Mode Conversions are due to imperfections on the interconnect which transform differential mode voltage to common mode voltage and common mode voltage to differential voltage.
Zo
Layer 3: VCC15 Prepreg Layer 4: copper
Zo
Victim Network
Aggressor Network
Printed circuit board. Example manufacturing process consists of
the following steps:
• Consists of alternating layers of core and prepreg stacked
• The finished PCB is heated and cured.
• The via holes are drilled
• Plating covers holes and outer surfaces
• Etching removes unwanted copper
• Board is tinned, coated with solder mask and silk screened
Zo
Zo
®
core DDR SDRAM or Peripheral Bus Interface
8 Intel® 41210 Serial to Parallel PCI Bridge Design Guide

Introduction 2

The Intel®41210 Serial to Parallel PCI Bridge integrates two PCI Express-to-PCI bridges. Each bridge follows the PCI-to-PCI Bridge programming model. The PCI Express port is compliant to the PCI Express Specification, Revision 1.0. The two PCI bus interfaces are fully compliant to the PCI Local Bus Specification, Revision 2.3.

2.1 PCI Express Interface Features

PCI Express Specification, Revision 1.0b compliant.
Support for single x8, single x4 or single x1 PCI Express operation.
64-bit addressing support.
32-bit CRC (cyclic redundancy checking) covering all transmitted data packets.
16-bit CRC on all link message information.
Raw bit-rate on the data pins of 2.5 Gbit/s, resulting in a raw bandwidth per pin of 250 MB/s.
Maximum realized bandwidth on PCI Express interface is 2 GB/s (in x8 mode) in each
direction simultaneously, for an aggregate of 4 GB/s .

2.2 PCI-X Interface Features

PCI Local Bus Specification, Revision 2.3 compliant.
PCI-to-PCI Bridge Specification, Revision 1.1 compliant.
PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0a compliant.
64-bit 66 MHz, 3.3 V, NOT 5 V tolerant.
On Die Termination (ODT) with 8.2K pull-up to 3.3V for PCI signals.
Six external REQ/GNT Pairs for internal arbiter on segment A and B respectively.
Programmable bus parking on either the last agent or always on Lanai.
2-level programmable round-robin internal arbiter with Multi-Transaction Timer (MTT)
External PCI clock-feed support for asynchronous primary and secondary domain operation.
64-bit addressing for upstream and downstream transactions
Downstream LOCK# support.
No upstream LOCK# support.
PCI fast Back-to-Back capable as target.
Up to four active and four pending upstream memory read transactions
Up to two downstream delayed (memory read, I/O read/write and configuration read/write)
transaction.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 9
Introduction
Tunable inbound read prefetch algorithm for PCI MRM/MRL commands
Local initialization via SMBus
Secondary side initialization via Type 0 configuration cycles.

2.3 Power Management

Support for PCI Express Active State Power Management (ASPM) L0s link state
Support for PCI PM 1.1 compatible D0, D3hot and D3cold device power states
Support for PME# event propagation on behalf of PCI devices

2.4 SMBus Interface

Compatible with System Management Bus Specification, Revision 2.0
Slave mode operation only.
Full read/write access to all configuration registers

2.4.1 SMBus for configuration register initialization

Support for local initialization of the configuration registers can be implemented using a
microcontroller via SMB. Figure 1shows this SMBus and the data transfer that occurs between the 41210 Bridge and the microcontroller.
Configuration Register information is stored internally in a microcontroller and the
information is transferred to the product via System Managed Bus (SMBus) protocols when the device receives power or reset.
The requirements of the microcontroller are as follows:
2
— Supports I — Has at least 256 Byte of internal EEprom space — To facilitate this programming on the Customer Reference Board a Microchip part
PIC16F876A was used.
— Code space: estimated code size is ~2K words of program space and 32 words of RAM
C and SMBus Prot ocols
10 Intel® 41210 Serial to Parallel PCI Bridge Design Guide
Figure 1. 41210 Bridge Microcontroller Block Diagram
SMBus 2.0
Introduction
Microcontroller
Configuration
Register
Data
Intelfi 41210 Bridge
Configuration
Register
Address Space

2.4.2 Microcontroller Connections to the 41210 Bridge

The following diagram shows the SMB interface from the 41210 Bridge to the microcontroller.
Figure 2. 41210 Bridge Microcontroller Connections
3.3 V
B2707-01
SDI / SDA SCK / SCL
RC1
RBO / INT
PIC16F876A
OSC2 / CLKOUT
20 MHz
OSC1 / CLKIN
22 pF 22 pF
B2708-01
Intelfi 41210 Bridge
CFGRETRY
CFG_RST_N
SMBDAT
SMBCLK
SMDAT
SMCLK
CFG_RETRY
CFG_RESET
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 11
Introduction

2.5 JTAG

Compliant with IEEE Standard Test Access Port and Boundary Scan Architecture 1149.1a

2.6 Related Documents

Intel® 41210 Serial to Parallel PCI Bridge Design Specification (EDS), Revision 1.0.
PCI Express Specification, Revision 1.0, from www.pci-sig.com.
PCI Express Design Guide, Revision 0.5
PCI Local Bus Specification, Revision 2.3, from www.pci-sig.com.
PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0a, from www.pci-sig.com.
IEEE Standard Test Access Port and Boundary Scan Architecture 1149.1a
System Management Bus Specification, Revision 2.0
Figure 3. 41210 Bridge Block Diagram
PCI-Express x8
JTAG SMB Bus
Intel
41210 Bridge
B_PCLKIA_PCLKI
A
Bus Arbiter
A
Clock Buffer
B
Bus Arbiter
B
Clock Buffer
A Bus PCI-X 133MHz
6 REQ/GNT Pairs
6 A_PCLKO
B Bus PCI-X 133MHz
6 REQ/GNT Pairs
6 B_PCLKO
B2709-01
12 Intel® 41210 Serial to Parallel PCI Bridge Design Guide

2.7 Intel®41210 Serial to Parallel PCI Bridge Applications

This section provides a block diagram for a typical the 41210 Bridge application. This application shows a PCI-E adapter card with two Dual 2Gb Fibre Channel controllers. Each of the PCI-X bus segments is connected to the Dual 2Gb Fibre Channel chip running at 133MHz. The two Dual FC chips provides the four 2Gb/s outputs.
Figure 4. Intel
®
41210 Bridge Adapter Card Block Diagram
Introduction
I2C Micro
Controller
®
41210
Intel
Bridge
PCI-X to
PCI Express
PCI Express
(to Server)
SFP Optical
Dual 2Gb
FC
133 MHz PCI-X
Dual 2Gb
FC
This is locally configurable from SMBus or PCI-X interfaces (no BIOS support or Drivers required)
SFP Optical
SFP Optical
SFP Optical
Module
Module
Module
Module
2 Gb/s
2 Gb/s
2 Gb/s
2 Gb/s
B1491-02
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 13
Introduction
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14 Intel® 41210 Serial to Parallel PCI Bridge Design Guide

Package Information 3

3.1 Package Specification

The 41210 Bridge is in a 567-ball FCBGA package, 31mm X 31mm in size, with a 1.27mm ball pitch.
Figure 5. Top View - 41210 Bridge 567-Ball FCBGA Package Dimensions
Han d lin g
Exclusion
Area
0.550 in.
0.550 in.
17.00 mm
21.00 mm
Die Area
17.00 mm
21.00 mm
31.00 mm
31.00 mm
Pkg_567-Ball_Top
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 15
Package Information
Figure 6. Bottom View - 41210 Bridge 567-Ball FCBGA Package Dimensions
AD AC
AB AA
Y
W
V
U
T
4X 0.635
4X 15.500
23X 1.270
R
P
N M
L K
J H G F E D
C B
+
+
A
4681012 1618202224214
3 5 7 9 11 13 15 211 231917
23X 1.270
8X 14.605
(0.895)
29.2100
31.00 – 0.100
A
0.200
-B-
31.00 – 0.100
-A-
B2711-01
16 Intel® 41210 Serial to Parallel PCI Bridge Design Guide
Figure 7. Side View - 41210 Bridge 567-Ball FCBGA Package Dimensions
Detail J
Underfill
Epoxy
Scale 5:1
FC BGA Substrate
Die
H
Detail H
Scale 5:1
1.170 – 0.085
0.600 – 0.100
J
Package Information
0.74 – 0.025
0.100 – 0.025
Die Solder Bumps
1.940 – 0.150 BGA Solder Balls
B2712-01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 17
Package Information
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18 Intel® 41210 Serial to Parallel PCI Bridge Design Guide

Power Plane Layout 4

This chapter provides detail s on the decoupling and voltage plan es needed to b ias the 41210 Br idge package.

