SNLS534D April   2016  – June 2018 LMH1226

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Block Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Recommended SMBus Interface AC Timing Specifications
    7. 6.7 Serial Parallel Interface (SPI) AC Timing Specifications
    8. 6.8 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 4-Level Input Configuration Pins
      2. 7.3.2 Input Carrier Detect
      3. 7.3.3 Continuous Time Linear Equalizer (CTLE)
        1. 7.3.3.1 Adaptive PCB Trace Equalizer (IN1±)
      4. 7.3.4 Input-Output Mux Selection
      5. 7.3.5 Clock and Data Recovery (CDR) Reclocker
      6. 7.3.6 Internal Eye Opening Monitor (EOM)
      7. 7.3.7 Output Function Control
      8. 7.3.8 Output Driver Amplitude and De-Emphasis Control
      9. 7.3.9 Status Indicators and Interrupts
        1. 7.3.9.1 LOCK_N (Lock Indicator)
        2. 7.3.9.2 CD_N (Carrier Detect)
        3. 7.3.9.3 INT_N (Interrupt)
    4. 7.4 Device Functional Modes
      1. 7.4.1 System Management Bus (SMBus) Mode
        1. 7.4.1.1 SMBus Read and Write Transactions
          1. 7.4.1.1.1 SMBus Write Operation Format
          2. 7.4.1.1.2 SMBus Read Operation Format
      2. 7.4.2 Serial Peripheral Interface (SPI) Mode
        1. 7.4.2.1 SPI Read and Write Transactions
          1. 7.4.2.1.1 SPI Write Transaction Format
          2. 7.4.2.1.2 SPI Read Transaction Format
        2. 7.4.2.2 SPI Daisy Chain
    5. 7.5 LMH1226 Register Map
      1. 7.5.1 Share Register Page
      2. 7.5.2 CTLE/CDR Register Page
      3. 7.5.3 Drivers Register Page
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 General Guidance for SMPTE and 10 GbE Applications
      2. 8.1.2 LMH1219 and LMH1226 Compatibility
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Recommended VOD and DEM Register Settings
      4. 8.2.4 Application Performance Plots
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 PCB Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    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

10.1 PCB Layout Guidelines

The following guidelines are recommended for designing the board layout for the LMH1226:

  1. Choose a suitable board stack-up that supports 100-Ω differential trace routing on the board's top layer. This is typically done with a Layer 2 ground plane reference for the 100-Ω differential traces.
  2. Place anti-pad (ground relief) on the power and ground planes directly under the 4.7-µF AC coupling capacitor and IC landing pads to minimize parasitic capacitance. The size of the anti-pad depends on the board stack-up and can be determined by a 3-dimension electromagnetic simulation tool.
  3. Keep trace length within 1-2 inches between the SFP module and IN1±. This minimizes insertion loss and return loss.
  4. Use coupled differential traces with 100-Ω impedance for signal routing to IN1±, OUT0± and OUT1±. They are usually 5-8 mil trace width reference to a ground plane at Layer 2.
  5. The exposed pad EP of the package should be connected to the ground plane through an array of vias. These vias are solder-masked to avoid solder flowing into the plated-through holes during the board manufacturing process.
  6. Connect each supply pin (VDD_CDR, VIN, VDDIO, VDD_LDO) to the power or ground planes with a short via. The via is usually placed tangent to the supply pins' landing pads with the shortest trace possible.
  7. Power supply bypass capacitors should be placed close to the supply pins. They are commonly placed at the bottom layer and share the ground of the EP.