Intel IXP45X, IXP46X manual Soft Fusible Features, Signal Type Definitions, Symbol Description

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General Hardware Design Considerations—Intel®IXP45X and Intel® IXP46X Product Line of Network Processors

3.0General Hardware Design Considerations

	This chapter contains information for implementing and interfacing to major hardware
	blocks of the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors.
	Such blocks include DDR SDRAM, Flash, SRAM, Ethernet PHYs, UART and most other
	peripherals interfaces. Signal definition tables list resistor recommendations for pull-
	ups and pull-downs.
	Features disabled by a specific part number, do not require pull-ups or pull-downs.
	Therefore, all pins can be left unconnected. Features enabled by a specific part number
	and required to be Soft Fuse-disabled, only require pull-ups or pull-downs in the clock-
	input signals. Other conditions may require pull-up or pull-down resistors for
	configuration purposes at power on or reset. Likewise, open-collector outputs must be
	pulled-high.
Warning:	The IXP45X/IXP46X network processors’ I/O pins are 3.3 V only, except for DDR
	SDRAM which is 2.5 V. None of the I/Os are 5-V tolerant.
	Table 2 gives the legend for interpreting the Type field used in this chapter’s signal-
	definition tables.
Table 2.	Signal Type Definitions

	Symbol		Description

	I		Input pin only

	O		Output pin only

	I/O		Pin can be either an input or output

	OD		Open-drain pin

	TRI		Tri-State pin

	PWR		Power pin

	GND		Ground pin

3.1Soft Fusible Features

Soft Fuse Enable/Disable is a method to enable or disable features in hardware, virtually disconnecting the hardware modules from the processor.

Some of the features offered in the IXP45X/IXP46X product line can be Soft Fuse Enabled/Disabled during boot. It is recommended that if a feature is not used in the design, the feature be Soft disabled. This helps reduce power and maintain the part running at a cooler temperature. When Soft Fuse Disabled, a pull-up resistor must be connected to each clock input pins of the disabled feature interface. All other signals can be left unconnected.

Soft Fuse Enable/Disable can be done by writing to EXP_UNIT_FUSE_RESET register, for more information refer to the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors Developer’s Manual and review the register description.

	Intel® IXP45X and Intel® IXP46X Product Line of Network Processors
February 2007	HDD
Document Number: 305261; Revision: 004	17

