4.3 ADC Start-Up, Tracking, and Conversion Times

In the ADC Mode register, set the STARTUP field as specified in the SAMA7D6 Series data sheet to allow the ADC internal circuits to settle before starting the first conversion:

• Set ADC_MR.STARTUP = SUT512 (about 25 µs with ADCCLK = 20 MHz, i.e., well above the minimum requirement)

The tracking time is the time required by the ADC to charge its input sampling capacitor to the input voltage. This time, specified in the SAMA7D6 Series data sheet, must be set with the fields TRACKTIM and TRACKX in the ADC Mode register.

• Set ADC_MR.TRACKTIM = 6 and ADC_EMR.TRACKX = 1.

  This results in a tracking time t_TRACK = 24 x t_ADCCLK= 1.2 µs with f_ADCCLK = 20 MHz.

• Assuming a constant input mode control of the ADC (single-ended or differential), the conversion time required by one single V_TEMP or V_BG acquisition is defined as follows:

  t_CONV⁽¹⁾ = t_TRACK + 14 x t_ADCCLK = (24 + 14) x t_ADCCLK = 1.9 µs with f_ADCCLK = 20 MHz