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July 2003000First internal draft of this document.
Intel® 41210 Serial to Parallel PCI Bridge Design Guidev
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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viIntel® 41210 Serial to Parallel PCI Bridge Design Guide
About This Document1
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.
1.1Terminology 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)
TermDefinition
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 Guide7
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)
TermDefinition
Layer 1: copper
Prepreg
Layer 2: GND
Core
PCB
Example of a Four-Layer Stack
SSTL_2Series Stub Terminated Logic for 2.5 V
JEDECProvides standards for the semiconductor industry.
A network that transmits a coupled signal to another network is aggressor network.
Aggressor
VictimA network that receives a coupled cross-talk signal from another network is a victim network.
NetworkThe trace of a PCB that completes an electrical connection between two or more components.
StubBranch from a trunk terminating at the pad of an agent.
CRBCustomer Reference Board
Downstream
Upstream
Local memory
DWORD32-bit data word.
Flip Chip
Mode
Conversion
PCI-EPCI-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
8Intel® 41210 Serial to Parallel PCI Bridge Design Guide
Introduction2
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.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide11
Introduction
2.5JTAG
• Compliant with IEEE Standard Test Access Port and Boundary Scan Architecture 1149.1a
2.6Related 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
JTAGSMB Bus
fi
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
12Intel® 41210 Serial to Parallel PCI Bridge Design Guide
2.7Intel®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 Guide13
Introduction
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14Intel® 41210 Serial to Parallel PCI Bridge Design Guide
Package Information3
3.1Package Specification
The 41210 Bridge is in a 567-ball FCBGA package, 31mm X 31mm in size, with a 1.27mm ball
pitch.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide17
Package Information
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18Intel® 41210 Serial to Parallel PCI Bridge Design Guide
Power Plane Layout4
This chapter provides detail s on the decoupling and voltage plan es needed to b ias the 41210 Br idge
package.
4.141210 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
20Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
T a ble 2. 41210 Bridge Decoupling Guidelines
Power Plane Layout
Vol tage PlaneVoltage
PCI/PCI-X
Voltage
PCI/PCI-X
Voltage
PCI/PCI-X
Voltage
Core Voltage1.5VVCC150.106032002.05
Core Voltage1.5VVCC151.008052002.35
Core Voltage1.5VVCC151012062001.92
PCI Express
Voltage
PCI Express
Voltage
PCI Express
Voltage
3.3VVCC330.10603
3.3VVCC331.00603
3.3VVCC33101206
1.5VVCCPE0.106032002.03
1.5VVCCPE108052002.34
1.5VVCCPE1012062001.92
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
4.2Split 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
22Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
41210 Bridge Reset and Power Timing
Considerations5
This chapter describes the 41210 Bridge reset timing considerations.
5.1A_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.
5.2VCC15 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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24Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
General Routing Guidelines6
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
6.1General 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.
6.2Crosstalk
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
aggressorvictim
• 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 methodB. Correct method
A9260-01
6.3EMI 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:
26Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
6.4Power 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.
6.4.1Decoupling
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.
6.5Trace Impedance
All signal layers require contr olled impeda nce 60 Ω +/- 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.
6.5.1Differential Impedance
The PCI Express standard defines a 100 Ω 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:
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
28Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Board Layout Guidelines7
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.
7.1Adapter 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
Ω +/-15%.
VariableType
Solder Mask Thickness (mil)N/A0.80.61.0
Solder Mask E
Core Thickness (mil)N/A2.83.03.2
Core E
Plane Thickness (mil)
Trace Height
Trace Thickness (mil)
Trace Width (mil)Microstrip4.02.55.5
Total Thickness (mil)FR462.056.068.0
(mil)
Preg E
N/A3.653.653.65
r
N/A4.33.754.852113 material
r
Power2.72.52.9
Ground1.351.151.55
13.53.33.7
23.53.33.7
310.59. 911.1
Microstrip4.303.754.852113 material
Stripline14.303.754.852113 material
r
Stripline24.33.754.85
Microstrip1.751.22.3
Stripline1.41.21.6
Stripline4.02.55.5
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]
Microstrip605169
Stripline605169
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
30Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
PCI-X Layout Guidelines8
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.
8.1Interrupts
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.
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.