4.1 41210 Bridge Decoupling Guidelines

Table 2 lists the decoupling guidelines for the 41210 Bridge. Figure 8 and Figure 9 provide the
decoupling capacitors around the 41210 Bridge ball grid pins.
Figure 8. Decoupling Placement for Core and PCI Express Voltage Planes
B2713-01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 19
Power Plane Layout
Figure 9. Decoupling Placement for PCI/PCI-X 1.5V and 3.3V Volt age Planes
Capacitor Legend
0603-0.1 F 0603-1 F
1206-10 F
B2714-01
20 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
T a ble 2. 41210 Bridge Decoupling Guidelines
Power Plane Layout
Vol tage Plane Voltage
PCI/PCI-X
Voltage
PCI/PCI-X
Voltage
PCI/PCI-X
Voltage
Core Voltage 1.5V VCC15 0.1 0603 200 2.0 5
Core Voltage 1.5V VCC15 1.0 0805 200 2.3 5
Core Voltage 1.5V VCC15 10 1206 200 1.9 2
PCI Express
Voltage
PCI Express
Voltage
PCI Express
Voltage
3.3V VCC33 0.1 0603
3.3V VCC33 1.0 0603
3.3V VCC33 10 1206
1.5V VCCPE 0.1 0603 200 2.0 3
1.5V VCCPE 1 0805 200 2.3 4
1.5V VCCPE 10 1206 200 1.9 2
41210
Pins
C
(uF)
Package
ESR
(mΩ)
50-
300
50-
300
50-
300
ESL (nH)
1.0-
3.0
1.0-
3.0
1.0-
3.0
Caps
# of
5
As close as design
2
41210 Bridge BGA As close as design
3
41210 Bridge BGA
As close as design 41210 Bridge BGA
As close as design 41210 Bridge BGA
As close as design 41210 Bridge BGA
As close as design 41210 Bridge BGA
Location
Beneath 41210
Bridge BGA
rules will allow to
rules will allow to
Beneath 41210
Bridge BGA
rules will allow to
rules will allow to
Beneath 41210
Bridge BGA
rules will allow to
rules will allow to

4.2 Split Voltage Planes

There are two 1.5V voltage planes that supply power to the 41210 Bridge:
VCC15:1.5V ±5% (1.5V core voltage)
VCCPE:1.5V ±3% (1.5V PCI Express voltage)
The 41210 Bridge core (VCC15), PCI-Express (VCCPE) voltages should be supplied by two separate voltage regulators or a single regulator. If VCC15 and VCCPE is supplied by a single voltage regulator the power planes should be split as shown in Figure 10.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 21
Power Plane Layout
Note: Linear voltage regulators are recommended when using 1.5 Volt power supplies.
Figure 10. 41210 Bridge Single-Layer Split Voltage Plane
re
Core
PCI
Express
B2715-01
22 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
41210 Bridge Reset and Power Timing
Considerations 5
This chapter describes the 41210 Bridge reset timing considerations.

5.1 A_RST#,B_RST# and PERST# Timing Requirements

The PCI-X Specification requires that there is a 100ms delay from valid power (PERST#) to reset deassertion (A_RST#/B_RST#). 41210 Bridge will keep A_R ST# /B_ RS T # asserted for a minimum of 320ms after PERST# is deasserted.

5.2 VCC15 and VCC33 Voltage Requirements

The following steps are the power sequencing requirements that must be followed with the 41210 Bridge:
1. The 41210 Bridge requires that the VCC33 voltage rail be no less than 0.5V below VCC15 (absolute voltage value) at all times during 41210 operation, including during system power up and power down. In other words, the following must always be true:
VCC33 >= (VCC15 – 0.5V) This can be accomplished by placing a diode (with a voltage drop <0.5V) between VCC15 and
VCC33. A node will be connected to VCC15 and cathode will be connected to VCC33. If VCC15 (1.5V PCI-X I/O voltage) and VCC15 (1.5V core voltage) are tied together on the
platform, then both voltages must meet the above rule.
Note: Linear voltage regulators are recommended when using 1.5 Volt power supplies.
2. If a voltage regulator solution is used which shunts VCC15 to ground while VCC33 is powered, the maximum all owa ble t ime that VCC15 can be shunted to ground whil e V C C33 is fully powered is 20ms.
3. The maximum allowed time between VCC33 and VCC15 ramping is 525ms .
Note: There is no minimum sequencing time requirement other thanrequirements in Steps 2 and 3.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 23
41210 Bridge Reset and Power Timing Considerations
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24 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

General Routing Guidelines 6

This chapter provides some basic ro uting guidel ines for layout and design of a printed circuit board using the 41210 Bridge. The high-speed clocking required when designing with the 41210 Bridge requires special attention to signal integrity. In fact, it is highly recommended that the board design be simulated to determine optimum layout for signal integrity. The information in this chapter provides guidelines to aid the designer with board layout. Several factors influence the signal integrity of a 41210 Bridge design. These factors include:
power distribution
minimizing crosstalk
decoupling
layout considerations when routing the PCI Express bus and PCI-X bus interfaces

6.1 General Routing Guidelines

This section details general routing guidelines for designing with the 41210 Bridge. The order in which signals are routed varies from desi gner to designer. Some designers prefer to route all clock signals first, while others prefer to route all high-speed bus signals first. Either order can be used, provided the guidelines listed here are followed.

6.2 Crosstalk

Crosstalk is caused by capacitive and inductive coupling between signals. Crosstalk is composed of both backward and forward cr osstalk comp onents. Back ward crosstalk cre ates an induced signal on victim network that propagates in the opposite direction of the aggressor signal. Forward crosstalk creates a signal that propagates in the same direction as the aggressor signal.
Circuit board analysis software is used to analyze your board layout for crosstalk problems. Examples of 2D analysis tools include Parasitic Parameters from ANSOFT
*
Design
software is not available, the layout should be designed to maintain at least the minimum recommended spacing for bus interfaces.
. Crosstalk problems occur when circuit etch lines run in parallel. When board analysis
A general guideline to use is, that space distance between adjacent signals be a least 3.3 times
the distance from signal trace to the nearest return plane. The coupled noise between adjacent traces decreases by the square of the distance between the adjacent traces.
It is also recommended to specify the height of the above reference plane when laying out
traces and provide this parameter to the PCB manufacturer. By moving traces closer to the nearest reference plane, the coupled noise decreases by the square of the distance to the reference plane.
*
and XFS from Quad
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 25
General Routing Guidelines
Figure 11. Crosstalk Effects on Tr ace Distance and Height
P
H
aggressor victim
Avoid slots in the ground plane. Slots increases mutual inductance thus increasing crosstalk.
Make sure that ground plane surrounding connector pin fields are not completely cleared out.
When this area is completely cleared out, around the connector pins, all the return current must flow together around the pin field increasing crosstalk. The preferred method of laying out a connector in the GND layer is shown in Figure 12.
Figure 12. PCB Ground Layout Around Connectors
Connector
Connector Pins
Reference Plane
Reduce Crosstalk:
- Maximize P
- Minimize H
A9259-01
GND PCB Layer
A. Incorrect method B. Correct method
A9260-01

6.3 EMI Considerations

It is highl y recommen ded that good EMI design practice s be followed when designing with th e 41210 Bridge.
To minimize EMI on your PCB a useful technique is to not extend the power planes to the
edge of the board.
Another technique is to surround the perimeter of your PCB layers with a GND trace. This
helps to shield the PCB with grounds minimizing radiation. The below link can provide some useful general EMI guidelines considerations:
http://developer.intel.com/design/auto/mcs96/applnots/272673.htm
26 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

6.4 Power Distribution and Decoupling

Have ample decoupling to ground, for the power planes, to minimize the effects of the switching currents. Three types of decoupling are: the bulk, the high-frequency ceramic, and the inter-plane capacitors.
Bulk capacitance consist of electrolytic or tantalum capacitors. These capacitors supply large
reservoirs of charge, but they are useful only at lower frequencies due to lead inductance effects. The bulk capacitors can be located anywhere on the board.
For fast switching currents, high-frequency low-inductance capacitors are most ef fective.
Place these capacitors as close to the device being decoupled as possible. This minimizes the parasitic resistance and inductance associated with board traces and vias.
Use an inter-plane capacitor between power and ground planes to reduce the effective plane
impedance at high frequencies. The general guideline for placing capacitors is to place high­frequency ceramic capacitors as close as possible to the module.

