82559 Printed Circuit Board (PCB) Design

Transcription

82559 Printed Circuit Board (PCB) Design
82559 Printed Circuit Board
(PCB) Design
Application Note (AP-399)
Revision 1.0
January 1999
Order Number: 739073-001
Revision History
Revision
Date
Revision
Description
Jan. 1999
1.0
First Release
Information in this document is provided in connection with Intel products. No license, express or implied, by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Intel's Terms and Conditions of Sale for such products, Intel assumes no liability
whatsoever, and Intel disclaims any express or implied warranty, relating to sale and/or use of Intel products including liability or warranties relating to
fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Intel products are not
intended for use in medical, life saving, or life sustaining applications.
Intel may make changes to specifications and product descriptions at any time, without notice.
Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Intel reserves these for
future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.
The 82559 may contain design defects or errors known as errata which may cause the product to deviate from published specifications. Current
characterized errata are available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
Copies of documents may be obtained by visiting Intel's website at http://www.intel.com.
Copyright © 1999, Intel Corporation
*Third-party brands and names are the property of their respective owners.
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
Contents
1.0
Introduction......................................................................................................................... 1
1.1
1.2
2.0
Guidelines for Component Placement................................................................................ 1
2.1
2.2
2.3
3.0
References ............................................................................................................ 1
Recommended Reading........................................................................................ 1
Crystals and Oscillators......................................................................................... 2
Termination Resistors ...........................................................................................2
Critical Dimensions................................................................................................ 2
2.3.1 Distance A: Magnetics to RJ-45 (Priority 1) ............................................. 3
2.3.2 Distance B: PHY to Magnetics (Priority 2)................................................ 3
General Trace Routing Considerations ..............................................................................3
3.1
3.2
3.3
3.4
3.5
Trace Routing........................................................................................................4
Trace Geometry .................................................................................................... 5
Trace Length ......................................................................................................... 5
Signal Isolation ...................................................................................................... 5
Power and Ground Connections ........................................................................... 6
4.0
General Power and Ground Plane Considerations ............................................................ 6
5.0
Terminating Unused Connections ...................................................................................... 7
6.0
196-pin Ball Grid Array ....................................................................................................... 8
7.0
Designing Boards for the 196-pin BGA ..............................................................................9
7.1
7.2
7.3
Solder Mask Defined (SMD) Pad .......................................................................... 9
Non-Solder Mask (Copper) Defined Pad.............................................................10
196-pin BGA Routing and Pad Size ....................................................................10
7.3.1 Top Layer Routing..................................................................................11
7.3.2 Bottom Layer Routing.............................................................................12
7.3.3 Analog Signal Routing............................................................................12
Figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Placement of Termination Resistors ............................................................... 2
Critical Dimensions for Component Placement............................................... 3
Printed Working Assembly Layer Stack .......................................................... 4
Trace Routing.................................................................................................. 5
Trace Geometry .............................................................................................. 5
Ground and Power Connections for the Magnetics Module............................ 6
Terminating Unused Connections on the RJ-45 Connector............................ 7
196-pin Ball Grade Array Mechanical Specifications ...................................... 8
Pad Delimitation Options................................................................................. 9
82559 Ball Pattern.........................................................................................10
82559 Top Layer Routing..............................................................................11
Application Note (AP-399)
iii
82559 Printed Circuit Board (PCB) Design
Figure 12. 82559 Bottom Layer Routing ........................................................................ 12
Figure 13. 82559 Analog Signal Routing........................................................................ 13
iv
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
1.0
Introduction
This application note provides guidelines for the physical layout of a printed circuit board (PCB)
design that makes use of the 82559 Ethernet Controller. This document applies to network interface
card and LAN-on-motherboard (LOM) designs.
Fast Ethernet (100 Mbps) uses low voltage differential signaling and drives at least 100 meters of
Category 5 (CAT 5) cable. The stringent requirements of the communications channel places
additional burdens on the PCB designer. Placement, routing, impedance control, and thermal
management have become important criteria in overall design.
1.1
References
The following documents provide additional reference material for 82559-based designs.
• 82559 Fast Ethernet Multifunction PCI/CardBus Controller Datasheet
• Intel Packaging Databook, 1998
1.2
Recommended Reading
• Amkor Technology, Inc. Applications Notes on Surface Mount Assembly of BGA Packages,
January 1998.
