SBAA583 july   2023 PCM1820 , PCM1820-Q1 , PCM1821 , PCM1821-Q1 , PCM1822 , PCM1822-Q1 , PCM3120-Q1 , PCM5120-Q1 , PCM6120-Q1 , TLV320ADC3120 , TLV320ADC5120 , TLV320ADC6120

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 AC Coupled Systems
    2. 1.2 DC Coupled System
  5. 2AC Coupling Schemes
    1. 2.1 Equivalent Circuit
    2. 2.2 Input Pin Waveforms with AC Coupling
    3. 2.3 Selection of Coupling Capacitor
    4. 2.4 Quick Charge Circuit
    5. 2.5 Selection of Capacitor Type
    6. 2.6 Single-Ended and Differential Mode
    7. 2.7 S.N.R in AC Coupled Circuits
  6. 3DC Coupled Scheme
    1. 3.1 Biasing the Pins
    2. 3.2 Electrical Characteristics
    3. 3.3 Application Circuits
      1. 3.3.1 S.N.R in DC Coupled Circuits
  7. 4Application Examples
    1. 4.1  Electret Condenser Microphone: Single Ended DC- Coupled Input
    2. 4.2  Electret Condenser Microphone: Single Ended AC Coupled Input
    3. 4.3  Selection of a Microphone
    4. 4.4  Condenser Microphone: Differential DC-Coupled Input
    5. 4.5  Condenser Microphone: Differential AC-Coupled Input
    6. 4.6  MEMS Microphone: Differential AC Coupled Input
    7. 4.7  Circuit With No Offset and Response Down to DC
    8. 4.8  Improving SNR by Summing the Output of 2 ADC Channels
    9. 4.9  Measure a High Voltage Waveform (+-50 V)
    10. 4.10 I2C Listing
  8. 5Summary
  9. 6References

3.2 Electrical Characteristics

GUID-20230515-SS0I-WQHJ-6K8H-6PVSBHSPDH74-low.svgFigure 3-10 Protection Circuit on Input Pin

The input pins have protection diodes that start conducting when the pin voltage exceeds +0.3 V above AVDD or falls below –0.3 V. The maximum current that can be conducted in these diodes is 10 mA. Soft clipping begins when the voltage at the input pin exceeds 3.6 V. This clipping creates harmonic distortion. When the pin voltage falls below –0.3 V, hard clipping begins.

The voltage level on the analog input pin must stay between VAVDD and VGND for best performance and reliable operation.

Figure 3-11 shows the electrical model of the input pins. The source impedance must be lower than the input impedance.

GUID-20230513-SS0I-MNDR-X6GB-CRP4MLS9CDMT-low.svgFigure 3-11 Equivalent Circuit of Input Pin