38.5.1 Analog-to-Digital Conversion

Once the programmed start-up time (ADC_MR.STARTUP) has elapsed, ADC conversions are sequenced by three operating times:

  • Tracking time—the time for the ADC to charge its input sampling capacitor to the input voltage. When several channels are converted consecutively, the inherent tracking time is 6 ADC clock cycles. However, the tracking time can be increased using ADC_MR.TRACKTIM and the TRACKX field in the Extended Mode register (ADC_EMR).
  • ADC inherent conversion time—the time for the ADC to convert the sampled analog voltage. This time is constant and is defined from start of conversion to end of conversion.
  • Channel conversion period—the effective time between the end of the current channel conversion and the end of the next channel conversion.
    Figure 38-2. Sequence of Consecutive ADC Conversions with TRACKTIM = 0
    Figure 38-3. Sequence of Consecutive ADC Conversions with TRACKTIM = 4 and TRACKX = 1