SLAS535F September   2007  – October 2018 DAC5652A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Functional Block Diagram
  3. 3 Description
  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: DC
    6. 6.6  Electrical Characteristics: AC
    7. 6.7  Electrical Characteristics: Digital Input
    8. 6.8  Electrical Characteristics: Power Supply
    9. 6.9  Switching Characteristics
    10. 6.10 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 Digital Inputs
      2. 7.3.2 References
        1. 7.3.2.1 Internal Reference
        2. 7.3.2.2 External Reference
    4. 7.4 Device Functional Modes
      1. 7.4.1 Input Interfaces
        1. 7.4.1.1 Dual-Bus Data Interface and Timing
        2. 7.4.1.2 Single-Bus Interleaved Data Interface and Timing
      2. 7.4.2 Gain Setting Option
      3. 7.4.3 Sleep Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 DAC Transfer Function
        1. 8.1.1.1 Analog Outputs
      2. 8.1.2 Output Configurations
      3. 8.1.3 Differential With Transformer
      4. 8.1.4 Single-Ended Configuration
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.1.3 Differential With Transformer

Using an RF transformer provides a convenient way of converting the differential output signal into a single-ended signal while achieving excellent dynamic performance. The appropriate transformer must be carefully selected based on the output frequency spectrum and impedance requirements.

The differential transformer configuration has the benefit of significantly reducing common-mode signals, thus improving the dynamic performance over a wide range of frequencies. Furthermore, by selecting a suitable impedance ratio (winding ratio) the transformer can provide optimum impedance matching while controlling the compliance voltage for the converter outputs.

Figure 18 and Figure 19 show 50-Ω doubly-terminated transformer configurations with 1:1 and 4:1 impedance ratios, respectively. Note that the center tap of the primary input of the transformer has to be grounded to enable a dc-current flow. Applying a 20-mA full-scale output current would lead to a 0.5-VPP output for a 1:1 transformer and a 1-VPP output for a 4:1 transformer. In general, the 1:1 transformer configuration has a better output distortion, but the 4:1 transformer has 6 dB higher output power.

DAC5652A Drive1-1_las452.gifFigure 18. Driving a Doubly-Terminated 50-Ω Cable Using a 1:1 Impedance Ratio Transformer
DAC5652A Drive4-1_las452.gifFigure 19. Driving a Doubly-Terminated 50-Ω Cable Using a 4:1 Impedance Ratio Transformer