8.1.1Interrupt 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.
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:
32Intel® 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.
8.2.1PCI 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
Ω
– 1%
8.3PCI 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#,
Note: All signals sampled on the rising edge of PERST#.
8.3.1PCI 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:
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 22Ω +/- 1% resistor and likewise for
B_CLKIN is connected to B_CLKO6 through a 22
PCI-X Layout Guidelines
Ω resistor.
• The 22 +/- 1% Ω 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
36Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Table 8. PCI-X Clock Layout Requirements Summary
ParameterRouting Guidelines
Signal GroupPCI Clocks B_CLKO[6:0], A_CLK[6:0]
Reference PlaneRoute over unbroken ground or power plane
Stripline Tr ace Width4 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 2Minimize 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 22Ω +/- 1% resistor
and the other end connected to A_CLKOUT and
connect B_CLKIN to one end of a 22Ω 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 22Ω 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
8.5PCI-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
FrequencyMaximum LoadsMaximum Number of Slot s
66 MHz84
100 MHz42
133 MHz21
8.6Intel® 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:
• 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
38Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
8.6.1Embedded 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.
Reference PlaneRoute over an unbroken ground plane
Board Impedance60 Ω +/- 15%
Stripline Trace Spacing12 mils from edge to edge
Microstrip Trace Spacing18 mils, from edge to edge
Break Out5 mils on 5 mils spacing. Maximum length of breakout region can be 500 mils
Group SpacingSpacing 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 vias3 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
8.6.2Embedded 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.
Reference PlaneRoute over an unbroken ground plane
Board Impedance60 Ω +/- 15%
Stripline Trace Spacing12 mils from edge to edge
Microstrip Trace Spacing18 mils, from edge to edge
Break Out5 mils on 5 mils spacing. Maximum length of breakout region can be 500 mils
Group SpacingSpacing 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 vias4 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
40Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
8.6.3PCI-X 66 MHz Embedded Topo logy
Figure 20 and Table 12 provide routing details for a topology with an embedded PCI-X 66 MHz
Reference PlaneRoute over an unbroken ground plane
Board Impedance60 Ω +/- 15%
Stripline Trace Spacing12 mils edge to edge
Microstrip Trace Spacing18 mils, edge to edge
Break Out5 mils on 5 mils. Maximum length of breakout region can be 500 mils
Group SpacingSpacing 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 vias4 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_EM6TL_EM5
EM7
TL4
TL_EM8TL_EM7
EM8
B2721 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 41
PCI-X Layout Guidelines
8.6.4PCI 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
ParameterRouting Guideline for Lower AD Bus
Reference PlaneRoute over an unbroken ground plane
Board Impedance60 Ω +/- 15%
Microstrip Trace Spacing18 mils center to center
Stripline Trace Spacing12 mils center to center
Group SpacingSpacing 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 junctions0.5” min - 3.5” max
Trace Length TL_EM1 to TL_EM4 from junction to
embedded devices
Length Matching Requirements
Number of vias4 vias max.
P
TL1
EM1
TL2
TL_EM2TL_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_EM4TL_EM3
EM4
B2722 -01
42Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
8.6.5PCI 33 MHz Embedded Mode Topology
Figure 22 and Table 14 provide routing details for a topology with an embedded PCI 33 MHz
Reference PlaneRoute over an unbroken ground plane
Board Impedance60 Ω +/- 15%
Stripline Trace Spacing12 mils, edge to edge
Microstrip Trace Spacing18 mils edge to edge
Group SpacingSpacing 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_EM6TL_EM5
TL4
EM7
EM8
TL_EM8TL_EM7
EM9
TL5
TL_EM10TL_EM9
EM10
B2723 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 43
PCI-X Layout Guidelines
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44Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
PCI Express Layout9
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
9.1General 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
9.2PCI-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:
• 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.
9.3Adapter Card Layout Gu idelines
Table 15. Adapter Card Routing Recommendations (Sheet 1 of 2)
ParameterRouting Guidelines
Reference PlaneRoute over an unbroken ground plane
Target Single Ended
Impedance
Target Differential
Impedance
Microstrip and Stripline Trace
Width
Microstrip Trace Spacing
Group SpacingSpacing 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 Ω nominal
100 Ω +/- 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
46Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Table 15. Adapter Card Routing Recommendations (Sheet 2 of 2)
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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48Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Circuit Implementations10
This chapter describes 41210 Bridge circuit implementations.