6.4.1 Decoupling

Inadequate high-frequency decoupling results in intermittent and unreliable behavior.
General Routing Guidelines
A general guideline recommends that you use the largest easily available capacitor in the lowest inductance package. For specific decoupling requirements for a 41210 Bridge application please refer to Chapter 4.

6.5 Trace Impedance

All signal layers require contr olled impeda nce 60 +/- 15%, microstrip or stripline f or add-in card applications. Selecting the appropriate board stack-up to minimi ze impedan ce variation s is very important. When calculating flight times, it is important to consider the minimum and maximum trace impedance based on the switching neighboring traces. Use wider s paces between traces, since this can minimize trace-to-trace coupling, and reduce cross talk.
When a different stack up is used the trace widths must be adjusted appropriately. When wider traces are used, the trace spacing must be adjusted accordingly (linearly).
It is highly recommended that a 2D Field Solver be used to design the high-speed traces. The following Impedance Calculator URL provide approximations for the trace impedance of various topologies. They may be used to generate the starting point for a full 2D Field solver.
http://emclab.umr.edu/pcbtlc/
The following website link provides a useful basic guideline for calculating trace parameters:
http://www.ultracad.com/calc.htm
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 27
General Routing Guidelines
Note: Using stripline transmission lines may give better results than m icrostri p. This is due to th e
difficulty of precisely controlling the dielectric constant of the solder mask, and the difficulty in limiting the plated thickness of microstrip conductors, which can substantially increase cross-talk.

6.5.1 Differential Impedance

The PCI Express standard defines a 100 differential impedance. This sect ion provides some basi c background information on the differential impedance calculations. In the cross section of
Figure 13 shows the cross section of two traces of a differential pair.
Figure 13. Cross Section of Different ial Trace
Ground reference plane
B2716 -01
To calculate the coupled impedance requires a 2x2 matrix. The diagonal values in the matrix represent the impedance of the traces to ground and the off-diagonal values provide a measure of how tightly the traces are coupled. The “differential impedance is the value of the line-to-line resistor terminator that optimally terminates pure differential signals.” The two by two matrix is shown below as:
Figure 14. Two-by-two Differential Impedance Matrix
Z11 Z12
=
Z
o
Z21 Z22
For a symmetric trace Z11 = Z22, the differential impedance can be calculated from this equation:
Z
differential
For two traces to be symmetric, they must have the same width, thickness and height above the ground plane.
= 2(Z11-Z12)
1
With the traces terminated with the appropriate differential, impedance ringing is
minimized.
B2717 -01
1. “Terminating Differential Signals on PCBs”, Steve Kaufer and Kelee Crisafulli, Printed Circuit Design, March 1999
28 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

Board Layout Guidelines 7

This chapter provides details on adapter card stackup suggestions. It is highly recommended that signal integrity simulations be run to verify each 4 121 0 B ridge PCB layout es pecially if it dev iates from the recommendations listed in these design guidelines.

7.1 Adapter Card Topology

The 41210 Bridge will be implemented on PCI-E adapter cards with an eight layer stackup PCB. The specified impedance range for all adapter card implementations will be 60 Adjustments will be made for interfaces specified at other impedances. Table 3 defines the typical layer geometries for eight layer boards.
T a ble 3. Adapter Card Stack Up, Microstrip and Stripline
+/-15%.
Variable Type
Solder Mask Thickness (mil) N/A 0.8 0.6 1.0
Solder Mask E
Core Thickness (mil) N/A 2.8 3.0 3.2
Core E
Plane Thickness (mil)
Trace Height
Trace Thickness (mil)
Trace Width (mil) Microstrip 4.0 2.5 5.5
Total Thickness (mil) FR4 62.0 56.0 68.0
(mil)
Preg E
N/A 3.65 3.65 3.65
r
N/A 4.3 3.75 4.85 2113 material
r
Power 2.7 2.5 2.9
Ground 1.35 1.15 1.55
13.53.33.7
23.53.33.7 3 10.5 9. 9 11.1
Microstrip 4.30 3.75 4.85 2113 material
Stripline1 4.30 3.75 4.85 2113 material
r
Stripline2 4.3 3.75 4.85
Microstrip 1.75 1.2 2.3
Stripline 1.4 1.2 1.6
Stripline 4.0 2.5 5.5
Nominal
(mils)
Minimum
(mils)
Maximum
(mils)
Notes
The trace height will be determined to achieve a nominal 60 Ω.
7628 material. Trace height 3 is composed of one piece of 2113 and one piece of
7628.
Trace Spacing (using
microstrip E2E/C2C)
Trace Spacing (using
stripline E2E/C2C) [12]/[16]
Trace Impedance
[12]/[16]
Microstrip 60 51 69
Stripline 60 51 69
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 29
Board Layout Guidelines
NOTE: Each interface will set the trace spacing based on its signal integrity of differential impedance
requirements. For the purposes of the building the transmission line models, it is assumed the artwork is very accurate and therefore a constant. Thus, all the variability in the trace spacing is the result of the tolerances of the trace width.
Figure 15. Adapter Card Stackup
L1
L3
Total Thicken ss
Microstrip
Trace
Spacing
L4
L2 (GND)
L4 (VCC)
L5 (VCC)
L7 (GND)
L8
Stripline
Trace
Spacing
Microstrip
Trace Width
L1
L3
Stripline
Trace Width
Microstrip Trace Thickness
Solder Mask Thickness
Trace Height 1 Trace Height 2
Stripline Trace Thickness
Trace Height 3
Core Thickness Plane Thickness
L4
B1436-01
30 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

PCI-X Layout Guidelines 8

This chapter describes several factors to be considered with a 41210 Bridge PCI/PCI-X design. These include the PCI IDSEL, PCI RCOMP, PCI Interrupts and PCI arbitration.

8.1 Interrupts

PCI Express provides interrupt messages that emulate the legacy wired mechanism. This allows IO devices to signal PCI-style interrupts using a pair of ASSERT and DEASSERT messages This message pairing preserves the level-sensitive semantics of the PCI interrupts on PCI Express.
The 41210 Bridge uses four interrupts - A_INTA:A_INTD on bus A segment and four interrupts B_INTA:B_INTD that corresponding to the four interrupts defined in the PCI specification. The 41210 Bridge routes its PCI interrupt pins and the internal interrupts, to PCI Express INTx interrupts according to Table 4.
Table 4. INTx Routing Table
A_INT# Interrupt Pins B_INT# Interrupt Pins PCI Express INTx Message
A_INTA B_INTA INTA A_INTB B_INTB INTB A_INTC B_INTC INTC A_INTD B_INTD INTD
The 41210 Bridge will use its p rimary bus number and device number in the Requester ID field for the PCI Express INTx messages. As stated in the PCI Express specification, the function number is reserved for interrupt messages and will always be 0.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 31
PCI-X Layout Guidelines
Note: PCI Express Assert_INTx/Deassert_INTx messages are not inhibited by the BME bit.

