SNLS448A January   2013  – October 2015 DS100RT410

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 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
      2. 7.3.2  Signal Detect
      3. 7.3.3  CTLE
      4. 7.3.4  Clock and Data Recovery
      5. 7.3.5  Output Driver
      6. 7.3.6  CTLE Boost Setting
      7. 7.3.7  Driver Output Voltage
      8. 7.3.8  Driver Output De-Emphasis
      9. 7.3.9  Driver Output Rise and Fall Time
      10. 7.3.10 Ref_mode 0 Mode (Reference Clock Not Required)
      11. 7.3.11 Ref_mode 3 Mode (Reference Clock Required)
      12. 7.3.12 False Lock Detector Setting
      13. 7.3.13 Reference Clock In
      14. 7.3.14 Reference Clock Out
      15. 7.3.15 Daisy Chain of REFCLK_OUT to REFCLK_IN
      16. 7.3.16 INT
      17. 7.3.17 LOCK_3, LOCK_2, LOCK_1, and LOCK_0
    4. 7.4 Device Functional Modes
      1. 7.4.1 SMBus Master Mode and SMBus Slave Mode
      2. 7.4.2 Address Lines <ADDR_[3:0]>
      3. 7.4.3 SDA and SDC
    5. 7.5 Programming
      1. 7.5.1  SMBus Strap Observation
      2. 7.5.2  Device Revision and Device ID
      3. 7.5.3  Control/Shared Register Reset
      4. 7.5.4  Interrupt Channel Flag Bits
      5. 7.5.5  SMBus Master Mode Control Bits
      6. 7.5.6  Resetting Individual Channels of the Retimer
      7. 7.5.7  Interrupt Status
      8. 7.5.8  Overriding the CTLE Boost Setting
      9. 7.5.9  Overriding the VCO CAP DAC Values
      10. 7.5.10 Overriding the Output Multiplexer
      11. 7.5.11 Overriding the VCO Divider Selection
      12. 7.5.12 Using the PRBS Generator
      13. 7.5.13 Using the Internal Eye Opening Monitor
      14. 7.5.14 Enabling Slow Rise and Fall Time on the Output Driver
      15. 7.5.15 Inverting the Output Polarity
      16. 7.5.16 Overriding the Figure of Merit for Adaptation
      17. 7.5.17 Setting the Rate and Subrate for Lock Acquisition
      18. 7.5.18 Setting the Adaptation/Lock Mode
      19. 7.5.19 Initiating Adaptation
      20. 7.5.20 Setting the Reference Enable Mode
      21. 7.5.21 Overriding the CTLE Settings Used for CTLE Adaptation
      22. 7.5.22 Setting the Output Differential Voltage
      23. 7.5.23 Setting the Output De-emphasis Setting
    6. 7.6 Register Maps
      1. 7.6.1 Register Information
      2. 7.6.2 Bit Fields in the Register Set
      3. 7.6.3 Writing to and Reading from the Control/Shared Registers
      4. 7.6.4 Channel Select Register
      5. 7.6.5 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
  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 CML inputs and outputs have been optimized to work with interconnects using a controlled differential impedance of 100 Ω. It is preferable to route differential lines exclusively on one layer of the board, particularly for the input traces. The use of vias should be avoided if possible. If vias must be used, they 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. See AN-1187 Leadless Leadframe Package (LLP) Application Report (SNOA401) for additional information on QFN (WQFN) packages.

10.2 Layout Example

To minimize the effects of crosstalk, a 5:1 ratio or greater should be maintained between inter-pair spacing.

Figure 10 depicts different transmission line topologies that can be used in various combinations to achieve the optimal system performance. Impedance discontinuities at the differential via can be minimized or eliminated by increasing the swell around each hole and providing for a low inductance return current path. When the via structure is associated with thick backplane PCB, further optimization such as back drilling is often used to reduce the detrimental high frequency effects of stubs on the signal path.

DS100RT410 SNLS399_DF410_example_layout_snls399.gif Figure 10. Different Transmission Line Topologies