SPVA062 June   2026 PCM4220 , PCM4222 , TLV320ADC6120 , TLV320ADC6140

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Detailed Description
    1. 2.1 Why Idle Tones?
    2. 2.2 How To Improve Idle Channel Spectrum in Audio Band
      1. 2.2.1 Example 1 – TLV320ADC6120
      2. 2.2.2 Example 2 – PCM4222
  6. 3Summary
  7. 4References

2.2.2 Example 2 – PCM4222

Figure 2-4 shows the typical connections to operate the PCM4222 in PCM or DSD mode.


Typical Connections for PCM and DSD Output Modes

Figure 2-7 Typical Connections for PCM and DSD Output Modes

Figure 2-8 shows the FFT spectrum for idle input with 0mV and 5mV offset voltages.

FFT Spectrum for 0mV and 5mV OffsetFigure 2-8 FFT Spectrum for 0mV and 5mV Offset

Another solution to address the spurious idle channel tones on PCM4222 is to change the operating VCC1 and VCC2 supply voltages' value from 4V to 4.35V. The FFT with improved spectral performance is shown in Figure 2-9.

FFT Spectrum for 4V and 4.35V VCCFigure 2-9 FFT Spectrum for 4V and 4.35V VCC

The user should note, however, that operating the device at this supply value impacts ADC's performance. For the device under test in this example, the THD+N changed from -108dB (at 4V) to -104dB (at 4.35V).