8.1.1 Interrupt Routing for Devices Behind a Bridge

Given the legacy interrupt sharing scheme shown in Table 4, to get the best legacy interrupt performance (by reducing interrupt sharing), adapter boards have to select the appropriate A_INTX#, B_INTX# (where X is A, B, C or D) input pin to use on each PCI bus segment. The chosen interrupt input also imposes a PCI device number requirement for the interrupt source as specified in the PCI-to-PCI Bridge specification and reproduced in Table 5
Table 5. Interrupt Binding for Devices Behind a Bridge
.
Device Number on
Secondary Bus
a
. 4, 8b, 12, 16, 20, 24, 28
-
b
1, 5, 9
, 13, 17, 21, 25, 29
b
2, 6, 10
3, 7, 11
a. Device number 0 is reserved for the Bridge and should not be assigned to secondary devices. b. AD[27:24] which correspond to devices 11:8 should not be used for IDSEL# connections as these signals are used
, 14, 18, 22, 26, 30
b
, 15, 19, 23, 27, 31
when accessing the extended configuration space in the bridge from the secondary bus.
Interrupt Pin on Device Interrupt on 41210 Bridge
INTA# INTA# INTB# INTB# INTC# INTC# INTD# INTD# INTA# INTB# INTB# INTC# INTC# INTD# INTD# INTA# INTA# INTC# INTB# INTD# INTC# INTA# INTD# INTB# INTA# INTD# INTB# INTA# INTC# INTB# INTD# INTC#

8.2 PCI Arbitration

The 41210 Bridge supports a high-performance internal PCI arbiter that supports up to seven masters on each PCI segment A and B PCI Buses. The request inputs into the internal arbiter include: six external request inputs and 1 internal request input. All request inputs to the internal arbiter are split into two groups, a high priority group and a low priority group. Any master, including the internal master , can be programmed to be in either of the two group s. This could also mean that all the request inputs into the arbiter could be in one single group. Within a group, priority is round-ro bi n. The ent i re lo w- priority group represents on e s l ot i n t he high priority group. The 41210 Bridge provides a 16-bit arbiter control register to control two aspects of the internal arbiter behavior:
32 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Priority group for a master (i.e., whether a master is in low priority group or high priority
group).
Bus parking on last PCI agent or the bridge.
By default the arbiter parks the bus on the bridge and drives the A/D, C/BE# and PAR lines to a known value while the bus is idle.

8.2.1 PCI Resistor Compensation

Figure 16 provides the recommended resistor co mpensation pin termination for the PCI A and PCI
B buses.
Figure 16. PCI RCOMP
RCOMP
100
PCI-X Layout Guidelines
– 1%

8.3 PCI General Layout Guidelines

For acceptable signal integrity with bus speeds up to 133MHz it is important to PCB design layout to have controlled impedance.
Signal traces should have an unloaded impedance of 60 +/- 10% Ω.
Signal trace velocity should be roughly 150 – 190ps/inch
There are a couple of general guidelines which should be used when routing your PCI bus signals:
Av oid routing signals > 8”.
The following signals have no length restrictions: A_INTA#, A_INTB#, A_INTC#,
A_INTD#, B_INTA#, B_INTB#, B_INTC#, B_INTD# and TCK, TDI, TDO, TMS and TRST#. Most PCI-X signals are timing critical. These signals have length restrictions for propagation, setup, and hold requirements. Table 6 shows the PCI-X signals.
B2718 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 33
PCI-X Layout Guidelines
Table 6. PCI-X Signals
A PCI Bus Segment: A_ACK64#, A_AD[63:0], A_C BE _ [7: 0] # , A_DEVSEL#, A_FRAME#,
A_GNT_[5:0]#, A_IRDY#, A_LOCK#, A_PAR64, A_REQ64#, A_REQ_[5:0]#,
Timing Critical Signals
Reset Signals
Non Timing Critica l
Signals
A_STOP#, A_TRDY#, A_CLKO [6: 0 ], A_C LKI B PCI Bus Segment: B_ACK64#, B_AD[63:0], B_C BE _ [7: 0] # , B_DEVSEL#, B_FRAME#,
B_GNT_[5:0]#, B_IRDY#, B_LOCK#, B_PAR64, B_REQ64#, B_REQ_[5:0]#, B_STOP#,B_ TRDY#, B_CLKO[6:0], B_CLKI
A PCI Bus Segment: A_RST#, A_PME# B PCI Bus Segment: B_RST#, B_PME#
A PCI Bus Segment: A_133EN, A_IRQ[15:0]#, A_M 66EN, A_PCIXCAP, A_PERR#, A_SERR# B PCI Bus Segment: B_133EN, B_IRQ[15:0]#, B_M 66EN, B_PCIXCAP, B_PERR#, B_SERR#
Table 7. PCI/PCI-X Frequency/Mode Straps
A_PCIXCAP, B_PCIXCAP
00XPCI 33 01XPCI 66
PCI-X 66MHz cards connect this signal to ground through a 10K ±5% resistor in parallel with a
0.01uF ±10% capacitor. PCI-X 133 MHz cards connect
PCIXCAP to ground through a
0.01uF ±10% capacitor. PCI-X 133 MHz cards connect
PCIXCAP to ground through a
0.01uF ±10% capacitor.
A_M66EN,
B_M66EN
XXPCI-X 66
X0PCI-X 100
X1PCI-X 133
A_133EN,
B_133EN
(on board)
Note: All signals sampled on the rising edge of PERST#.

8.3.1 PCI Pullup Resistors Not Required

PCI control signals on the 41210 Bridge do NOT require pullup resistors on the adapter card to ensure that they contain stable values when no agent is actively driving the bus. These include:
A_ACK64#, A_AD[63:32], A_CBE#[7:4], A_DEVSEL#, A_FRAME#, A_INTA#, A_INTB#, A_INTC#, A_INTD#, A_IRDY#, A_PERR#, A_PAR, A_GNT#[5:0], A_REQ#[5:0], A_LOCK#, A_PAR 64, A_RE Q6 4#, A_S ERR #, A_STOP#, A_TRDY#, B_ACK64#, B_AD[63:32],
Bus
Mode/
Freq
34 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
B_CBE#[7:4], B_DEVSEL#, B_FRAME#, B_INTA#, B_INTB#, B_INTC#, B_INTD#, B_IRDY#, B_PERR #, B_PAR, B_GNT #[5 :0], B_REQ#[5:0], B_LOCK#, B_PAR64, B_REQ64#, B_SERR#, B_STOP# , and B_TRDY#.

