SLAAED0 March   2024 TAS2764 , TAS2780 , TAS2781

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Measurement Methodology
  6. 3 Introduction to Noise-gate and Pop in Class-D Amplifiers
  7. 4 Causes of Pop in TAS27xx family of Class-D Amplifiers
  8. 5 Click and Pop Using TAS27xx
  9. 6 Click and Pop Measurement Technique Using AP v6.0. 2
    1. 6.1  Measurement Setup
    2. 6.2  Filter Settings
    3. 6.3  Data Capture Settings
    4. 6.4  Auto Range Settings for Pop Measurement
    5. 6.5  ASI or I2S Configurations for Pop Measurement
    6. 6.6  APx Sound Level Meter Utility
    7. 6.7  Data Acquisition
    8. 6.8  Interpreting Click and Pop Waveforms
    9. 6.9  Post Processing of AP Waveforms
    10. 6.10 A-Weighted Click and Pop Numbers
    11. 6.11 Exporting the A-Weighted Numbers
  10. 7 Noise-Gate Pop and Measurement Technique Using APx
  11. 8 Configuring TAS2764 for Improved Click and Pop Noise Performance
    1. 8.1 Explanation
  12. 9 Summary
  13. 10References

5 Click and Pop Using TAS27xx

A method to minimize click and pop noise is to prevent an abrupt build-up of the differential error voltage across the speaker. This is done by soft-stepping of the differential Class-D output voltage. This is similar to the concept of volume ramping the audio signal.

One key technique used by TI to minimize pop is using the Y-bridge feature in TAS27xx family of devices. In the Y-bridge mode of operation, the Class-D amplifier power stage switches on VBAT supply rather than PVDD for lower audio inputs. This is done to reduce switching losses in the power stage and improve the device efficiency at lower power. This feature also significantly helps reduce pop. During power-up, for example, the Class-D always switches out of VBAT supply and switches into PVDD later in the power sequence. This helps minimize the differential error built up across the speaker. Similarly, before shutdown the Class-D enters VBAT switching to reduce pop.

TI also uses several patented soft-stepping techniques to build-up the Class-D output PWM pulses to make sure smooth build-up of differential voltage across the speaker. Table 5-1 summarizes the click and pop performance in TI’s TAS27xx family of devices.

Table 5-1 Click and Pop Performance in TAS27xx
Device Click and Pop (Typical) Condition (Measured as per Data Sheet)
TAS2764 1mV TA = 25 °C, PVDD = 12V, VBAT1S = 3.8V, AVDD = 1.8V IOVDD =1.2V, RL = 4Ω + 16µH fs = 48kHz, Gain = 21dBV, SDZ = 1, EDGE_RATE[1:0]=00, NG_EN=0, EN_LLSR=1, PWR_MODE1, Measured filter free as in Section 7 (unless otherwise noted).
TAS2780 0.8mV TA = 25 °C, PVDD = 18V, VBAT1S = 3.8V, AVDD = 1.8V, IOVDD =1.8V, RL = 4Ω + 15µH, fs = 48kHz, Gain = 21dBV, SDZ = 1, NG_EN=0, EN_LLSR=0, PWR_MODE1(2), measured filter free as in Section 7 (unless otherwise noted).
TAS2781 0.8mV TA = 25 °C, PVDD = 18V, VBAT1S = 3.8V, AVDD = 1.8V, IOVDD =1.8V, RL = 4Ω + 15µH, fs = 48kHz, Gain = 21dBV, SDZ = 1, NG_EN=0, EN_LLSR=0, PWR_MODE1(2), measured filter free as in Section 7 (unless otherwise noted).