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Contents February Hardware Design GuidelinesHDD Contents 12.1 Figures Tables Control Group Topology Transmission Line CharacteristicsDate Revision Description Revision HistoryHDD Chapter Name Description Content OverviewTitle Document # Related DocumentationTerm Explanation OverviewList of Acronyms and Abbreviations Smii Intel IXP465 Component Block Diagram Dslam Typical ApplicationsSystem Memory Map System Architecture DescriptionIntel IXP465 Example System Block Diagram Symbol Description Soft Fusible FeaturesSignal Type Definitions Soft Fusible Features Signal InterfaceDDR-266 Sdram Interface DDR Sdram Interface Pin Description Sheet 1Ddriwen DDR Sdram Interface Pin Description Sheet 2Ddrircveninn DdrircompDDR Sdram Initialization Expansion BusDDR Sdram Memory Interface Input Pull Name Recommendations Output Down Reset Configuration StrapsExpansion Bus Signal Recommendations Name Function Description Boot/Reset Strapping Configuration Sheet 14 16-Bit Device Interface Boot/Reset Strapping Configuration Sheet 23 8-Bit Device Interface 5 32-Bit Device Interface Bit Device 16/32-Bit Device Interface Byte Enable Flash Interface Example Flash InterfaceDesign Notes Uart InterfaceSram Interface Name Input Pull Recommendations Output Down Uart Signal RecommendationsUart Interface Example MII/SMII InterfaceMII NPE B Signal Recommendations Sheet 1 Signal Interface MIIMII NPE a Signal Recommendations MII NPE C Signal Recommendations MII NPE B Signal Recommendations Sheet 2NPE A,B,C MAC Management Signal Recommendations NPE A,B,CDevice Connection, MII Smii Signal Recommendations NPE A, B, C Signal Interface, SmiiDevice Connection, Smii Gpio InterfaceGpio Signal Recommendations Device Connection I2C Signal RecommendationsI2C Interface I2C Eeprom Interface Example USB InterfaceUSB Host/Device Signal Recommendations Host Device USB Device Interface Example Utopia Level 2 InterfaceUtopia Signal Recommendations Utopia Interface Example HSS InterfaceHSSTXDATA0 High-Speed, Serial InterfaceHSSTXCLK0 HSSRXDATA0HSSTXCLK1 HSSTXDATA1HSSRXDATA1 HSSRXCLK1HSS Interface Example SSP InterfaceSynchronous Serial Peripheral Port Interface Input Pull Name Outpu Recommendations Down PCI InterfacePCI Controller Sheet 1 PCI Controller Sheet 2 PCI Interface Block DiagramPCI Interface Supporting 5 V PCI InterfacePCI Host/Option Interface Pin Description Sheet 1 PCI Option InterfacePCI Host/Option Interface Pin Description Sheet 2 PCI Host/Option Interface Pin Description Sheet 3 Jtag InterfaceClock Signals Clock SignalsInput System Clock Clock OscillatorName Nominal Description Voltage PowerPower Interface Sheet 1 Reset Timing Power SequenceDe-Coupling Capacitance Recommendations VCC De-CouplingHDD HDD PCB Overview Component PlacementGeneral Recommendations Component SelectionStack-Up Selection Component Placement on a PCBControlled-impedance traces Low-impedance power distribution Layer Stackup General Layout Guidelines General Layout and Routing GuideGeneral Component Spacing Signal Changing Reference PlanesGood Design Practice for VIA Hole Placement Pad-to-Pad Clearance of Passive Components to a PGA or BGA Clock Signal ConsiderationsUSB Considerations Smii Signal ConsiderationsMII Signal Considerations EMI-Design Considerations Cross-TalkTrace Impedance Power and Ground PlaneHDD Topology Electrical Interface@33 MHz @66 MHzParameter Routing Guidelines Clock DistributionPCI Address/Data Routing Guidelines PCI Clock Routing Guidelines Trace Length LimitsRouting Guidelines Signal LoadingGroup Signal Name Description No of Single Ended Signals DDR Signal GroupsIntroduction DDRIDQS40DDR Sdram HDD Clock Banks Memory Size Supported Memory ConfigurationsVTT VTT Terminating Circuitry Selecting VTT Power SupplyDdrmclk DDR Command and Control Setup and Hold ValuesSymbol Parameter Min Max Units DDR Data to DQS Read Timing Parameters DDR Data to DQS Write Timing Parameters DDR-Data-to-DQS-Write Timing ParametersPrinted Circuit Board Layer Stackup Printed Circuit Board Layer Stackup Printed Circuit Board Controlled ImpedancePrinted Circuit Board Controlled Impedance Timing Relationships Signal Group Absolute Minimum Absolute Maximum LengthTiming Relationships Clock Group Resistive Compensation Register RcompData, Command, and Control Group Routing Guidelines Clock Signal Group Routing GuidelinesParameter Definition DDRIBA10, DDRIRASN, DDRICASN, DdriwenSimulation Results Clock Group Topology Transmission Line CharacteristicsClock Group Transmission Line LengthDDR Clock Topology Two-Bank x16 Devices DDR Clock Simulation Results Two-Bank x16 Devices Data GroupData 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 CharacteristicsDDR RAS Simulation Results Two-Bank x16 Devices Command Group Topology Transmission Line Characteristics Command GroupDDR 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 RcvenoutDDR RCVENIN/RCVENOUT Simulation Results Rseries = 0 Ω DDR RCVENIN/RCVENOUT Simulation Results Rseries = 60 Ω 108