• IPC. Implementation of Ball Grid Array and Other High Density Technology, J-STD-013.
2.0
Guidelines for Component Placement
Component placement can affect signal quality, emissions, and temperature of a board design. This
section provides guidelines regarding component placement.
If LAN components are placed close together, stripline design becomes less of an issue. This
includes the layout of the LAN support components such as the crystal, or oscillator, circuitry.
Careful component placement can:
• decrease potential problems directly related to electromagnetic interference (EMI), which may
cause failure of FCC and IEEE test specifications.
• simplify the task of routing traces. To some extent, component orientation also affects the
complexity of trace routing. The objective is to minimize the number of turns and crossovers
between traces.
Minimizing the amount of space required for the Ethernet interface is important because the
interface competes for physical space on the motherboard, near the connector edge. As with most
subsystems, the LAN circuitry needs to be close to the connector (for example, an RJ-45). Thus, it
is imperative that designs be optimized to fit in a very small space.
Application Note (AP-399)
1
82559 Printed Circuit Board (PCB) Design
2.1
Crystals and Oscillators
To minimize the effects of EMI, clock sources should not be placed near I/O ports or board edges.
Radiation from these devices may be coupled onto the I/O ports. Crystals should also be kept away
from the Ethernet magnetics module. The retaining straps of the crystal should be grounded to
reduce the possibility of radiation from the crystal case. Crystals should lay flat against the PC
board to provide better coupling of electromagnetic fields to the board.
2.2
Termination Resistors
PCI Interface
The differential transmit signal pair (TDP/TDN) is terminated with a 100 Ω (1%) resistor, and the
differential receive signal pair (RDP/RDN) is terminated with a 120 Ω (1%) resistor. These
termination resistors should be placed as close to the PHY as possible. These resistors terminate the
entire impedance seen at the termination source (for example, the PHY), including the wire
impedance reflected through the transformer. Figure 1 depicts the placement of the termination
resistors.
R
Magnetics
Module
82559
RJ-45
R
Place termination
resistors as close to
the 82559 as possible.
Figure 1. Placement of Termination Resistors
2.3
Critical Dimensions
There are two critical dimensions to consider during the layout phase of a board design. These
dimensions are identified in Figure 2.
2
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
B
82559
Flash
(optional)
A
Magnetics
RJ-45
EEPROM
Figure 2. Critical Dimensions for Component Placement
2.3.1
Distance A: Magnetics to RJ-45 (Priority 1)
The distance between the magnetics module and the RJ-45 connector (labeled “A” in Figure 2)
should be given the highest priority in board layout. This distance should be kept to less than one
inch of separation. The following trace characteristics are important and should be observed:
• Differential Impedance: The differential impedance should be 100 Ω. The single ended trace
impedance will be approximately 50 Ω; however, the differential impedance can also be
affected by the spacing between the traces.
• Trace Symmetry: Route differential pairs (such as TDP and TDN) with consistent separation
and with exactly the same lengths and physical dimensions (for example, width).
Caution:
2.3.2
Asymmetrical and unequal length traces in the differential pairs contribute to common mode noise.
This can degrade the receive circuit performance and contribute to radiated emissions from the
transmit circuit. If the PHY must be placed more than a couple of inches from the RJ-45 connector,
distance B identified in Figure 2 can be sacrificed. Keeping distance A as short as possible is the
priority.
Distance B: PHY to Magnetics (Priority 2)
Due to the high-speed of signals present, distance B in Figure 2 should be designed to extend less
than one inch between devices. In general, any section of trace that is intended for use with highspeed signals should observe proper termination practices.
Proper signal termination can reduce reflections caused by impedance mismatches between device
and traces. The reflections of a signal may have a high-frequency component that may contribute
more EMI than the original signal itself. For this reason, these traces should be designed to a 100 Ω
differential value.
3.0
General Trace Routing Considerations
Trace routing considerations are important to minimize the effects of cross-talk and propagation
delays on sections of the board where high speed signals exist.
Application Note (AP-399)
3
82559 Printed Circuit Board (PCB) Design
This section provides general as well as 82559-specific trace routing guidelines. Examples from
Appendix A, “82559 Layout Diagrams” in this document are used to illustrate specific routing
results. Depending on the design for manufacturing rules used, an appropriate keep-out zone
around the BGA is required for rework purposes. The requirements for the keep-out zone is
determined by the type of rework equipment used. The example provided is a four-layer design
with the signal run on the top and bottom layers. The power planes are internal to the stack.