8.4 PCI Clock Layout Guidelines

The PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0b compliant, allows a maximum of 0.5 ns clock skew timing for each of the PCI-X frequencies: 66 MHz, 100 MHz and 133 MHz. A typical PCI-X application may require separate clock point-to-point connections distributed to each PCI device. The 41210 Bridge provides seven b uf f ered clocks on t he PC I bus to connect to multiple PCI-X devices. The Figure 17 shows the use of four PCI “A” clock outputs and length matching requirements. These same guidelines apply to the 41210 Bri dge PC I “B” clock outputs. The recommended clock buffer layout are specifie d as fo llows:
Match each of the used the 41210 Bridge output clock lengths A_CLK[6:0] and B_CLK[6:0]
to within 0.1” to help keep the timing within the 0.5 ns maximum budget.
Keep the distance between the clock lines and other signals “d” at least 25 mils from each other.
Keep the distance between the clock line and itself “a” at a minimum of 25mils apart (for
serpentine clock layout).
A_CLKIN gets connected to A_CLKO6 through a 22 +/- 1% resistor and likewise for
B_CLKIN is connected to B_CLKO6 through a 22
PCI-X Layout Guidelines
resistor.
The 22 +/- 1% resistor is within 500 mils of A_CLKO.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 35
PCI-X Layout Guidelines
Figure 17. PCI Clock Distribution and Matching Requirements
22
9
A_CLKIN
a
®
Intel
41210
Bridge
A_CLKO0 A_CLKO1 A_CLKO2 A_CLKO3
A_CLKO4
A_CLKO6
9
22
22
9
d
9
22
22
9
X0
X1
X2
X3
PCI
Device 1
PCI
Device 2
PCI
Device 3
PCI
Device 4
PCI Bus
22 9
Notes:
– PCI Clock Lengths X0, X1, X2, X3 and X4 should be matched within 0.1 inch of each other. – Minimum separation between two different CLKs, "d". – Minimum separation between two segments of the same CLK line, "a".
X4
PCI
Device 5
B1499-04
36 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Table 8. PCI-X Clock Layout Requirements Summary
Parameter Routing Guidelines
Signal Group PCI Clocks B_CLKO[6:0], A_CLK[6:0] Reference Plane Route over unbroken ground or power plane Stripline Tr ace Width 4 mils Stripline Trace Spacing: Separation between two
different clock lines, “d” clock lines Stripline Trace Spacing: Separation between two
segments of the same clock line (on serpentine layout), “a” dimension
Stripline Tr ace Sp acing: Separation between clocks and other lines
Length Matching Requirements
Total Length of the 41210 Bridge PCI CLKs on the adapter card
A_CLKIN, B_CLKIN Series Termination
A_CLK[6:0], B_CLK[6:0] Series Termination
Routing Guideline 1 Routing Guideline 2 Minimize number of vias
25 mils center to center from any other signal
25 mils center to center from any other signal
50 mils center to center from any other signal All 41210 Bridge Output Clocks B_CLK0[6:0] and
A_CLK[6:0] connected to devices must be length matched to 0.1 inch of each other.
The clock feedback line lengths from A_CLKOUT to A_CLKIN and B_CLKOUT to B_CLKIN should be length matched to all other clock lines within 0.1”.
10” -14” Connect A_CLKIN to one end of a 22 +/- 1% resistor
and the other end connected to A_CLKOUT and connect B_CLKIN to one end of a 22 resistor and the other end connected to B_CLKOUT
Each of the clock outputs A_CLKO[6:0] and B_CLK[6:0] should have series 22 resistor located within 500 mils of the 41210 Bridge clock output.
Point to point signal routing should be used to keep the reflections low.
PCI-X Layout Guidelines
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 37
PCI-X Layout Guidelines

8.5 PCI-X Topology Layout Guidelines

The PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0b compliant, recommends the following guidelines fo r the numb er of l oads for you r PCI-X des igns. A ny d eviation f rom t hese maximum values requires close attention to layout with regard to loading and trace lengths.
Table 9. PCI-X Slot Guidelines
Frequency Maximum Loads Maximum Number of Slot s
66 MHz 8 4 100 MHz 4 2 133 MHz 2 1

8.6 Intel® 41210 Serial to Parallel PCI Bridge Design Guide Layout Analysis

The following sections describes layout recommendations based on the presilicon signal integrity analysis. This analysis was conducted using the following parameters:
Card stack up: 60 +/- 15% single-ended impedance
Driver Model 41210 Bridge IBIS
Receiver Model: generic models for PCI-X and PCI
Driver Package Model: Preliminary 41210 Bridge Model
Cross talk and ISI impact on timing were not modeled
38 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

8.6.1 Embedded PCI-X 133 MHz

This section lists the routing recommendations for PCI-X 133 MHz without a slot. Figure 18 shows the block di agram of this topology and Table 10 describes the routing recommendations.
Figure 18. Embedded PCI-X 133 MHz Topology
TL1
PCI-X Layout Guidelines
EM1
TL_EM2 TL_EM1
EM2
Table 10. Embedded PCI-X 133 MHz Routing Recommendations
Parameter Routing Guideline for Lower AD Bus
Reference Plane Route over an unbroken ground plane Board Impedance 60 +/- 15% Stripline Trace Spacing 12 mils from edge to edge Microstrip Trace Spacing 18 mils, from edge to edge Break Out 5 mils on 5 mils spacing. Maximum length of breakout region can be 500 mils Group Spacing Spacing from other groups: 25 mils min, edge to edge Trace Length 1 (TL1): From
41210 Bridge signal Ball to first junction
Trace Length 3 junction of TL_EM1 and TL_EM2 to the embedded device
Length Matching Requirements:
Number of vias 3 vias max per path
1.75” min - 4.0” max
1.25” min - 3.25” max
Clocks coming form the clock driver must be on the same layer and length matched to within 25 mils.
B2719 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 39
PCI-X Layout Guidelines

8.6.2 Embedded PCI-X 100 MHz

This section lists the embedded routing recommendations for PCI-X 100 MHz. Figure 19 shows the block diagram of this topology and Table 11 describes the r outing reco mmendatio ns.
Figure 19. Embedded PCI-X 100 MHz Topology
TL1
EM1
TL_EM3
TL_EM2
TL_EM1
Table 11. Embedded PCI-X 100 MHz Routing Recommendations
Parameter Routing Guideline for Lower AD Bus
Reference Plane Route over an unbroken ground plane Board Impedance 60 +/- 15% Stripline Trace Spacing 12 mils from edge to edge Microstrip Trace Spacing 18 mils, from edge to edge Break Out 5 mils on 5 mils spacing. Maximum length of breakout region can be 500 mils Group Spacing Spacing from other groups: 25 mils min, edge to edge Trace Length 1 (TL1): From
41210 Bridge signal Ball to first junction
Trace Length: TL_EM1: from 41210 Bridge signal ball to the first embedded device
Trace Length TL_EM2 ­TL_EM3: from junction to the embedded device
Length Matching Requirements:
Number of vias 4 vias max per path
0.5” min - 3.0” max
2.5” min - 3.5” max
1.5” min - 3.5” max
Clocks coming form the clock driver must be on the same layer and length matched to within 25 mils.
EM3
EM2
B2720 -01
40 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

8.6.3 PCI-X 66 MHz Embedded Topo logy

Figure 20 and Table 12 provide routing details for a topology with an embedded PCI-X 66 MHz
application.
Figure 20. PCI-X 66 MHz Embedded Routing Topology
PCI-X Layout Guidelines
TL1
EM1
TL2
TL_EM2 TL_EM1
EM2
EM3
TL3
TL_EM4 TL_EM3
EM4
Table 12. PCI-X 66 MHz Embedded Routing Recommendations
Parameter Routing Guideline for Lower AD Bus
Reference Plane Route over an unbroken ground plane Board Impedance 60 +/- 15% Stripline Trace Spacing 12 mils edge to edge Microstrip Trace Spacing 18 mils, edge to edge Break Out 5 mils on 5 mils. Maximum length of breakout region can be 500 mils Group Spacing Spacing from other groups: 25 mils min, edge to edge Trace Length 1 (TL1): From
41210 Bridge signal Ball to first junction
Trace Length TL2 to TL4 ­between junctions
Trace Length TL_EM1 to TL_EM8 from junction connector to the embedded device
Length Matching Requirements:
Number of vias 4 vias max.
1.0” - 5.0” max
1.0” min - 2.5” max
2.0” min - 3.0” max
Clocks coming form the clock driver must be length matched to within 25 mils and routed identical in layers.
EM5
EM6
TL_EM6 TL_EM5
EM7
TL4
TL_EM8 TL_EM7
EM8
B2721 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 41
PCI-X Layout Guidelines

8.6.4 PCI 66 MHz Embedded Topology

Figure 21 and Table 13 provide routing details for a topology with an embedded PCI 66 MHz
design.
Figure 21. PCI 66 MHz Embedded Topology
Table 13. PCI 66 MHz Embedded Table
Parameter Routing Guideline for Lower AD Bus
Reference Plane Route over an unbroken ground plane Board Impedance 60 +/- 15% Microstrip Trace Spacing 18 mils center to center Stripline Trace Spacing 12 mils center to center Group Spacing Spacing from other groups: 25 mils min, edge to edge
Breakout
Trace Length 1 TL1: From 41210 Bridge signal Ball to first junction
Trace Length TL2 between junctions 0.5” min - 3.5” max Trace Length TL_EM1 to TL_EM4 from junction to
embedded devices Length Matching Requirements
Number of vias 4 vias max.
P
TL1
EM1
TL2
TL_EM2 TL_EM1
EM2
5 mils on 5 mils spacing. Maximum length of breakout region can be 500 mils.
5.0” max
2.0” min - 3.0” max
Clocks coming from the clock driver must be length matched to within 25 mils.
EM3
TL_EM4 TL_EM3
EM4
B2722 -01
42 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