10.141210 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
ConfigRLC
1
2
3
a
4
a.Configuration number 4 cannot be used for the PCI Express analog voltage filter.
0.5Ω ±1%
1/16W
0.5Ω ±1%
1/16W
0.5Ω ±1%
1/16W
1.0Ω ±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
Ω
— rated at 45mA (or 30mA for bandgap circuit only)
C (Capacitor)
—ESR: max < 0.5
Ω
— ESL < 3.0nH
R (Resistor)
—1/16W
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 49
Circuit Implementations
10.1.1PCI 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.
• 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.
52Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Circuit Implementations
10.2Intel® 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
Ω ±1% pullup resistor shoul d be us ed to connect to VCC15. A single pullup
Ω ±1% pulldown resistor should be used to connect the RCOMP pin
VCC
Intelfi 41210
Bridge
R1 = 24.9 Ω – 1%
R3 = 100 Ω – 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
10.2.1SM 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.
BitValue
71
61
5SMBUS[5]
40
3SMBUS[3]
2SMBUS[2]
1SMBUS[1]
54Intel® 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).
11.1Board 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
LayerType
1Signal2.001/2 + plating
Prepreg4.50
2Plane: GND1.201
Core4.80
3Signal1.201
Prepreg14.00
4Plane: PWR1.201
Core3.8
5Plane: PWR1.201
Prepreg14.00
6Signal1.201
Core4.80
7Plane: Power1.201
Prepreg4.50
8Signal2.001/2 + plating
Est. Total
Thickness
Thickness
(mils)
62 +/- 7
Copper Weight
11.2Material
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.
11.3Impedance
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
Ω resistances referenced to ground.
Ω differential termination realized
56Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
11.4Board 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
fi
Intel
41210
Bridge
B2728 -01
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 57
41210 Bridge Customer Reference Boards
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58Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Design Guide Checklist12
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
SignalsRecommendationsReason/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.
24.9Ω ±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
Use an 8.2KΩ 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.
60Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Table 20. PCI/PCI-X Interface Signals
SignalsRecommendationsReason/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 8.2KΩ 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 8.2KΩ 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
Ω series resistor
Ω resistor
•Pull up to 3.3V through a
Ω resistor
8.2K
•Connect this pin to
PCIXCAP (Pin B38) of the
PCI connector. (Assuming
bus loading supports up to
PCI-X 133MHz)
IDSELThe series resistor on IDSEL should be 200Ω ±5%.
Intel® 41210 Serial to Parallel PCI Bridge Design Guide 61
NC17This signal requires an external pull-up, 8.2KΩ to 3.3V.
Used for debug purposes. Connect to VCC33 through
an 8.2KΩ pullup resistor for normal operation.
These signals REQUIRE external pull-downs to GND
on the board 8.2KΩ 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 Ω resistor.
These signals REQUIRE an external pull-up, 8.2KΩ to
3.3V.
Ω resistor.
In normal operating mode, this
pin must be tied high.
T able 22. SMBus Interface Signals
SignalRecommendationsReason/Impact
SMBCLKConnect to VCC33 through an 8.2KΩ pullup resistor.
SMBDATConnect to VCC33 through an 8.2KΩ pullup 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 8.2KΩ resistors as pullups to VCC33 for a ‘1’ and
as pulldowns to ground for a ‘0’ to set the SMBus
address.
62Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
Sampled on the rising edge of
PERST#.
Table 23. Power and Ground Signals
SignalRecommendationsReason/Impact
100Ω ±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
VSSConnect to ground.
VSSAPESee 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
SignalRecommendationsReason/Impact
TCKIf not used for JTAG, leave as No ConnectInternal pull-up
TDIIf not used for JTAG, leave as No ConnectInternal pull-up
TDOIf not used for JTAG, leave as No ConnectInternal pull-up
TMSIf not used for JTAG, leave as No ConnectInternal pull-up
TRST#Connect to ground via a 1KΩ pulldown resistor.
If TAP interface is not used this
should be tied to ground.
64Intel® 41210 Serial to Parallel PCI Bridge D esign Guide
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