SLOS941C May   2016  – January 2018 TPA3128D2 , TPA3129D2

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application Circuit
  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 DC Electrical Characteristics
    6. 6.6 AC Electrical Characteristics
    7. 6.7 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  Gain Setting and Master and Slave
      2. 7.3.2  Input Impedance
      3. 7.3.3  Startup and Shutdown Operation
      4. 7.3.4  PLIMIT Operation
      5. 7.3.5  GVDD Supply
      6. 7.3.6  BSPx AND BSNx Capacitors
      7. 7.3.7  Differential Inputs
      8. 7.3.8  Device Protection System
      9. 7.3.9  DC Detect Protection
      10. 7.3.10 Short-Circuit Protection and Automatic Recovery Feature
      11. 7.3.11 Thermal Protection
      12. 7.3.12 Device Modulation Scheme
        1. 7.3.12.1 BD-Modulation
      13. 7.3.13 Efficiency: LC Filter Required with the Traditional Class-D Modulation Scheme
      14. 7.3.14 Ferrite Bead Filter Considerations
      15. 7.3.15 When to Use an Output Filter for EMI Suppression
      16. 7.3.16 AM Avoidance EMI Reduction
    4. 7.4 Device Functional Modes
      1. 7.4.1 PBTL Mode
      2. 7.4.2 Mono Mode (Single Channel Mode)
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requriements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Select the PWM Frequency
        2. 8.2.2.2 Select the Amplifier Gain and Master/Slave Mode
        3. 8.2.2.3 Select Input Capacitance
        4. 8.2.2.4 Select Decoupling Capacitors
        5. 8.2.2.5 Select Bootstrap Capacitors
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Mode
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.4 PLIMIT Operation

The TPA31xxD2 has a built-in voltage limiter that can be used to limit the output voltage level below the supply rail, the amplifier operates as if it was powered by a lower supply voltage, and thereby limits the output power. Add a resistor divider from GVDD to ground to set the voltage at the PLIMIT pin. An external reference may also be used if tighter tolerance is required. Add a 1-µF capacitor from pin PLIMIT to ground to ensure stability.

TPA3128D2 TPA3129D2 POWER_LIMIT_example_los708.gifFigure 27. Power Limit Example

The PLIMIT circuit sets a limit on the output peak-to-peak voltage. The limiting is done by limiting the duty cycle to a fixed maximum value. The limit can be thought of as a "virtual" voltage rail which is lower than the supply connected to PVCC. The "virtual" rail is approximately four times the voltage at the PLIMIT pin. The output voltage can be used to calculate the maximum output power for a given maximum input voltage and speaker impedance.

Equation 2. TPA3128D2 TPA3129D2 EQ1_Pout_los708.gif

where

  • POUT (10%THD) = 1.25 × POUT (unclipped)
  • RL is the load resistance.
  • RS is the total series resistance including RDS(on), and output filter resistance.
  • VP is the peak amplitude, which is limited by "virtual" voltage rail.

Table 3. Power Limit Example

PVCC (V)PLIMIT VOLTAGE (V)(1)R to GNDR to GVDDOUTPUT VOLTAGE (Vrms)
24 V GVDD Open Short 17.9
24 V 3.3 45 kΩ 51 kΩ 12.67
24 V 2.25 24 kΩ 51 kΩ 9
12 V GVDD Open Short 10.33
12 V 2.25 24 kΩ 51 kΩ 9
12 V 1.5 18 kΩ 68 kΩ 6.3
(1) PLIMIT measurements taken with EVM gain set to 26 dB and input voltage set to 1 Vrms.