8.6.5 PCI 33 MHz Embedded Mode Topology

Figure 22 and Table 14 provide routing details for a topology with an embedded PCI 33 MHz
design.
Figure 22. PCI 33 MHz Embedded Mode Routing Topology
PCI-X Layout Guidelines
TL1
EM1
TL2
TL_EM2 TL_EM1
EM2
EM3
TL_EM4 TL_EM3
EM4
EM5
TL3
EM6
Table 14. PCI 33 MHz Embedded Routing Recommendations
Parameter Routing Guideline for Lower AD Bus
Reference Plane Route over an unbroken ground plane Board Impedance 60 +/- 15% Stripline Trace Spacing 12 mils, edge to edge Microstrip Trace Spacing 18 mils edge to edge Group Spacing Spacing from other groups: 25 mils min, edge to edge Breakout 5 mils on 5 mils spacing. Maximum length of breakout region can be 500 mils. Trace Length 1 TL1: From
41210 Bridge signal Ball to first junction
Trace Length TL2 to TL5 ­between junctions
Trace Length TL_EM1 to TL_EM10 from junction to embedded devices
Length Matching Requirements
5.0” max
0.5” min - 3.5” max
2.0” min - 3.0” max
Clocks coming from the clock driver must be length matched to within 25 mils.
TL_EM6 TL_EM5
TL4
EM7
EM8
TL_EM8 TL_EM7
EM9
TL5
TL_EM10 TL_EM9
EM10
B2723 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 43
PCI-X Layout Guidelines
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44 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

PCI Express Layout 9

This section provides an overview of the PCI-Express stackup recommended based on Intel presimulation results. For additional information, refer to the Intel® 41210 Serial to Parallel PCI Bridge Developer’s Manual or the PCI Express Specification, Revision 1.0a from the
www.pcisig.com

9.1 General recommendations

PCI Express is a serial differential low-voltage point-to-point interconnect. The PCI Express was designed to support 20 inches between components with stand ard FR 4. The 41210 Bridge supports x8 lanes. PCI-Express requires special considerations be made for interconnect losses, jitter, crosstalk and mode conversions. The below list provides some general gui delines for t he layout of a PC I­Express trace:
1. Jitter: Trace lengths of a PCB trace can introduce around 1 to 5 ps of jitter and 0.35 to 0.5 dB
of loss per inch of differential pair. An add-in card the trace length from edge-finger pad to device is limited to 3 inches.
2. Matching within pair: Trace lengths of matching differential pairs are required to be matched
within +/-5 mil delta. Each net within a differential pair should be length matched on a segment-by-segment basis at point of discontinuity such as an breakout area, routes between vias, routes between AC coupling capacitors and connector pins.
website.
3. Trac e Sym met ry: T race Symmetry is required between two traces of the same differential pair.
4. Vias: Vias contribute 0.5 to 1.0 dB/via toward the loss budget. Vias on an add-in card should
be limited to one near the breakout section of the pads and one near the edge finger.
5. Bends: Trace bends should be kept to a minimum. If bends are used they should be at a 45-
degree angle or smaller. The number of left and right bends should be matched as closely as possible to even out the overall lengths of each segment of the differential pair.
6. AC Coupling capacitors: AC coupling capacitor with a value of 75nF to 200nF should line
up at the same location from one trace to the other within the pair. The 0402 size capacitor with a small pad size is highly recommended. The breakout from the capacitor should be symmetrical for both signal traces in the differential pair.
7. Connector pins: Length compensation for the connector pins of the differential pair being
offset from each other the PCB trace should be considered.
8. Ground Plane Refer encing: Ground plan e referencing is require d along the entire route of the
differential pair. Traces routed near the edge should maintain a 40 mil air gap to the edge. Layer switching should also maintain the ground plane. Grounds between planes should be connected with stitching vias (with one to three recommended per differential pair).
9. Breakout Areas: Breakout areas near a device package should be limited to 500 mils in lengths.
The necking down to a smaller trace width should be symmetrical on the differential pair.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 45
PCI Express Layout

9.2 PCI-Express Layout Guidelines

The layout guidelines for PCI-Express were developed for an adapter card topologies. The models and assumptions used in development of these guidelines were as follows:
Add-In Card Stackup: 60 Ω single-ended impedance
Target Differential Impedance: 100 Ω +/- 20%.
Driver Model: 41210 Bridge PCI-E IBIS
Receiver Model: 41210 Bridge PCI-E IBIS. Specification model did not meet specifications
Driver Package Model: Preliminary 41210 Bridge model.
No receiver package model used since specification eye is at package pin.
Assumed that traces in a lane could be routed totally on microstrip, totally on stripline, or a
mixture of microstrip and stripline.
AC coupling capacitors were modeled as a parasitic resistor and inductor in series.
Add-in card was modeled as micro-strip routes only.
No vias were modeled at this time.
Only the receiver eye was evaluated. The next revision will evaluate the eye at the transmitter
and connector as well as the receiver.

9.3 Adapter Card Layout Gu idelines

Table 15. Adapter Card Routing Recommendations (Sheet 1 of 2)
Parameter Routing Guidelines
Reference Plane Route over an unbroken ground plane Target Single Ended
Impedance Target Differential
Impedance Microstrip and Stripline Trace
Width
Microstrip Trace Spacing
Group Spacing Spacing from other groups: 25 mils minimum, center to center Transmit Trace Length
(41210 Bridge signal pin to AC coupling capacitor.)
Transmit Trace Length (AC coupling capacitor to card edge finger.)
60 nominal
100 +/- 20% Differential Impedance
4 mils Intrapair: 10 mils center-to-center
Interpair: 30 mils center-to-center 22 mils. center to center (pair to pair). Transmit and Receive pairs should be interleaved. If no interleaving, then inter
pair spacing should be increased to 50 mils (c2c). Center to center of inter pair is defined as center of Positive of one pair to Center of Negative of the next or vice versa
0.25”- 5.0” max
1.00”- 4.5” max
46 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Table 15. Adapter Card Routing Recommendations (Sheet 2 of 2)
Receive Trace Length (Card edge finger to 41210 Bridge receiver pin
Length Matching Requirements:
Number of vias 4 max
1.0” min - 6.0” max
Total allowable intra-pair length mis-match must not exceed 25 mils. Each routing segment should be matched as close as possible. Total skew across all lanes must be less than 20 ns. See the PCI-Express Desktop Design Guidelines for additional routing requirements
PCI Express Layout
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 47
PCI Express Layout
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48 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

Circuit Implementations 10

This chapter describes 41210 Bridge circuit implementations.