Figure 3 shows the layer stack used in this example.
Figure 3. Printed Working Assembly Layer Stack
3.1
Trace Routing
Signal traces should be kept as short as possible to decrease interference from other signals,
including those propagated through power and ground planes. Capacitive loading, which is caused
by the signal trace, can also be reduced by keeping the traces as short as possible.
Note:
Observe the following suggestions to help optimize subsystem and board performance:
• The maximum separation distance between differential pairs should not exceed one tenth of an
inch. However, it is more important to keep the signal trace lengths equal to each other than to
observe the one tenth of an inch separation throughout the route.
• For high-speed signals, the number of corners and vias should be kept to a minimum. If a 90o
turn is required, use two 45o bends instead.
• Traces traces should be routed away from board edges by a distance greater than the trace
height above the ground plane. This allows the field around the trace to couple more easily to
the ground plane rather than to adjacent wires, boards, etc.
• Routing traces and vias under crystals or oscillators should be avoided to reduce the coupling
area.
45°
4
Maximum separation
should be less than
0.1 inch.
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
Figure 4. Trace Routing
As a general rule, traces from clocks and drivers should be placed at a minimum distance from
apertures by a distance that is greater than the largest aperture dimension.
3.2
Trace Geometry
The key factors in controlling trace EMI radiation are the trace length and the ratio of trace-width
to trace-height above the ground plane. To minimize trace inductance, high-speed signals, such as
the clock, and signal layers that are close to a ground plane or power plane should be as short and
as wide as is practical. As shown in Figure 5, this ratio is ideally somewhere between 1:1 and 3:1.
W
H
Ground
1 W 3
<
<
1 H 1
W = Trace Width
H = Height Above Ground Plane
Figure 5. Trace Geometry
To maintain the impedance of a trace, the width of the trace should be modified when changing
from one board layer to another if the two layers are not equidistant from a power or ground plane.
3.3
Trace Length
The traces between decoupling and I/O filter capacitors should be short and as wide as is practical.
Long and thin traces are more inductive and reduce the effectiveness of the decoupling capacitors.
For similar reasons, traces to I/O signals and terminations should be as short as possible. Also,
plated vias to the decoupling capacitors should be larger in diameter to decrease series inductance.
3.4
Signal Isolation
Signals should be separated and grouped by function on separate layers if possible. Physically
grouping together all components associated with one clock trace can reduce the trace length and
radiation. Isolate I/O signals from high speed signals to minimize cross-talk. Cross-talk can
increase both emission and susceptibility to EMI from other signals. Avoid routing high-speed
LAN traces near other high-frequency signals associated with video controller, cache controller,
and CPU, and other similar devices
Application Note (AP-399)
5
82559 Printed Circuit Board (PCB) Design
3.5
Power and Ground Connections
All VCC pins should be connected to the same power supply, and all VSS pins to the same ground
plane of the 82559. For main power and VCC decoupling, the number of capacitors used in the
design may be reduced at the designer’s discretion. For optimized performance, decoupling
capacitors should be placed as close to the 82559 as possible. Optimal performance can be
achieved by placing decoupling capacitors on the backside of the circuit board directly under the
82559. Four to six decoupling capacitors, including two 4.7 µF capacitors, will help improve
performance.
4.0
General Power and Ground Plane Considerations
To properly implement the common mode choke functionality of certain magnetics module (such
as Pulse Engineering’s H1012) the input ground plane must be separated from the output ground
plane by either a physical separation or a void under either section. Good grounding requires taking
precautions to minimize inductance levels in the interconnections. Keeping ground returns short,
signal loop areas small, and power inputs bypassed to the signal return, will significantly reduce
radiation levels. See Figure 6 on page 6.
0.10 inches minimum separation
TD+
TD-
TDC
CMT
TX-
TX+
Magnetics Module
RD+
RD-
RDC
Void or separate
chassis plane
RXC
RX-
RX+
Ground plane
Figure 6. Ground and Power Connections for the Magnetics Module
Use the following guidelines to help reduce circuit inductance in both back planes and
motherboards.
