SBOS974E August   2019  – October 2024

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    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 VS = 12 V
    6. 5.6 Electrical Characteristics VS = 32 V
    7. 5.7 Timing Requirements
    8. 5.8 Typical Characteristics: VS = 12 V
    9. 5.9 Typical Characteristics: VS = 32 V
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Common-Mode Buffer
      2. 6.3.2 Thermal Protection and Package Power Dissipation
      3. 6.3.3 Output Voltage and Current Drive
      4. 6.3.4 Breakdown Supply Voltage
      5. 6.3.5 Surge Test Results
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Broadband PLC Line Driving
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Curve
    3. 7.3 Best Design Practices
      1. 7.3.1 Do
      2. 7.3.2 Do Not
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
        1. 7.5.1.1 Wafer and Die Information
      2. 7.5.2 Layout Examples
  9. 8 Device and Documentation Support
    1. 8.1 Development Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.2.1.2 Detailed Design Procedure

The closed-loop gain equation for a differential line driver such as the THS6222 is given as AV = 1 + 2 × (RF / RG), where RF = RF1 = RF2. The THS6222 is a current-feedback amplifier and thus the bandwidth of the closed-loop configuration is set by the value of the RF resistor. This advantage of the current-feedback architecture allows for flexibility in setting the differential gain by choosing the value of the RG resistor without reducing the bandwidth as is the case with voltage-feedback amplifiers. The THS6222 is designed to provide excellent bandwidth performance with RF1 = RF2 = 1.24 kΩ. To configure the device in a gain of 10 V/V, the RG resistor is chosen to be 274 Ω. See the TI Precision Labs for more details on how to choose the RF resistor to optimize the performance of a current-feedback amplifier.

Often, a key requirement for PLC applications is the out-of-band suppression specifications. The in-band frequencies carry the encoded data with a certain power level. The line driver must not generate any spurs beyond a certain power level outside the in-band spectrum. In the design requirements of this application example, the minimum out-of-band suppression specification of 35 dB means there must be no frequency spurs in the out-of-band spectrum beyond the –80 dBm/Hz power spectral density, considering the in-band power spectral density is –50 dBm/Hz.

The circuit shown in Figure 7-2 measures the out-of-band suppression specification. The minor difference in components between the circuits of Figure 7-1 and Figure 7-2 does not have any significant impact on the out-of-band suppression results.

THS6222 Measurement Test Circuit for Out-of-Band SuppressionFigure 7-2 Measurement Test Circuit for Out-of-Band Suppression