IBASE Technology ET976 Guida
COM EXPRESS
CARRIER BOARD
DESIGN GUIDE
Version 1.0
(January 2022)
ii COM Express® Carrier Board Design Guide
Disclaimer
IBASE reserves the right to make changes and improvements to this document without prior notice. Every effort has
been made to ensure the information in the document is correct; however, IBASE does not guarantee this document
is error-free. IBASE assumes no liability for incidental or consequential damages arising from misapplication or
inability to use the information contained herein, nor for any infringements of rights of third parties, which may result
from its use.
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COM Express® Carrier Board Design Guide ii
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TableofContents
Chapter 1 General Information ................................................................. 1
1.1ABOUT COM EXPRESS ........................................................................... 1
Chapter 2 COM Express Interfaces ............................................................... 2
2.1General Purpose PCIe Lanes .................................................................... 3
2.1.1Device Up / Device Down and PCIe Rx / Tx Coupling Capacitors ......... 3
2.1.2Schematic Examples .............................................................................. 4
2.1.3PCI Express Routing Considerations ..................................................... 7
2.2PEG (PCI Express Graphics) ..................................................................... 8
2.2.1Reference Schematics ......................................................................... 10
2.3Digital Display Interfaces ......................................................................... 11
2.3.1DisplayPort / HDMI / DVI .................................................................... 11
2.3.1.1Reference Schematic ......................................................................... 12
2.3.1.2Routing Considerations ...................................................................... 17
2.3.2SDVO ................................................................................................. 18
2.3.2.1Signal Definitions ............................................................................... 18
2.3.2.2Reference Schematics ....................................................................... 18
2.3.2.3Routing Considerations ...................................................................... 18
2.4LAN .......................................................................................................... 19
2.4.1Signal Definitions ............................................................................... 19
2.4.2Reference Schematics ....................................................................... 20
2.4.3Routing Considerations ...................................................................... 20
2.5USB Ports ................................................................................................ 21
2.5.1Signal Definitions ............................................................................... 21
2.5.2Reference Schematics ....................................................................... 22
2.5.3Routing Considerations ...................................................................... 22
2.6USB 3.0 .................................................................................................... 23
2.6.1Signal Definitions ............................................................................... 23
2.6.2Reference Schematics ....................................................................... 24
2.6.3Routing Considerations ...................................................................... 26
2.7SATA ........................................................................................................ 27
2.7.1Signal Definitions ............................................................................... 27
2.7.2Reference Schematic ......................................................................... 28
2.7.3Routing Considerations ...................................................................... 28
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2.8LVDS ........................................................................................................ 29
2.8.1Signal Definitions ............................................................................... 29
2.8.2Reference Schematics ....................................................................... 30
2.8.3Routing Considerations ...................................................................... 32
2.9Embedded DisplayPort (eDP) .................................................................. 33
2.9.1Signal Definitions ..................................................................................... 33
2.9.2Reference Schematics ............................................................................. 34
2.9.3Routing Considerations ............................................................................ 35
2.10VGA ......................................................................................................... 36
2.10.1Signal Definitions ............................................................................... 36
2.10.2VGA Reference Schematics .............................................................. 37
2.10.3Routing Considerations ...................................................................... 39
2.10.3.1RGB Analog Signals .................................................................... 39
2.10.3.2HSYNC and VSYNC Signals ....................................................... 39
2.10.3.3DDC Interface .............................................................................. 39
2.11Digital Audio Interfaces ............................................................................ 40
2.11.1Reference Schematics ....................................................................... 41
2.11.1.1High Definition Audio .......................................................................... 41
2.11.2Routing Considerations ...................................................................... 43
2.12LPC Bus – Low Pin Count Interface ........................................................ 44
2.12.1Signal Definition ................................................................................. 44
2.12.2LPC Bus Reference Schematics ........................................................ 45
2.12.2.1Super I/O ...................................................................................... 45
2.12.3Routing Considerations ...................................................................... 47
2.12.3.1General Signals ............................................................................ 47
2.13Serial Peripheral Interface Bus ................................................................ 48
2.13.1Signal Definition ................................................................................. 48
