Hayes Microcomputer Products RCV56HCF Ground Planes, Crystal Circuit, 7 VCL1 and Vref Circuit

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RCV56HCF PCI/CardBus Modem Designer’s Guide

4.1.5 Ground Planes

1.In a 2-layer design, provide digital and analog ground plane areas in all unused space around and under digital and analog circuit components (exclusive of the DAA), respective, on both sides of the board, and connect them such a manner as to avoid small islands. Connect each ground plane area to like ground plane areas on the same side at several points and to like ground plane areas on the opposite side through the board at several points. Connect all modem DGND pins to the digital ground plane area and AGND pins to the analog ground plane area. Typically, separate the collective digital ground plane area from the collective analog ground plane area by a fairly straight gap. There should be no inroads of digital ground plane area extending into the analog ground plane area or visa versa.

2.In a 4-layer design, provide separate digital and analog ground planes covering the corresponding digital and analog circuits (exclusive of the DAA), respectively. Connect all modem DGND pins to the digital ground plane and AGND pins to the analog ground plane. Typically, separate the digital ground plane from the analog ground plane by a fairly straight gap.

3.In a design which needs EMI filtering, define an additional “chassis” section adjacent to the bracket end of a plug-in card. Most EMI components (usually ferrite beads/capacitor combinations) can be positioned in this section. Fill the unused space with a chassis ground plane, and connect it to the metal card bracket and any connector shields/grounds.

4.Keep the current paths of separate board functions isolated, thereby reducing the current's travel distance. Separate board functions are: host interface, display, digital (SRAM, EPROM, modem), and DAA. Power and ground for each of these functions should be separate islands connected together at the power and ground source points only.

5.Connect grounds together at only one point, if possible, using a ferrite bead. Allow other points for grounds to be connected together if necessary for EMI suppression.

6.Keep all ground traces as wide as possible, at least 25 mil to 50 mil.

7.Keep the traces connecting all decoupling capacitors to power and ground at their respective ICs as short and as direct (i.e., not going through vias) as possible.

4.1.6 Crystal Circuit

1.Keep all traces and component leads connected to crystal input and output pins (i.e., XTLI and XTLO) short in order to reduce induced noise levels and minimize any stray capacitance that could affect the crystal oscillator. Keep the XTLO trace extremely short with no bends greater than 45 degrees and containing no vias since the XTLO pin is connected to a fast rise time, high current driver.

2.Where a ground plane is not available, such as in a 2-layer design, tie the crystal capacitors ground paths using separate short traces (as wide as possible) with minimum angles and vias directly to the corresponding device digital ground pin nearest the crystal pins.

3.Connect crystal cases(s) to ground (if applicable).

4.Place a 100-ohm (typical) resistor between the XTLO pin and the crystal/capacitor node.

5.Connect crystal capacitor ground connections directly to GND pin on the modem device. Do not use common ground plane or ground trace to route the capacitor GND pin to the corresponding modem GND pin.

4.1.7 VC_L1 and VREF Circuit

1.Provide extremely short, independent paths for VC_L1 and VREF capacitor connections.

a)Route the connection from the plus terminal of the 10 μF VC_L1 capacitor and one terminal of the 0.1 μF VC_L1 capacitor to the modem device VC_L1 pin (pin 24) using a single trace isolated from the trace to the VC_L1 pin from the VREF capacitors (see step d).

b)Route the connection from the negative terminal of the 10 μF VC_L1 capacitor and the other terminal of a the 0.1 μF VC_L1 capacitor to a ferrite bead. The bead should typically have characteristics such as: impedance = 70 Ω at a frequency of 100 MHz , rated current = 200 mA, and maximum resistance = 0.5 Ω. Connect the other bead terminal to the AGND pin (pin 34) with a single trace.

c)Route the connection from the plus terminal of the 10 μF VREF capacitor and one terminal of the 0.1 μF VREF capacitor to the modem device VREF pin (pin 25) with a single trace.

d)Route the connection from the negative terminal of 10 μF VREF capacitor and the other terminal of the 0.1 μF VREF capacitor to the modem device VC_L1 pin (pin 24) with a single trace isolated from the trace to the VC_L1 pin from the VC_L1 capacitors (see step a).

