Printed Circuit Board Controlled Impedance | Intel IXP45X, IXP46X

DDR-SDRAM—Intel®IXP45X and Intel® IXP46X Product Line of Network Processors

Figure 35. Printed Circuit Board Layer Stackup

7.1.4Printed Circuit Board Controlled Impedance

Controlled impedance for each layer of the IXDP465 platform x16 Processor Module is necessary to provide proper matching from driver to receiver(s) for improved signal integrity and higher reliability in the signal analysis results obtained through simulation. As indicated in Figure 36 on page 86, Layers 4, 6, 7, and 9 are impedance controlled for clock routing (60-Ω, single-ended’ 120-Ω, differential) as well as all other DDR signals (50 Ω, single-ended). Layers 3 and 10 are also impedance controlled for 50-Ω, single-ended traces.

	Intel® IXP45X and Intel® IXP46X Product Line of Network Processors
February 2007	HDD
Document Number: 305261, Revision: 004	85

Image 85

Intel IXP45X, IXP46X manual Printed Circuit Board Controlled Impedance, Printed Circuit Board Layer Stackup

Contents

February Hardware Design Guidelines HDD Contents 12.1 Figures Tables Control Group Topology Transmission Line Characteristics Date Revision Description Revision History HDD Chapter Name Description Content Overview Title Document # Related Documentation List of Acronyms and Abbreviations OverviewTerm Explanation Smii Intel IXP465 Component Block Diagram Dslam Typical Applications System Memory Map System Architecture Description Intel IXP465 Example System Block Diagram Signal Type Definitions Soft Fusible FeaturesSymbol Description Soft Fusible Features Signal InterfaceDDR-266 Sdram Interface DDR Sdram Interface Pin Description Sheet 1 Ddriwen DDR Sdram Interface Pin Description Sheet 2Ddrircveninn Ddrircomp DDR Sdram Memory Interface Expansion BusDDR Sdram Initialization Expansion Bus Signal Recommendations Reset Configuration StrapsInput Pull Name Recommendations Output Down Name Function Description Boot/Reset Strapping Configuration Sheet 1 3 8-Bit Device Interface Boot/Reset Strapping Configuration Sheet 24 16-Bit Device Interface 5 32-Bit Device Interface Bit Device 16/32-Bit Device Interface Byte Enable Flash Interface Example Flash Interface Sram Interface Uart InterfaceDesign Notes Name Input Pull Recommendations Output Down Uart Signal Recommendations Uart Interface Example MII/SMII Interface MII NPE a Signal Recommendations Signal Interface MIIMII NPE B Signal Recommendations Sheet 1 MII NPE C Signal Recommendations MII NPE B Signal Recommendations Sheet 2 Device Connection, MII MAC Management Signal Recommendations NPE A,B,CNPE A,B,C Smii Signal Recommendations NPE A, B, C Signal Interface, Smii Device Connection, Smii Gpio Interface Gpio Signal Recommendations I2C Interface I2C Signal RecommendationsDevice Connection I2C Eeprom Interface Example USB Interface USB Host/Device Signal Recommendations Host Device USB Device Interface Example Utopia Level 2 Interface Utopia Signal Recommendations Utopia Interface Example HSS Interface HSSTXDATA0 High-Speed, Serial InterfaceHSSTXCLK0 HSSRXDATA0 HSSTXCLK1 HSSTXDATA1HSSRXDATA1 HSSRXCLK1 HSS Interface Example SSP Interface Synchronous Serial Peripheral Port Interface PCI Controller Sheet 1 PCI InterfaceInput Pull Name Outpu Recommendations Down PCI Controller Sheet 2 PCI Interface Block Diagram PCI Interface Supporting 5 V PCI Interface PCI Host/Option Interface Pin Description Sheet 1 PCI Option Interface PCI Host/Option Interface Pin Description Sheet 2 PCI Host/Option Interface Pin Description Sheet 3 Jtag Interface Clock Signals Clock SignalsInput System Clock Clock Oscillator Power Interface Sheet 1 PowerName Nominal Description Voltage Reset Timing Power SequenceDe-Coupling Capacitance Recommendations VCC De-Coupling HDD HDD PCB Overview Component PlacementGeneral Recommendations Component Selection Stack-Up Selection Component Placement on a PCB Controlled-impedance traces Low-impedance power distribution Layer Stackup General Layout Guidelines General Layout and Routing Guide General Component Spacing Signal Changing Reference Planes Good Design Practice for VIA Hole Placement Pad-to-Pad Clearance of Passive Components to a PGA or BGA Clock Signal Considerations MII Signal Considerations Smii Signal ConsiderationsUSB Considerations EMI-Design Considerations Cross-Talk Trace Impedance Power and Ground Plane HDD Topology Electrical Interface@33 MHz @66 MHz PCI Address/Data Routing Guidelines Clock DistributionParameter Routing Guidelines PCI Clock Routing Guidelines Trace Length Limits Routing Guidelines Signal Loading Group Signal Name Description No of Single Ended Signals DDR Signal GroupsIntroduction DDRIDQS40 DDR Sdram HDD Clock Banks Memory Size Supported Memory Configurations VTT VTT Terminating Circuitry Selecting VTT Power Supply Symbol Parameter Min Max Units DDR Command and Control Setup and Hold ValuesDdrmclk DDR Data to DQS Read Timing Parameters DDR Data to DQS Write Timing Parameters DDR-Data-to-DQS-Write Timing Parameters Printed Circuit Board Layer Stackup Printed Circuit Board Layer Stackup Printed Circuit Board Controlled Impedance Printed Circuit Board Controlled Impedance Timing Relationships Signal Group Absolute Minimum Absolute Maximum LengthTiming Relationships Clock Group Resistive Compensation Register Rcomp Data, Command, and Control Group Routing Guidelines Clock Signal Group Routing GuidelinesParameter Definition DDRIBA10, DDRIRASN, DDRICASN, Ddriwen Simulation Results Clock Group Topology Transmission Line CharacteristicsClock Group Transmission Line Length DDR Clock Topology Two-Bank x16 Devices DDR Clock Simulation Results Two-Bank x16 Devices Data Group Data Group Topology Transmission Line Characteristics DDR Data Topology Two-Bank x16 Devices DDR Data Write Simulation Results Two-Bank x16 Devices HDD HDD Control Group Control Group Topology Transmission Line Characteristics DDR RAS Simulation Results Two-Bank x16 Devices Command Group Topology Transmission Line Characteristics Command Group DDR Command MA3 Topology Two-Bank x16 Devices DDR Address Simulation Results Two-Bank x16 Devices DDR Command RAS Topology Two-Bank x16 Devices 104 DDR RCVENIN/RCVENOUT Topology Rcvenin and Rcvenout DDR RCVENIN/RCVENOUT Simulation Results Rseries = 0 Ω DDR RCVENIN/RCVENOUT Simulation Results Rseries = 60 Ω 108