2.13.2SPI Reference Schematics ................................................................ 49
2.13.3Routing Considerations ...................................................................... 49
2.14General Purpose I2C Bus Interface ......................................................... 50
2.14.1Signal Definitions ............................................................................... 50
2.14.2Reference Schematics ....................................................................... 50
2.14.3Connectivity Considerations ............................................................... 5 0
2.15System Management Bus (SMBus) ......................................................... 51
2.15.1Signal Definitions ............................................................................... 52
2.15.2Routing Considerations ...................................................................... 52
COM Express® Carrier Board Design Guide
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2.16General Purpose Serial Interface ............................................................. 53
2.16.1Signal Definitions ............................................................................... 53
2.16.2Reference Schematics ....................................................................... 54
2.16.2.1 General Purpose Serial Port Example ................................................ 54
2.16.3Routing Considerations ...................................................................... 56
2.17CAN Interface .......................................................................................... 56
2.17.1Signal Definitions ............................................................................... 56
2.17.2Reference Schematics ....................................................................... 57
2.17.3Routing Considerations ...................................................................... 58
2.18Miscellaneous Signals ............................................................................. 59
2.18.1Speaker Output .................................................................................. 60
2.18.2RTC Battery Implementation .............................................................. 61
2.18.3Power Management Signals .............................................................. 62
2.18.4Watchdog Timer ................................................................................. 65
2.18.5General Purpose Input/Output (GPIO) ............................................... 65
2.18.6Fan Connector ................................................................................... 66
2.18.7Thermal Interface ............................................................................... 67
2.19PCI Bus .................................................................................................... 68
2.19.1Signal Definitions ............................................................................... 68
2.19.2Reference Schematics ....................................................................... 70
2.20IDE and CompactFlash (PATA) ............................................................... 72
2.20.1Signal Definitions ............................................................................... 72
Chapter 3 Power and Reset .......................................................................... 74
3.1ATX Style Power Control ......................................................................... 75
Chapter 4 Carrier Board PCB Layout Guidelines ....................................... 78
4.1General .................................................................................................... 79
4.2PCB Stack-ups ......................................................................................... 79
4.3Trace Impedance Considerations ............................................................ 82
Chapter 5 Mechanical Considerations ........................................................ 83
5.1Form Factors ............................................................................................ 83
5.2Heatspreader ........................................................................................... 84
5.3COM Express Carrier Board .................................... 錯誤! 尚未定義書籤。
5.4COM Express Module and Heatsink ........................ 錯誤! 尚未定義書籤。
vi COM Express® Carrier Board Design Guide
5.5 COM Express Connector (Tyco) .............................. 錯誤! 尚未定義書籤。
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General Information
COM Express® Carrier Board Design Guide 1
1
Chapter 1
General Information
This design guide provides suggestions on designing IBASE COM-Express products
including carrier boards and systems. For other carrier board schematic guidelines
please refer to the full specification in the PICMG® COM Express® Carrier Board
Design Guide.
This design guide is not a specification and should not be your sole reference. The
guide is intended for electronics engineers and PCB layout engineers involved in the
design of the COM Express Modules Carrier Boards. The schematic examples in
this document are believed to be correct, however, no guarantee is given. The
examples shown here have been taken from the designs that were already tested.
For any questions that you may have in the design of carrier boards, please contact
IBASE sales representatives or engineers in your area.
1.1 ABOUT COM EXPRESS
COM Express is a highly integrated computer module that is integrated with the
CPU, memory and I/O functions including USB, audio, graphics and Ethernet, which
signals are mapped to two high-density, low-profile connectors at the bottom of the
module.
COM Express uses a mezzanine concept, with a module inserted onto customized
base boards. The module and base boards can be both upgraded to newer versions
and to earlier-designed compatible versions. Common applications for COM Express
modules are in various applications in the field of IoT, industrial automation, military,
gaming, medical and transportation.
2 COM Express® Carrier Board Design Guide
Chapter 2
COM Express Interfaces
The information provided in this chapter includes:
General Purpose PCIe Lanes
PEG (PCI Express Graphics)
Digital Display Interfaces
LAN
USB Ports
USB 3.0
SATA
LVDS
Embedded DisplayPort (eDP)
VGA
Digital Audio Interfaces
LPC Bus – Low Pin Count Interface
Serial Peripheral Interface Bus
General Purpose I2C Bus Interface
System Management Bus (SMBus)
General Purpose Serial Interface
CAN Interface
Miscellaneous Signals
PCI Bus
IDE and CompactFlash (PATA)
COM Express® Carrier Board Design Guide 3
2.1 General Purpose PCIe Lanes
2.1.1 Device Up / Device Down and PCIe Rx / Tx Coupling Capacitors
Figure 1: PCIe Rx Coupling Capacitors
The coupling caps for the Module PCIe TX lines are to be on the Module, as indicated in the COM
Express specification.
4 COM Express® Carrier Board Design Guide
2.1.2 Schematic Examples
Figure 2: PCI Express x1 Slot Example
Altri manuali per ET976
1
Indice
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