SWRA679 January   2021 CC3200 , CC3220R , CC3220S , CC3220SF , CC3230S , CC3230SF , CC3235S , CC3235SF

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Basics of the SAR ADC Architecture
    2. 1.2 Introduction to the CC32XX ADC
      1. 1.2.1 Main Features
      2. 1.2.2 ADC Sampling Operation
      3. 1.2.3 ADC Additional Information
  3. 2ADC Application Examples
    1. 2.1 Battery Voltage Measurements
      1. 2.1.1 Important Considerations
        1. 2.1.1.1 Extra Current Draw
        2. 2.1.1.2 Droop Correction
        3. 2.1.1.3 Offset Adjustment
        4. 2.1.1.4 Least Squares Fit
        5. 2.1.1.5 Choosing the Capacitor (for droop correction)
        6. 2.1.1.6 First Measurement
        7. 2.1.1.7 Time Between Measurements
  4. 3AC Measurements
  5. 4Useful References
    1. 4.1 Smart Thermostat
    2. 4.2 Measuring Air Quality With the Winsen MP503 Analog Sensor
    3. 4.3 Touch Position Detection With HMI Through Resistive Touchscreen
  6. 5References

1.2.3 ADC Additional Information

The inputs to the ADC are required to be well within 1.4 V to avoid clipping, which will cause distortion. The ADC inputs can be damaged if an input voltage higher than 1.8 V is applied to these pin. The 1.8 V hard limit must be considered from both the software and hardware points of view. Always add a resistor divider/buffer to bring down the measurement signal voltage to within the ADC limits.

The internal circuit of the ADC alone is stated in the data sheet. However, in addition to the sampling capacitors, there are additional muxes in the path that add their own capacitance. All of this capacitance adds in parallel to create an equivalent capacitance of about 12 pF at the device pin.

For more information on CC32xx ADC characteristics, see the CC3220R, CC3220S, and CC3220SF SimpleLink™ Wi-Fi® Single-Chip Wireless MCU Solutions Data Sheet.