SNLS450A January   2014  – June 2015 DS125DF111

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration And Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Device Data Path Operation
        1. 7.3.1.1 Input Channel Equalization
        2. 7.3.1.2 Clock and Data Recovery
        3. 7.3.1.3 PRBS Pattern Generator
        4. 7.3.1.4 Datapath Multiplexer and Output Driver
        5. 7.3.1.5 Reference Clock
        6. 7.3.1.6 Control Pins
          1. 7.3.1.6.1 Pin Mode Limitation
        7. 7.3.1.7 Eye Opening Monitor
    4. 7.4 Device Functional Modes
      1. 7.4.1 Control Pin Mode
      2. 7.4.2 SMBus Master Mode and SMBus Slave Mode
    5. 7.5 Programming
      1. 7.5.1 SMBus Interface
        1. 7.5.1.1  Address Lines
        2. 7.5.1.2  Device Configuration in SMBus Slave Mode
        3. 7.5.1.3  Bit Fields in the Register Set
        4. 7.5.1.4  Writing To and Reading from the Control/Shared Registers
        5. 7.5.1.5  SMBus Strap Observation
        6. 7.5.1.6  Interrupt Channel Flag Bits
        7. 7.5.1.7  Control/Shared Register Reset
        8. 7.5.1.8  Device Revision and Device ID
        9. 7.5.1.9  Channel Select Register
        10. 7.5.1.10 Resetting Individual Channels of the Retimer
        11. 7.5.1.11 Rate and Subrate Setting
        12. 7.5.1.12 Overriding the CTLE Boost Setting
        13. 7.5.1.13 Overriding the Output Multiplexer
        14. 7.5.1.14 Overriding the VCO Divider Selection
        15. 7.5.1.15 Using the Internal Eye Opening Monitor
        16. 7.5.1.16 Overriding the DFE Tap Weights and Polarities
        17. 7.5.1.17 Enabling Slow Rise/Fall Time on the Output Driver
        18. 7.5.1.18 Using the PRBS Generator
        19. 7.5.1.19 Inverting the Output Polarity
        20. 7.5.1.20 Figure of Merit Adaption
        21. 7.5.1.21 Setting the Rate and Subrate for Lock Acquisition
        22. 7.5.1.22 Setting the Adaption/Lock Mode
        23. 7.5.1.23 Initiating Adaption
        24. 7.5.1.24 Overriding the CTLE Settings Used for CTLE Adaption
        25. 7.5.1.25 Setting the Output Differential Voltage
        26. 7.5.1.26 Setting the Output De-Emphasis Setting
        27. 7.5.1.27 CTLE Setting for Divide by 4 and Divide by 8 VCO Ranges
    6. 7.6 Register Maps
      1. 7.6.1 Reading To and Writing from the Channel Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
        1. 8.2.3.1 SFF-8431 Testing
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10 Layout

10.1 Layout Guidelines

The high speed inputs and outputs have been optimized to work with interconnects using a controlled differential impedance of 100Ω. Vias should be used sparingly and must be placed symmetrically for each side of a given differential pair. Whenever differential vias are used the layout must also provide for a low inductance path for the return currents as well. Route the differential signals away from other signals and noise sources on the printed circuit board.

Figure 13 highlights good high-speed layout techniques.

  1. Maintain differential pair symmetry to minimize any signal conversion to common mode.
  2. Isolate Tx - Rx differential pairs with a minimum of 5x inter-pair to intra-pair spacing ratio.
  3. Decoupling should be placed as close as possible to the DS125DF111
  4. Use differential vias which incorporate reference plane current returns and relief to minimize impedance disruption.
  5. Use a back-drill technique to minimize via stubs.
  6. Keep Loop Filter capacitors as close as possible to the DS125DF111.

10.2 Layout Example

DS125DF111 SimplifiedLayout_111.gifFigure 13. DS125DF111 Typical Layout