SLOS810A October   2019  – August 2020 TPA3139D2

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  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
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics,
      1. 6.7.1 Bridge -Tied Load (BTL)
      2. 6.7.2 Paralleled Bridge -Tied Load (PBTL)
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Analog Gain
      2. 7.3.2  SD/ FAULT and MUTE Operation
      3. 7.3.3  PLIMIT
      4. 7.3.4  Spread Spectrum and De-Phase Control
      5. 7.3.5  GVDD Supply
      6. 7.3.6  DC Detect
      7. 7.3.7  PBTL Select
      8. 7.3.8  Short-Circuit Protection and Automatic Recovery Feature
      9. 7.3.9  Over-Temperature Protection (OTP)
      10. 7.3.10 Over-Voltage Protection (OVP)
      11. 7.3.11 Under-Voltage Protection (UVP)
    4. 7.4 Device Functional Modes
      1. 7.4.1 MODE_SEL = LOW: BD Modulation
      2. 7.4.2 MODE_SEL = HIGH: Low-Idle-Current 1SPW Modulation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 PCB Material Recommendation
        2. 8.2.1.2 PVCC Capacitor Recommendation
        3. 8.2.1.3 Decoupling Capacitor Recommendations
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Ferrite Bead Filter Considerations
        2. 8.2.2.2 Efficiency: LC Filter Required with the Traditional Class-D Modulation Scheme
        3. 8.2.2.3 When to Use an Output Filter for EMI Suppression
        4. 8.2.2.4 Input Resistance
        5. 8.2.2.5 Input Capacitor, Ci
        6. 8.2.2.6 BSN and BSP Capacitors
        7. 8.2.2.7 Differential Inputs
        8. 8.2.2.8 Using Low-ESR Capacitors
      3. 8.2.3 Application Performance Curves
        1. 8.2.3.1 EN55013 Radiated Emissions Results
        2. 8.2.3.2 EN55022 Conducted Emissions Results
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Decoupling, CS
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary

Package Options

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

8.2.2.2 Efficiency: LC Filter Required with the Traditional Class-D Modulation Scheme

The main reason that the traditional class-D amplifier requires an output filter is that the switching waveform results in maximum current flow. This causes more loss in the load, which causes lower efficiency. The ripple current is large for the traditional modulation scheme, because the ripple current is proportional to voltage multiplied by the time at that voltage. The differential voltage swing is 2 × VCC, and the time at each voltage is half the period for the traditional modulation scheme. An ideal LC filter is required to store the ripple current from each half cycle for the next half cycle, while any resistance causes power dissipation. The speaker is both resistive and reactive, whereas an LC filter is almost purely reactive.

The TPA3139D2 modulation scheme has little loss in the load without a filter because the pulses are short and the change in voltage is VCC instead of 2 × VCC. As the output power increases, the pulses widen, making the ripple current larger. Ripple current could be filtered with an LC filter for increased efficiency, but for most applications the filter is not required.

An LC filter with a cutoff frequency less than the class-D switching frequency allows the switching current to flow through the filter instead of the load. The filter has less resistance but higher impedance at the switching frequency than the speaker, which results in less power dissipation, therefore increasing efficiency.