10.1 41210 Bridge Analog Voltage Filters

The Intel® 41210 Serial to Parallel PCI Bridge requires several external analog voltage filter circuits to be placed on the system board, three for the PCI interface, one for the PCI Express interface, and one for the bandgap voltage. The 41210 Bridge lists the recommended filter values for these filter circuits -- any one of the filter circuits can use any one of the four R, L and C combinations shown in Table 16, except that configuration number 4 cannot be used for the PCI Express analog voltage filter.
Table 16. Recommended R, L and C Values for 41210 Bridge Analog Filter Circuits
Config R L C
1
2
3
a
4
a. Configuration number 4 cannot be used for the PCI Express analog voltage filter.
0.5 ±1% 1/16W
0.5 ±1% 1/16W
0.5 ±1% 1/16W
1.0 ±1% 1/16W
4.7uH ±25%
PCI, PCI-E: 45mA
Bandgap: 30mA
4.7uH ±20 PCI, PCI-E: 45mA Bandgap: 30mA%
4.7uH ±20%
PCI, PCI-E: 45mA
Bandgap: 30mA
4.7uH ±20% PCI: 45mA
Bandgap: 30mA
33uF ±20%
6.3V
22uF ±20%
6.3V
2x10uF ±20%
6.3V
10uF ±20%
6.3V
Additional notes: L (Inductor)
— L must be magnetically shielded —ESR: max < 0.4
— rated at 45mA (or 30mA for bandgap circuit only)
C (Capacitor)
—ESR: max < 0.5
— ESL < 3.0nH
R (Resistor)
—1/16W
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 49
Circuit Implementations

10.1.1 PCI Analog Voltage Filters

The following filter circuit is recommended for the PCI interface. Three separate, identical versions of this circuit should be placed on the system board, one for each VCCAPCI[2:0] pin on the Intel® 41210 Serial to Parallel PCI Bridge.
Figure 23. PCI Analog Voltage Filter Circuit
Board Trace:
Trace Width > 25 mils Trace Spacing < 10 mils Trace Length < 600 mils
VCC
L
R
Board Route
Traces
C
Breakout
Traces
Breakout Trace:
Trace Width > 6 mils Trace Spacing < 6 mils Trace Length < 600 mils
VCCAPCI[2:0]
Intelfi 41210
Bridge
VSS
Note: Three of these PCI filter circuits must be placed on the system board, one for each of the
VCCAPCI[2:0] pins on the Intel® 41210 Serial to Parallel PCI Bridge.
Place C as close as possible to package pin.
R must be placed between VCC15 and L.
Route VCCPCI[x] and VSS as differential traces.
VCCPCI[x] and VSS traces must be ground referenced (No VCC15 references).
Max total board trace length = 1.2”.
B2724 -01
Min trace space to other nets = 30 mils.

10.1.2 PCI Express Analog Voltage Filter

Figure 24 shows the PCI Express Analog Voltage Circuit.
50 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Figure 24. PCI Express Analog Voltage Filter Circuit
Circuit Implementations
Note: .
Board Trace:
Trace Width > 25 mils Trace Spacing < 10 mils Trace Length < 600 mils
VCC
L
R
Board Route
Traces
C
Breakout
Traces
Breakout Trace:
Trace Width > 6 mils Trace Spacing < 6 mils Trace Length < 600 mils
VCCAPE
Intelfi 41210
Bridge
VSSAPE
Place C as close as possible to package pin.
R must be placed between VCC15 and L.
Route VCCAPE and VSSAPE as differential traces.
VCCAPE and VSSAPE traces must be ground referenced (No VCC15 references).
Max total board trace length = 1.2”.
B2725 -01
Min trace space to other nets = 30 mils.

10.1.3 Bandgap Analog Voltage Filter

Figure 25 Shows the Bandgap Analog Voltage Filter.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 51
Circuit Implementations
Figure 25. Bandgap Analog Voltage Filter Circuit
Note: .
Board Trace:
Trace Width > 25 mils Trace Spacing < 10 mils Trace Length < 600 mils
2.5 V
Note: Ground VSSBGPE at capacitor
Board Route
Traces
L
R
C
VSS
Breakout
Traces
Breakout Trace:
Trace Width > 6 mils Trace Spacing < 6 mils Trace Length < 600 mils
VCCBGPE
Intelfi 41210
Bridge
VSSBGPE
Place C as close as possible to package pin.
R must be placed between the 2.5V supply and L.
Route VCCBGPE and VSSBGPE as differential traces.
VCCBGPE and VSSBGPE traces must be ground referenced (No 2.5V references).
VSSBGPE should be grounded at the capacitor.
B2726 -01
Max total board trace length = 1.2”.
Min trace space to other nets = 30 mils.
52 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Circuit Implementations

10.2 Intel® 41210 Serial to Parallel PCI Bridge Reference and Compensation Pins

There are three compensation pins on Intel® 41210 Serial to Parallel PCI Bridge. PE_RCOMP[1:0] are two separate pins that provide voltage compensation for the PCI Express
interface on the Intel® 41210 Serial to Parallel PCI Bridge. The nominal compensation voltage is
0.5V. An external 24.9 resistor can be used to for both of these signals.
RCOMP is an analog PCI interface compensation pin, pro viding 0. 75V to the Intel® 41 210 Serial to Parallel PCI Bridge. A 100 to ground.
These implementations are shown in Figure 26.
Figure 26. Reference and Compensation Circuit Implementations
±1% pullup resistor shoul d be us ed to connect to VCC15. A single pullup
±1% pulldown resistor should be used to connect the RCOMP pin
VCC
Intelfi 41210
Bridge
R1 = 24.9 – 1%
R3 = 100 – 1%
0.5 V
0.5 V
0.75 V
PE_RCOMP[0] PE_RCOMP[1]
RCOMP
B2727 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 53
Circuit Implementations

10.2.1 SM Bus

The SMBus interface does not have configuration registers. The SMBus address is set by the states of pins SMBUS[5] and SMBUS [3:1] when PERST# is asserted as described in Table 17.
Table 17. SMBUs Address Configuration
Refer to Section 2.4 for details on how to use the SMBus to initialize 41210 Bridge registers with a microcontroller.
Bit Value
71 61 5SMBUS[5] 40 3SMBUS[3] 2SMBUS[2] 1SMBUS[1]
54 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
41210 Bridge Customer Reference
Boards 11
This chapter describes the 41210 Bridge Customer Reference Board (CRB).

11.1 Board Stack-up

The proposed layout of the PCB is eight layers with the following stackup:
Signal #1 (Top/Component Side)
Ground Plane: GND
Signal #2
Power Plane
Power Plane
Signal #3
Ground Plane
Signal #4 (Bo t t om)
The permittivity constant Er = 4.5
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 55
41210 Bridge Customer Reference Boards
T able 18. CRB Board Stackup
Layer Type
1 Signal 2.00 1/2 + plating
Prepreg 4.50
2 Plane: GND 1.20 1
Core 4.80
3 Signal 1.20 1
Prepreg 14.00
4 Plane: PWR 1.20 1
Core 3.8
5 Plane: PWR 1.20 1
Prepreg 14.00
6 Signal 1.20 1
Core 4.80
7 Plane: Power 1.20 1
Prepreg 4.50
8 Signal 2.00 1/2 + plating
Est. Total
Thickness
Thickness
(mils)
62 +/- 7
Copper Weight

11.2 Material

The following materials are used with the 41210 Bridge CRB:
FR-4, 0.062 in. +/- .007, 1.0 oz Copper Power/GND.
Full length PCI Raw Card (3.3V Universal) 6.2” high x 7.00” long max with ½ inch cut away.

11.3 Impedance

Most signal layers require controlled Impedance of 60 Ω +/- 5% microstrip or stripline where appropriate.
Differential signals for the PCI-E interface require matched 100 as matched 50
resistances referenced to ground.
differential termination realized
56 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

11.4 Board Outline

Figure 27 provides the mechanical outline of the 41210 Bridge CRB.
Figure 27. Mechanical Outline of the 41210 Bridge
41210 Bridge Customer Reference Boards
U1
Intel
41210
Bridge
B2728 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 57
41210 Bridge Customer Reference Boards
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58 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide

