SNLS545E March   2017  – July 2022 LMH1297

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Recommended SMBus Interface Timing Specifications
    7. 7.7 Serial Parallel Interface (SPI) Timing Specifications
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  4-Level Input Pins and Thresholds
      2. 8.3.2  Equalizer (EQ) and Cable Driver (CD) Mode Control
        1. 8.3.2.1 EQ/CD_SEL Control
        2. 8.3.2.2 OUT0_SEL and SDI_OUT_SEL Control
      3. 8.3.3  Input Carrier Detect
      4. 8.3.4  –6-dB Splitter Mode Launch Amplitude for SDI_IO+ (EQ Mode Only)
      5. 8.3.5  Continuous Time Linear Equalizer (CTLE)
        1. 8.3.5.1 Line-Side Adaptive Cable Equalizer (SDI_IO+ in EQ mode)
        2. 8.3.5.2 Host-Side Adaptive PCB Trace Equalizer (IN0± in CD Mode)
      6. 8.3.6  Clock and Data (CDR) Recovery
      7. 8.3.7  Internal Eye Opening Monitor (EOM)
      8. 8.3.8  Output Function Control
      9. 8.3.9  Output Driver Control
        1. 8.3.9.1 Line-Side Output Cable Driver (SDI_IO+ in CD mode, SDI_OUT+ in EQ or CD mode)
          1. 8.3.9.1.1 Output Amplitude (VOD)
          2. 8.3.9.1.2 Output Pre-Emphasis
          3. 8.3.9.1.3 Output Slew Rate
          4. 8.3.9.1.4 Output Polarity Inversion
        2. 8.3.9.2 Host-Side 100-Ω Output Driver (OUT0± in EQ or CD mode)
      10. 8.3.10 Status Indicators and Interrupts
        1. 8.3.10.1 LOCK_N (Lock Indicator)
        2. 8.3.10.2 CD_N (Carrier Detect)
        3. 8.3.10.3 INT_N (Interrupt)
      11. 8.3.11 Additional Programmability
        1. 8.3.11.1 Cable EQ Index (CEI)
        2. 8.3.11.2 Digital MUTEREF
    4. 8.4 Device Functional Modes
      1. 8.4.1 System Management Bus (SMBus) Mode
        1. 8.4.1.1 SMBus Read and Write Transaction
          1. 8.4.1.1.1 SMBus Write Operation Format
          2. 8.4.1.1.2 SMBus Read Operation Format
      2. 8.4.2 Serial Peripheral Interface (SPI) Mode
        1. 8.4.2.1 SPI Read and Write Transactions
        2. 8.4.2.2 SPI Write Transaction Format
        3. 8.4.2.3 SPI Read Transaction Format
        4. 8.4.2.4 SPI Daisy Chain
    5. 8.5 Register Maps
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 SMPTE Requirements and Specifications
      2. 9.1.2 Low-Power Optimization in CD Mode
      3. 9.1.3 Optimized Loop Bandwidth Settings for Arria 10 FPGA Applications
    2. 9.2 Typical Applications
      1. 9.2.1 Bidirectional I/O
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Cable Equalizer With Loop-Through
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Board Stack-Up and Ground References
      2. 11.1.2 High-Speed PCB Trace Routing and Coupling
        1. 11.1.2.1 SDI_IO± and SDI_OUT±:
        2. 11.1.2.2 IN0± and OUT0±:
      3. 11.1.3 Anti-Pads
      4. 11.1.4 BNC Connector Layout and Routing
      5. 11.1.5 Power Supply and Ground Connections
      6. 11.1.6 Footprint Recommendations
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.4.1.1 SMBus Read and Write Transaction

SMBus is a two-wire serial interface through which various system component chips can communicate with the controller. Target devices are identified by having a unique device address. The two-wire serial interface consists of SCL and SDA signals. SCL is a clock output from the controller to all of the target devices on the bus. SDA is a bidirectional data signal between the controller and target devices. The LMH1297 SMBus SCL and SDA signals are open-drain and require external pullup resistors.

Start and Stop:

The controller generates Start and Stop patterns at the beginning and end of each transaction.

  • Start: High-to-low transition (falling edge) of SDA while SCL is high.
  • Start: High-to-low transition (falling edge) of SDA while SCL is high.

GUID-84131D60-4A96-4855-BCE3-D1C36CF16D10-low.gifFigure 8-4 Start and Stop Conditions

The controller generates nine clock pulses for each byte transfer. The 9th clock pulse constitutes the ACK cycle. The transmitter releases SDA to allow the receiver to send the ACK signal. An ACK is recorded when the device pulls SDA low, while a NACK is recorded if the line remains high.

GUID-33EF6F99-CB98-45C9-9A0C-59A95474D7CD-low.gifFigure 8-5 Acknowledge (ACK)