SLAA701B October   2016  – June 2026 TAS5342A , TAS5342LA , TAS5352 , TAS5630B , TPA3220 , TPA3221 , TPA3251 , TPA3255 , TPA3255-Q1

 

  1.   1
  2.   Trademarks
  3.   Abstract
  4. 1LC Filter Design
    1. 1.1 Class-D Output Configurations
      1. 1.1.1 Bridged-Tied Load (BTL)
      2. 1.1.2 Parallel Bridge-Tied Load (PBTL)
      3. 1.1.3 Single-Ended (SE)
    2. 1.2 Class-D Modulation Schemes
      1. 1.2.1 AD (Traditional) Modulation
      2. 1.2.2 BD Modulation
    3. 1.3 Class-D Output LC Filter
      1. 1.3.1 Output LC Filter Frequency Response Properties
      2. 1.3.2 Class-D BTL Output LC Filter Topologies
      3. 1.3.3 Single-Ended Filter Calculations
      4. 1.3.4 Type-1 Filter Analysis
        1. 1.3.4.1 Type-1 Frequency Response Example
      5. 1.3.5 Type-2 Filter Analysis
        1. 1.3.5.1 Type-2 Frequency Response Example
      6. 1.3.6 Hybrid Filter for AD Modulation
        1. 1.3.6.1 Hybrid Filter Frequency Response Example
      7. 1.3.7 AD Modulation With Type-1 or Type-2 Filters
      8. 1.3.8 LC Filter Quick Selection Guide
    4. 1.4 Inductor Selection for High-Performance Class-D Audio
      1. 1.4.1 Inductor Linearity
      2. 1.4.2 Ripple Current
        1. 1.4.2.1 Calculating Ripple Current for a Single-Supply Class-D Amplifier
      3. 1.4.3 Minimum Inductance
      4. 1.4.4 Core Loss
      5. 1.4.5 DC Resistance (DCR)
      6. 1.4.6 Inductor Study With the TPA3251 Device
        1. 1.4.6.1 Results
        2. 1.4.6.2 Conclusion
    5. 1.5 Capacitor Considerations
      1. 1.5.1 Class-D Output Voltage Overview
        1. 1.5.1.1 Ripple Voltage
        2. 1.5.1.2 37
      2. 1.5.2 Capacitor Ratings and Specifications
        1. 1.5.2.1 Maximum Voltage or Rated DC Voltage
        2. 1.5.2.2 ESR and Dissipation Factor
        3. 1.5.2.3 Maximum Temperature Rise (Rated AC Voltage and AC Current)
        4. 1.5.2.4 Pulse Rise Time (dv/dt) or Peak Current (Ipeak)
      3. 1.5.3 Capacitor Types
        1. 1.5.3.1 Selecting a Capacitor Type
        2. 1.5.3.2 Metalized Film Capacitors
          1. 1.5.3.2.1 AC Voltage or Current Rating
          2. 1.5.3.2.2 Temperature Coefficient
        3. 1.5.3.3 Ceramic Capacitors
          1. 1.5.3.3.1 Size
          2. 1.5.3.3.2 DC Bias Voltage
          3. 1.5.3.3.3 Temperature Coefficient
          4. 1.5.3.3.4 Reliability
    6. 1.6 Related Collateral
  5. 2Reference
  6. 3Reference
  7. 4Revision History

1.3.7 AD Modulation With Type-1 or Type-2 Filters

Since the Cg capacitors on the Type-2 filter share a common node through ground, differential signals will see a capacitance value of Cg / 2 since the capacitors appear in series for differential signals only. Therefore, with proper selection of the Cg capacitance value, the Type-2 can also be used for AD modulation class-D amplifiers which require a differential filter. Conversion from Type-1 to Type-2 only requires scaling of CBTL by a factor of 2. That is, Cg = 2 x CBTL for identical filter cut-off frequency and damping factor.

Type-1 AD Modulation Filter Converted to Type-2Figure 1-19 Type-1 AD Modulation Filter Converted to Type-2