• Route traces over a continuous ground plane with no interruptions. If there are vacant areas on
a ground or power plane, avoid routing signal conductors over the vacant area; routing signals
over such areas increases inductance and radiation levels.
• Separate noisy logic grounds from analog signal grounds to reduce coupling. Noisy logic
grounds can sometimes affect sensitive DC subsystems such as analog to digital conversion,
operational amplifiers, etc. All ground vias should be connected to every ground plane and
every power via should be connected to all power planes at equal potential. This helps reduce
circuit inductance. Physically locate grounds to minimize the loop area between a signal path
and its return path.
• Rise and fall times should be as slow as possible. Signals with fast rise and fall times contain
many high-frequency harmonics which can radiate significantly.
6
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
• The most sensitive signal returns closest to the chassis ground should be connected together.
This will result in a smaller loop area and reduce the likelihood of cross-talk. The effect of
different configurations on the amount of cross-talk can be studied using electronics modeling
software.
5.0
Terminating Unused Connections
For Ethernet designs, it is common practice to terminate unused connections on the RJ-45
connector and the magnetics line interface module to ground. Depending on the overall shielding
and grounding design, this may be done to the chassis ground, signal ground, or termination plane.
Care must be taken when using various grounding methods to insure that emission requirements
are met.
The method most often implemented is called the “Bob Smith” termination. This method uses a
floating termination plane that is cut out of a power plane. The floating plane acts as a capacitance
plate with the adjacent plane. The signals can be routed through 75 Ω resistors to the plane and
stray energy on unused pins are dumped to the plane.
The termination plane capacitance should equal a minimum value of 1500 pF. This helps reduce the
amount of cross-talk on the differential pairs (TDP/TDN and RDP/RDN) from the unused pairs of
the RJ-45. Pads may be placed for an additional capacitance to chassis ground, which may be
required due to failure of electrical fast transient testing. See Figure 6.
TDP
N/C
TDN
RDP
RJ-45
RDN
Magnetics Module
Termination plane
Additional capacitance that may
need to be added for EFT testing
Figure 7. Terminating Unused Connections on the RJ-45 Connector
Application Note (AP-399)
7
82559 Printed Circuit Board (PCB) Design
6.0
196-pin Ball Grid Array
The 196-pin Ball Grid Array (BGA) packaging was chosen for the 82559 to provide the highestperformance package. The 196 BGA enables the 82559 to provide a smaller footprint to reduce the
impact of LAN-on-motherboard designs. The result is a considerably smaller finished design size
with shorter electrical path lengths. The thin profile and smaller footprint make the 82559 an
attractive option when board space is a major concern, such as CardBus and LAN-on-notebook
designs.
The mechanical dimensions for the 15 mm2 package is shown in Figure 8.
15.00
0.20
15.00±0.20
Pin #1
Corner
13.00±0.25
Pin #1 Corner
10.57 Ref
0.60
0.40
14 12 10 8 6 4
2
13 11 9 7 5 3 1
A
B
C
D
E
F
G
H
I
J
K
L
M
N
P
13.00
±0.25
15.00
±0.20
1.00 Ref
45 Chamfer
Pin #1 I.D.
4 Places
1.0 Dia.
Top View
1.56±0.19
0.85
0.40±0.10
0.36±0.04
1.00 Ref
1.0
3 Places
1.00
Bottom View
196 Solder Balls
30
Seating Plane
Side View
A5829-01
NOTE: All dimensions are in millimeters.
Figure 8. 196-pin Ball Grade Array Mechanical Specifications
8
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
7.0
Designing Boards for the 196-pin BGA
Optimization for manufacturing yields is one of the greatest challenges for designers using ball
grid array packaging. Take care when selecting a pad criteria. Your printed circuit board supplier
should be able to consult with you on the methodology that is most appropriate. As a general rule,
most BGA packages use Solder Mask Defined (SMD) pads. PCB pad size will usually track close
to the package pad size to balance stresses during thermal cycling. Additional manufacturing tradeoffs may be required.
Designing for manufacturability is a critical consideration in maximizing yields using the 82559’s
196-pin BGA package. The assembly process heavily relies on the design of the surface mount
pads. Pad design methods that meet the needs of larger package types may not meet the
requirements of a BGA package. Overall, the design requires an array of round pads to provide the
mounting surface.
