5.2.5.4 ADC Input Sampling Capacitor Charging Time (Tracking Time)

The ADC embeds an input capacitor to sample the analog input. This capacitor must be fully charged to provide a correct conversion result.

The analog sensor connected to the ADC has a serial impedance (also known as “output impedance” or “source impedance”). The tracking time must ensure the error introduced by the charge is lower than the quantification error introduced by the ADC resolution.

It is recommended to use a value higher or equal to 10 x Rs x C for the tracking time (refer to the Electrical Characteristics section for value of C).

The ADC has an inherent tracking time, and additional time can be configured (see ADC_MR).

The full voltage range of the ADC (i.e., ADVREFP-GNDIN33) must be used to calculate the required tracking time, especially when multiple channels are enabled for conversion. In such case, one channel can be tied to GNDIN33 and the consecutive channel in the conversion sequence can be tied to ADVREFP.