Tracking, Transfer and Startup Timings Value

The AFE uses the AFE clock to perform conversions. Converting a single analog value to a 12-bit digital data requires tracking clock cycles as defined in the field TRACKTIM, and transfer clock cycles as defined in the field TRANSFER of the AFEC_MR. The tracking phase starts during the conversion of the previous channel.

The AFE conversion time (t_{AFE_conv}) is applicable for all modes and depends on the values of AFEC_MR.TRACKTIM and ADC_MR.TRANSFER. If TRACKTIM > 14, the conversion time is calculated as:

t_{AFE_conv} = (TRANSFER + 6) + (TRACKTIM + 1) x t_{AFE
Clock}

If TRACKTIM ≤ 14, the conversion time is calculated as:

t_{AFE_conv} = ((TRANSFER + 6) +15) x t_{AFE
Clock}

If the tracking time is longer than the conversion time of the12-bit AD converter (t_{AFE_CONV}), the tracking phase is extended to the end of the previous conversion.

The timing diagrams below provide information on the timings of the AFEC:

Figure 1. Sequence of AFE Conversions when Tracking Time > Conversion Time

Figure 2. Sequence of AFE Conversions when Tracking Time < Conversion Time