At first glance, the easiest method is to use the mounting pads that contain the vias. Unfortunately,
the mounting pads must be isolated from any vias plated through holes (PTHs). This prevents the
solder balls from leeching into the vias. Therefore, a connection from the PTH interstitial to the
mounting pads is used.
Dimensional control of the pad is critical to achieving high yields in assembly. The designer will
need to perform a comparison of the two methods, Solder Mask Defined (SMD) and Non-SMD (or
copper defined), for the purpose of delimiting the pad area. Non-SMD is most commonly used in
circuit design prior to the advent of BGA packaging. See Figure 9
Figure 9. Pad Delimitation Options
7.1
Solder Mask Defined (SMD) Pad
The SMD pad method uses the solder mask to define the usable pad. The copper for the pad area is
usually larger than the desired solderable area. The solder mask provides a smaller opening
diameter which limits the usable area to the desired size. The advantages to this method are:
• The solder mask is a photographically controlled instead of being at the mercy of the etch
process.
• The solder mask enhances copper adhesion by lying over the top of the pad surface.
Application Note (AP-399)
9
82559 Printed Circuit Board (PCB) Design
7.2
Non-Solder Mask (Copper) Defined Pad
The non-solder mask (or copper) defined pad has a solder mask opening larger than the copper
area. With this method, the pad periphery is left under the control of the etching process. As
expected, this method is generally not as accurate as the solder mask photo image control described
above. Although pad size varies more than with the SMD method, the pads can be made smaller for
the same ball area. This allows additional line routing space between pads. Pattern registration is
also more accurate with this method. This may be an advantage to vision systems since registration
on copper reference points will give the exact location of the site. Relying on the solder mask can
cause miscues because of variances in the site location relative to vision reference points.
7.3
196-pin BGA Routing and Pad Size
The 196-pin BGA package is more dense than normal BGA packages and provides additional
challenges for trace routing. With the 82559 many of these issues are handled by considered die
layout. The routing signals are carefully placed in the periphery to minimize routing congestion.
Signals are also grouped by function to minimize any need to route digital and analog signals
together.
Figure 10 shows the relational groupings. The box outline contains the PCI signal group. These
signals can easily be routed to the PCI connector without interfering with the analog routing area.
This can be observed in actual practice on a sample network card layout provided in Appendix A.
One of the primarily design goals in developing the 82559 was to reduce the cost of 10/100 Mbps
Ethernet connections. Therefore, power, die, and real estate requirements were achieved without
severely impacting layout complexity.
NC
SERR#
VCCPP
IDSEL
AD25
PME#
VCCPP
AD30
ALTRST
#
SMBCK
VCCPT
LILED
TEST
NC
AD22
AD23
VSSPP
AD24
AD26
AD27
VSSPP
AD31
ISOLAT
E#
SMBALR
T#
SPEEDL
ED
TO
RBIAS10
0
RBIAS10
AD21
RST#
REQ#
CBE#3
CSTSC
HG
AD28
AD29
CLKRU
N#
SMBD
VSSPT
ACTLED
VREF
TDP
TDN
AD18
AD19
AD20
VSS
VSS
VSS
VSS
VSS
NC
NC
VSS
TI
TEXEC
TCK
VCCPP
VSSPP
AD17
VSS
VSS
VSS
VSS
VSS
VSS
VSS
VSS
VCC
RDP
RDN
IRDY#
FRAME#
CBE#2
VSS
VSS
VSS
VSS
VSS
VSS
VSS
VSS
FLD2
FLD1
FLD0
CLK
VIO
TRDY#
NC
VCC
VCC
VSS
VSS
VSS
VSS
VSS
FLD3
VCCPL
VSSPL
STOP#
INTA#
DEVSEL
#
NC
VCC
VCC
VCC
VCC
VSS
VSS
VSS
FLD6
FLD5
FLD4
PAR
PERR#
GNT#
NC
VCC
VCC
VCC
VCC
VCC
VCC
VCC
FLA1
FLA0
FLD7
AD16
VSSPP
VCCPP
VCC
VCC
VCC
VCC
VCC
VCC
VCC
VCC
VSSPL
VCCPL
FLA2
AD14
AD15
CBE#1
VCC
VCC
VSS
NC
NC
VCC
VCC
VSS
FLA5
FLA4
FLA3
AD11
AD12
AD13
CBE#0
AD5
VSSPP
AD1
FLOE#
FLWE#
FLA15/
EESK
FLA12
FLA11
FLA7
FLA6
VSSPP
AD10
AD9
AD7
AD4
VCCPP
AD0
VCCPL
FLCS#
FLA14/
EEDO
X1
VSSPL
FLA10
FLA8
FLA16
FLA13/
EEDI
X2
VCCPL
FLA9
NC
NC
VCCPP
AD8
AD6
AD3
AD2
EECS
VSSPL
Figure 10. 82559 Ball Pattern
Table 1 summarizes general design rules for design provided in Appendix A.