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ROCKWELL PROPRIETARY INFORMATION

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Contents RCV56HCF RCV56HCF PCI/CardBus Modem Designer’s Guide Table of Contents Command SET Rockwell Proprietary Information List of Figures List of Tables Features SummaryRCV56HCF PCI/CardBus Modem Designer’s Guide Modem Models and Functions MarketingModel Number1 FdspPC Software RCV56HCF Hardware Configuration Block Diagram Data Pump BUS General Description Technical OverviewOperating Modes Downloadable Modem Data Pump Firmware Host-Controlled Modem SoftwareHardware Interfaces RCV56HCF PCI/CardBus Modem Designer’s Guide Typical Audio Signal Interface U.S Typical Signal Routing Voice Mode Relay Positions VoiceView Mode+VLS= VOICE# CIDL1#This page is intentionally blank Data Mode Establishing Data Modem ConnectionsError Correction and Data Compression VOICE/AUDIO ModeMNP 10EC Enhanced Cellular Connection FAX Class 1 OperationFULL-DUPLEX Speakerphone Fdsp Mode HOST-BASED Dsvd ModeVoiceview Diagnostics LOW Power Sleep ModeCaller ID World Class Country SupportHardware Signal Pins and Definitions Hardware InterfaceBUS Interface Tqfp 11229RCV56HCF MDP PIN Tqfp R6776Bus Interface 176-Pin Tqfp Hardware Interface Signals Bus Interface 176-Pin Tqfp Pin Signals Pin Signal Label Type1 Interface DEVSEL# System Bus Interface Pin Signal DefinitionsPCI BUS Interface Bus Interface Pin Signal Definitions Cont’d Serial Eeprom Interface NMC93C56 or EquivalentDAA Interface ReservedMDP Interface Isdn Interface NON-ISDN Models Isdn Interface Isdn ModelsMDP 144-Pin Tqfp Hardware Interface Signals MDP 144-Pin Tqfp Pin Signals MDP Pin Signals 144-Pin Tqfp Pin Signal Label Interface3 Type1Pllgnd PLL MDP Pin Signal Definitions Overhead SignalsBIF to MDP Interface MDP to Siemens PSB2186 S/T InterfaceMDP Signal Definitions Contd Pllgnd Connection. Connect to AgndModem INTERCONNECT/NO Connect ELECTRICAL,SWITCHING,AND Environmental Characteristics Power and Maximum RatingsCurrent and Power Requirements Maximum RatingsPCI Bus DC Specifications for 3.3V Signaling PCI Bus AC Specifications for 3.3V SignalingSymbol Parameter Condition Min Max Units PCI BusParameter Symbol Min Typ Max Units Test Conditions MDP Digital Electrical Characteristics3 MDP 10. Analog Electrical Characteristics Name Type Characteristic ValueTELINL1 TXA1L1Interface Timing and Waveforms PCI Bus TimingSerial Eeprom Timing 11. Timing Serial Eeprom InterfaceSymbol Description Min Typ Max Units Test Conditions Read External Device Bus Timing12. Timing External Device Bus Interface WriteISDNCS# DRD# DD0-DD7 ISDNCS# DWR# DD0-DD7IOM-2 Interface 13. Timing IOM-2 InterfaceThis page is intentionally blank PC Board Layout Guidelines Component Placement General Principles Signal Routing Power Modem Pin Noise CharacteristicsDevice Function Noise Source Neutral Noise Sensitive MDP VDD, VAACrystal Circuit Ground Planes7 VCL1 and Vref Circuit CRYSTAL/OSCILLATOR Specifications Optional ConfigurationsOther Considerations Telephone and Local Handset InterfaceCrystal Specifications Surface Mount Characteristic ValueElectrical MechanicalCrystal Specifications Through Hole Package Dimensions Package Dimensions 144-Pin TqfpRCV56HCF PCI/CardBus Modem Designer’s Guide This page is intentionally blank PCI Configuration Registers Vendor ID FieldDevice ID Field Bit Offset 3124 2316 158 HexStatus Register Command RegisterBit Description Base Address Register Eeprom Configuration Data Serial Eeprom InterfaceEeprom Address Copied to CIS RAMCommand SET Command Set Summary Functional Use SortCommand Set Summary Functional Use Sort Cont’d Data CompressionVoice Commands Command Set Summary Alphanumeric Sort Command Set Summary Alphanumeric Sort Cont’d RCV56HCF PCI/CardBus Modem Designer’s Guide Inside Back Cover Regional Sales Offices
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