Design Guide Checklist 12

This checklist highlights design considerations that should be reviewed prior to manufacturing an adapter card that implements the 41210 Bridge product. The items contained within this checklist attempt to address important connections to these devices and any critical supporting circuitry. This is not a complete list and does not guarantee that a design will function properly.
T able 19. PCI Express Interface Signals
Signals Recommendations Reason/Impact
REFCLKn, REFCLKp
PE_RCOMP[1:0]
PERP[7:0] PERN[7:0]
PETP[7:0] PETN[7:0]
Must be connected to clock from a PCI Express connector for add-in card designs or to a 100MHz oscillator for an embedded design.
24.9±1% pullup resistor to 1.5V . A single resistor can be used for both signals. Place resistor as close as possible to REFCLKn, REFCLKp pins.
For X1 mode, only signals PERp[0] and PERn[0] or PERp[7] and PERn[7] are used.
For X4 mode, only signals PERp[3:0] and PERn[3:0] are used.
For X8 mode, all of these signals, PERp[7:0] and PERn[7:0], are used.
For X1 mode, only signals PETp[0] and PETn[0] or PETp[7] and PETn[7] are used.
For X4 mode, only signals PETP[3:0] and PETN[3:0] are used.
For X8 mode, all of these signals, PETP[7:0] and PETN[7:0], are used.
PCI Express compensation pin.
0.5V nominal.
PCI Express data serial inputs (differential data receive signals).
PCI Express data serial inputs (differential data transmit signals).
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 59
Design Guide Checklist
Table 20. PCI/PCI-X Interface Signals
Signals Recommendations Reason/Impact
X_AD[63:32] X_CBE[7:4]# X_DEVSEL# X_FRAME# X_IRDY# X_TRDY# X_STOP# X_PERR# X_SERR# X_REQ[5:0]# X_GNT[5:0]# X_LOCK# X_PAR X_PAR64 X_ACK64# X_REQ64#
A_133EN B_133EN
No external pullup resistors required on system board.
Only relevant when running in PCI-X Mode (X_PCIXCAP = 1).
Determines the max PCI-X Mode 1 frequency for a particular segment (100 MHz or 133 MHz):
0 = 100 MHz PCI-X max frequency 1 = 133 MHz PCI-X max frequency
41210 Bridge has internal pullup resistors on these signals.
X_AD[31:0] and X_CBE#[3:0] signals do not require pullups according to the PCI Specification.
Sampled on the rising edge of PERST#.
A_INTA#, A_INTB#, A_INTC#, A_INTD#, B_INTA#, B_INTB#, B_INTC#, B_INTD#
Use an 8.2K pullup resistor to VCC33. This resistor is located on the system board.
No pullup resistors required on these signals.
The 41210 Bridge has internal pullup resistors on these signals.
60 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Table 20. PCI/PCI-X Interface Signals
Signals Recommendations Reason/Impact
Controls frequency of the PCI segment when running in conventional PCI mode (33 MHz or 66 MHz):
0 = 33 MHz PCI 1 = 66 MHz PCI
A_M66EN B_M66EN
A_PCIXCAP B_PCIXCAP
• Pull-up using a 8.2K resistor when the PCI bus is to operate at 66 MHz and not already pulled up by system board. This signal is grounded for 33 MHz operation.
• Connect M66EN to a 0.01 µF capacitor located with-in 0.25 inches of the M66EN pin on the PCI connector (for designs with secondary PCIX bus slots only).
Connects directly to the PCIXCAP pin on the PCI slot. Connect to VCC33 through an 8.2K pullup resistor.
Design Guide Checklist
Sampled on the rising edge of PERST#.
Design without secondary PCI/PCI-
X Slot
— If there is at least one legacy
PCI device on the PCI/PCI-X bus, tie this pin directly to GND.
— If all devices are PCI-X
capable and there is at least one PCI-X device that only supports maximum PCI-X 66MHz on the secondary PCI bus, pull down to GND through 10K parallel with a 0.01uF capacitor.
— If all secondary PCI-X
devices ( and t he bus load ing) support PCI-X 133MHz, connect PCIXCAP to 3.3V through an 8.2K
Design with secondary PCI/PCI-X
Slot
— If there is at least one on
board legacy PCI device on the secondary PCI bus, tie this pin directly to GND.
—Else
series resistor
resistor
Pull up to 3.3V through a
resistor
8.2K
Connect this pin to
PCIXCAP (Pin B38) of the PCI connector. (Assuming bus loading supports up to PCI-X 133MHz)
IDSEL The series resistor on IDSEL should be 200Ω ±5%.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 61
Design Guide Checklist
Table 21. Miscellaneous Signals
Signals Recommendations Reason/Impact
RSTIN# A_STRAP0,
A_STRAP1, A_STRAP2, A_STRAP6,
B_STRAP0, B_STRAP1, B_STRAP2, B_STRAP6
RESERVED [8:1]
CFGRETRY
A_TEST1, A_TEST2, B_TEST1, B_TEST2
A_PME#, B_PME#, A_STRAP[3], A_STRAP[4], A_STRAP[5], B_STRAP[3], B_STRAP[4], B_STRAP[5]
NC17 This signal requires an external pull-up, 8.2Kto 3.3V.
Used for debug purposes. Connect to VCC33 through an 8.2K pullup resistor for normal operation.
These signals REQUIRE external pull-downs to GND on the board 8.2K unless otherwise stated.
Input pin to configure 41210 to retry configuration accesses on it's PCI Express interface.
To retry configuration accesses to the 41210, pull high to
3.3V through a 2K
T o allow configuration accesses to the 41210, ground this
pin through a 2K resistor.
These signals REQUIRE an external pull-up, 8.2K to
3.3V.
resistor.
In normal operating mode, this pin must be tied high.
T able 22. SMBus Interface Signals
Signal Recommendations Reason/Impact
SMBCLK Connect to VCC33 through an 8.2Kpullup resistor. SMBDAT Connect to VCC33 through an 8.2Kpullup resistor.
SMBus addressing: Bit 7----------------’1’ Bit 6----------------’1’ Bit 5---------------SMBUS[5] Bit 4----------------’0’
SMBUS[5], SMBUS[3:1]
Bit 3---------------SMBUS[3] Bit 2---------------SMBUS[2] Bit 1---------------SMBUS[1]
Use 8.2Kresistors as pullups to VCC33 for a ‘1’ and as pulldowns to ground for a ‘0’ to set the SMBus address.
62 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Sampled on the rising edge of PERST#.
Table 23. Power and Ground Signals
Signal Recommendations Reason/Impact
100±1% (1/4 W) pulldown resistor to ground.
RCOMP
The trace impedance of this signal should be < 0.1Ω. Connect to 1.5V power supply.
Note: Linear voltage regulators are recommended when using 1.5 Volt power supplies.
Decoupling:
VCC15
VCC33
VCCAPE
VCCAPCI[2:0] See Figure 23 for circuit. Analog PCI voltage pins.
VCCBGPE
VCCPE
VSS Connect to ground. VSSAPE See Figure 24 for circuit. Analog ground for PCI Express.
VSSBGPE
5 0.1uF caps beneath package (backside of board) 2 1.0 uF caps as close as design rules permit to
package 3 10 uF caps as close as design rules permit to
package Connect to 3.3V power supply.
Decoupling: TBD The platform must insure that the VCC33 voltage rail
be greater than to (or no less than 0.5V below) VCC15 (absolute voltage value at all times during 41210 Bridge operation, including during system power up, power down or any other time during system operation. This can be accomplished by placing a diode (with a voltage drop < 0.5V) between VCC15 and VCC33. Anode will be connected to VCC15 and cathode will be connected to VCC33.
Connect to 1.5V power supply.
Voltage output of the bandgap filter circuit into 41210 Bridge, separated from the rest of the VCC15s. See
Figure 25 for circui t.
Connect to 1.5V power supply. Decoupling: 3 0.1uF caps beneath package (backside of board) 4 1.0 uF caps as close as design rules permit to
package 2 10 uF caps as close as design rules permit to
package
Ground for the bandgap filter circuit, separated from the rest of the VSSs. See Figure 25 for circuit.
Design Guide Checklist
Analog compensation pin for PCI. 0.75V nominal.
1.5V ±5% core voltage.
3.3V ±5% PCI I/O voltage.
1.5V ±3% Analog PCI Express voltage.
2.5V ±3% PCI Express voltage.
1.5V ±3% PCI Express voltage.
Ground reference for all supplies.
Ground for analog bandgap voltage.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 63
Design Guide Checklist
Table 24. JTAG Signals
Signal Recommendations Reason/Impact
TCK If not used for JTAG, leave as No Connect Internal pull-up TDI If not used for JTAG, leave as No Connect Internal pull-up TDO If not used for JTAG, leave as No Connect Internal pull-up TMS If not used for JTAG, leave as No Connect Internal pull-up
TRST# Connect to ground via a 1Kpulldown resistor.
If TAP interface is not used this should be tied to ground.
64 Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
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