10
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
Table 1.
82559 General Design Rules
Pad Information
Drill
Pads
Anti-pads
BGA pads
Not applicable
0.018 inch
Not applicable
BGA vias
0.010 inch
0.020 inch
0.032 inch
Standard vias
0.010 inch
0.032 inch
0.044 inch
NOTE: 82559 Micro BGA Pattern:
Number of balls (pins)
= 196
Ball pitch
= 1 mm (0.0394 inch)
Traces
= 0.006 inch
Trace spacing
= 0.006 inch
7.3.1
Top Layer Routing
Figure 11 shows the top side routing paths for the signals in the reference layout. (The complete
layout is contained in Appendix A.) In this diagram 6 mil traces are used to bring the signals from
the 18 mil ball pads out to 20 mil via pads. The vias use a 10 mil drill though the 20 mil pad.
Figure 11. 82559 Top Layer Routing
Application Note (AP-399)
11
82559 Printed Circuit Board (PCB) Design
7.3.2
Note:
Sensitive analog signals are routed completely on the top layer without the use of vias. This allows
tight control of signal integrity and removes any impedance inconsistencies due to layer changes.
Note:
The power plane connections use the top side planes to minimize the number of vias required. One
via per power connection would be optimal; however, this is almost impossible to achieve due to
the tight grid internal to the device.
Bottom Layer Routing
Figure 12 shows the bottom side routing paths from the vias. As mentioned previously, an attempt
to limit these signals was made. These signals have a higher tolerance for impedance
incongruences.
Figure 12. 82559 Bottom Layer Routing
7.3.3
Analog Signal Routing
The analog signals from the 82559 to the magnetics module are the most critical routing path. The
second most critical path from the magnetics module to the RJ-45. Controlling signal path
anomalies such as impedance, cross-talk, and EMI will increase performance. Analog signals from
the 82559’s PHY unit should run to the line interface components, not through any vias. In addition
to this restriction, these signals should be routed avoiding possible interference from neighboring
signals.
Generally, differential pairs (for example, TDP/TDN and RDP/RDN) should be routed prior to
starting any other layout. This ensures that a reasonable keep-out zone for other signals can be
maintained. Figure 13 shows the route of these signals in the reference layout.
12
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
Trace spacing, trace length, as well as avoidance of digital signals was maintained. In this example,
a single small surface mount termination resistor is placed directly across the signal pairs to help
avoid reflections from trace bends or stubs.
Single termination allows optimal route of
differential transmit and receive pairs.
Figure 13. 82559 Analog Signal Routing
Application Note (AP-399)
13
82559 Printed Circuit Board (PCB) Design
14
Application Note (AP-399)
82559 Printed Circuit Board (PCB) Design
Appendix A 82559 Layout Diagrams
This appendix contains the following diagrams:
•
•
•
•
•
Sample Network Card Layer 1 (Top Side Layout)
Sample Network Card Layer 2 (Ground Plane Layout)
Sample Network Card Layer 3 (Power Plane Layout)
Sample Network Card Layer 4 (Backside Layout)
Sample Network Card Fabrication
Application Note (AP-399)
15
Sample Network Card Layout Top Side View
Split Ground Under Magnetics Module
Signal Ground
Chassis Ground Plane
Sample Network Card Layout Layer 2 (Ground Plane)
Plane
Termination Plane
Sample Network Card Layout Layer 3 (Power Plane)
Note: This layout uses a split power plane to route one of three voltage sources to a voltage regulator. The
82559 is sourced from the output of the voltage regulator.
PCI Signal Routing
Sample Network Card Layout Layer 4 (Backside)
Sample Network Card Fabrication Drawing