SNLS231P September   2006  – August 2024 DS90UR124-Q1 , DS90UR241-Q1

PRODUCTION DATA  

  1.   1
  2. 1Features
  3. 2Applications
  4. 3Description
  5. 4Pin Configuration and Functions
  6. 5Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Serializer Input Timing Requirements for TCLK
    7. 5.7 Serializer Switching Characteristics
    8. 5.8 Deserializer Switching Characteristics
    9. 5.9 Typical Characteristics
  7. 6Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Initialization and Locking Mechanism
      2. 6.3.2  Data Transfer
      3. 6.3.3  Resynchronization
      4. 6.3.4  Powerdown
      5. 6.3.5  Tri-State
      6. 6.3.6  Pre-Emphasis
      7. 6.3.7  AC-Coupling and Termination
        1. 6.3.7.1 Receiver Termination Option 1
        2. 6.3.7.2 Receiver Termination Option 2
        3. 6.3.7.3 Receiver Termination Option 3
      8. 6.3.8  Signal Quality Enhancers
      9. 6.3.9  @SPEED-BIST Test Feature
      10. 6.3.10 Backward-Compatible Mode With DS90C241 and DS90C124
    4. 6.4 Device Functional Modes
  8.   Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Using the DS90UR241 and DS90UR124
      2. 7.1.2 Display Application
      3. 7.1.3 Typical Application Connection
    2. 7.2 Typical Applications
      1. 7.2.1 DS90UR241-Q1 Typical Application Connection
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Power Considerations
          2. 7.2.1.2.2 Noise Margin
          3. 7.2.1.2.3 Transmission Media
          4. 7.2.1.2.4 46
          5. 7.2.1.2.5 Live Link Insertion
        3. 7.2.1.3 Application Curves
      2. 7.2.2 DS90UR124 Typical Application Connection
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 PCB Layout and Power System Considerations
        2. 7.4.1.2 LVDS Interconnect Guidelines
      2. 7.4.2 Layout Examples
  9. 7Device and Documentation Support
    1. 7.1 Device Support
    2. 7.2 Documentation Support
      1. 7.2.1 Related Documentation
    3. 7.3 Receiving Notification of Documentation Updates
    4. 7.4 Support Resources
    5. 7.5 Trademarks
    6. 7.6 Electrostatic Discharge Caution
    7. 7.7 Glossary
  10. 8Revision History
  11.   Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.6 Pre-Emphasis

The DS90UR241 features a Pre-Emphasis function used to compensate for long or lossy transmission media. Cable drive is enhanced with a user selectable Pre-Emphasis feature that provides additional output current during transitions to counteract cable loading effects. The transmission distance is limited by the loss characteristics and quality of the media. Pre-Emphasis adds extra current during LVDS logic transition to reduce the cable loading effects and increase driving distance. In addition, Pre-Emphasis helps provide faster transitions, increased eye openings, and improved signal integrity. The ability of the DS90UR241 to use the Pre-Emphasis feature extends the transmission distance up to 10 meters in most cases.

To enable the Pre-Emphasis function, the “PRE” pin requires one external resistor (Rpre) to Vss to set the additional current level. Values of Rpre must be between 6kΩ and 100MΩ. Values less than 6kΩ must not be used. A lower input resistor value on the ”PRE” pin increases the magnitude of dynamic current during data transition. The additional source current is based on the following formula: PRE = (RPRE ≥ 6kΩ); IMAX = [48 / RPRE]. For example if Rpre = 15kΩ , then the Pre-Emphasis current is increase by an additional 3.2mA.

The amount of Pre-Emphasis for a given media depends on the transmission distance of the application. In general, too much Pre-Emphasis can cause over or undershoot at the receiver input pins. This can result in excessive noise, crosstalk and increased power dissipation. For short cables or distances, Pre-Emphasis may not be required. Signal quality measurements are recommended to determine the proper amount of Pre-Emphasis for each application.